Hadoop HDFS Change Log

Release 2.7.7 - 2018-07-18

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

    HDFS-13602. Add checkOperation(WRITE) checks in FSNamesystem.
    Contributed by Chao Sun.

  OPTIMIZATIONS

  BUG FIXES

    HDFS-13486. Backport HDFS-11817 (A faulty node can cause a lease
    leak and NPE on accessing data) to branch-2.7.
    Contributed by Kihwal Lee.

    HDFS-12156. TestFSImage fails without -Pnative
    Contributed Akira Ajisaka.

Release 2.7.6 - 2018-04-16

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

    HDFS-11003. Expose XmitsInProgress through DataNodeMXBean.
    (Brahma Reddy Battula)

    HDFS-11187. Optimize disk access for last partial chunk checksum of
    Finalized replica. (Gabor Bota, Wei-Chiu Chuang via Xiao Chen)

    HDFS-12884. BlockUnderConstructionFeature.truncateBlock should be of type
    BlockInfo. (chencan via shv)

  OPTIMIZATIONS

  BUG FIXES

    HDFS-12881. Output streams closed with IOUtils suppressing write errors.
    (Ajay Kumar via jlowe)

    HDFS-12347. TestBalancerRPCDelay#testBalancerRPCDelay fails very frequently.
    (Bharat Viswanadham via Tsz-Wo Nicholas Sze)

    HDFS-12371. BlockVerificationFailures and BlocksVerified show up as 0
    in Datanode JMX. (Hanisha Koneru via Kihwal Lee, shv).

    HDFS-13120. Snapshot diff could be corrupted after concat. (xyao)

    HDFS-7959. WebHdfs logging is missing on Datanode (Kihwal Lee via sjlee)
    Backport HDFS-13126 by Erik Krogen.

    HDFS-10453. ReplicationMonitor thread could stuck for long time
    due to the race between replication and delete of same file in a
    large cluster. Contributed by He Xiaoqiao.

    HDFS-13112. Token expiration edits may cause log corruption or deadlock.
    (daryn via kihwal)

    HDFS-4210. Throw helpful exception when DNS entry for JournalNode cannot be
    resolved. (Charles Lamb and John Zhuge)

    HDFS-13195. DataNode conf page cannot display the current value after
    reconfig. (Mao Baolong via kihwal)

    HDFS-12299. Race Between update pipeline and DN Re-Registration.
    (Brahma Reddy Battula. Backport by Wei-Chiu Chuang, Konstantin Shvachko)

Release 2.7.5 - 2017-12-14

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

    HDFS-9153. Pretty-format the output for DFSIO. (Kai Zheng via wheat9)

    HDFS-8797. WebHdfsFileSystem creates too many connections for pread. (jing9)

    HDFS-12131. Add some of the FSNamesystem JMX values as metrics.
    (Erik Krogen via wang, shv)
    
    HDFS-12420. Add an option to disallow 'namenode format -force'.
    (Ajay Kumar via Arpit Agarwal, zhz)
    
    HDFS-10984. Expose nntop output as metrics. (Siddharth Wagle via xyao, zhz)

    HDFS-9259. Make SO_SNDBUF size configurable at DFSClient side for hdfs write
    scenario. (original patch Mingliang Liu via Ming Ma, branch-2.7 backport
    done under HDFS-12823, Erik Krogen via zhz).

    HDFS-12596. Add TestFsck#testFsckCorruptWhenOneReplicaIsCorrupt
    back to branch-2.7. (Xiao Chen)

  OPTIMIZATIONS

    HDFS-10711. Optimize FSPermissionChecker group membership check.
    (Daryn Sharp via kihwal)

    HDFS-12323. NameNode terminates after full GC thinking QJM unresponsive
    if full GC is much longer than timeout. (Erik Krogen via shv)

    HDFS-8829. Make SO_RCVBUF and SO_SNDBUF size configurable for
    DataTransferProtocol sockets and allow configuring auto-tuning (He Tianyi
    via Colin P. McCabe)

  BUG FIXES

    HDFS-12157. Do fsyncDirectory(..) outside of FSDataset lock.
    (Vinayakumar B. via kihwal)

    HDFS-9107. Prevent NN's unrecoverable death spiral after full GC (Daryn
    Sharp via Colin P. McCabe)

    HDFS-10738. Fix
    TestRefreshUserMappings.testRefreshSuperUserGroupsConfiguration
    test failure. (Rakesh R via kihwal)

    HDFS-8865. Improve quota initialization performance. Contributed by Kihwal Lee.

    HDFS-9003. ForkJoin thread pool leaks. (Kihwal Lee via jing9)

    HDFS-12578. TestDeadDatanode#testNonDFSUsedONDeadNodeReReg failing
    in branch-2.7. (Ajay Kumar via Xiao Chen)

    HDFS-12832. INode.getFullPathName may throw ArrayIndexOutOfBoundsException
    lead to NameNode exit. (shv)

    HDFS-12638. Delete copy-on-truncate block along with the original block,
    when deleting a file being truncated. (shv)

Release 2.7.4 - 2017-08-04

  INCOMPATIBLE CHANGES

    HDFS-7933. fsck should also report decommissioning replicas.
    (Xiaoyu Yao via Chris Nauroth).

  NEW FEATURES

    HDFS-9804. Allow long-running Balancer to login with keytab.
    (Xiao Chen via Zhe Zhang)

    HDFS-8131. Implement a space balanced block placement policy (Liu Shaohui
    via kihwal)

  IMPROVEMENTS

    HDFS-8721. Add a metric for number of encryption zones.
    (Rakesh R via Chris Nauroth)

    HDFS-8883. NameNode Metrics : Add FSNameSystem lock Queue Length.
    (Anu Engineer via Xiaoyu Yao)

    HDFS-8818. Changes the global moveExecutor to per datanode executors and
    changes MAX_SIZE_TO_MOVE to be configurable.(Tsz Wo Nicholas Sze)

    HDFS-8200. Refactor FSDirStatAndListingOp. (Haohui Mai)

    HDFS-9621. Consolidate FSDirStatAndListingOp#createFileStatus to let
    its INodesInPath parameter always include the target INode.
    (Jing Zhao)

    HDFS-10656. Optimize conversion of byte arrays back to path string.
    (Daryn Sharp via kihwal)

    HDFS-10674. Optimize creating a full path from an inode.
    (Daryn Sharp via kihwal)

    HDFS-10662. Optimize UTF8 string/byte conversions.
    (Daryn Sharp via kihwal)

    HDFS-10673. Optimize FSPermissionChecker's internal path usage.
    (Daryn Sharp via kihwal)

    HDFS-10744. Internally optimize path component resolution.
    (Daryn Sharp via kihwal)

    HDFS-9145. Tracking methods that hold FSNamesytemLock for too long.
    (Mingliang Liu via Haohui Mai)

    HDFS-10745. Directly resolve paths into INodesInPath.
    (Daryn Sharp via kihwal)

    HDFS-8824. Do not use small blocks for balancing the cluster.  (szetszwo)

    HDFS-10712. TestDataNodeVolumeFailure should pass not null
    BlockReportContext. (Vinitha Gankidi via shv)

    HDFS-11053. Unnecessary superuser check in versionRequest() (kihwal)

    HDFS-11069. Tighten the authorization in datanode RPC. (kihwal)

    HDFS-8709. Clarify automatic sync in FSEditLog#logEdit. (wang)

    HDFS-10872. Add MutableRate metrics for FSNamesystemLock operations.
    (Erik Krogen via zhz)

    HDFS-10966. Enhance Dispatcher logic on deciding when to give up a source
    DataNode (Mark Wagner and zhz via kihwal)

    HDFS-10534. NameNode WebUI should display DataNode usage histogram.
    (Kai Sasaki via zhz)

    HDFS-11333. Print a user friendly error message when plugins are not found.
    (Wei-Chiu Chuang)

    HDFS-11466. Change dfs.namenode.write-lock-reporting-threshold-ms default
    from 1000ms to 5000ms. (wang via zhz)

    HDFS-8873. Allow the directoryScanner to be rate-limited (Daniel Templeton
    via Colin P. McCabe)

    HDFS-11717. Add unit test for HDFS-11709 StandbyCheckpointer should handle
    non-existing legacyOivImageDir gracefully. (Erik Krogen via shv)

    HDFS-9902. Support different values of dfs.datanode.du.reserved per storage
    type. (Brahma Reddy Battula)

    HDFS-11785. Backport HDFS-9902 to branch-2.7: Support different values of
    dfs.datanode.du.reserved per storage type. (Brahma Reddy Battula)

    HDFS-7990. IBR delete ack should not be delayed. (Daryn Sharp.
    Backport HDFS-11838 by Vinitha Gankidi)

    HDFS-9726. Refactor IBR code to a new class. (Tsz-Wo Nicholas Sze
    Backport HDFS-11839 by Vinitha Reddy Gankidi)

    HDFS-10619. Cache path in InodesInPath. (daryn via kihwal, backported by zhz)

    HDFS-11648. Lazy construct the IIP pathname.
    (daryn via kihwal, backported by zhz)

    HDFS-8549. Abort the balancer if an upgrade is in progress. (wang)
    Backport HDFS-11808 by Akira Ajisaka.

    HDFS-7847. Modify NNThroughputBenchmark to be able to operate on a remote
    NameNode (Charles Lamb via Colin P. McCabe)

    HDFS-9421. NNThroughputBenchmark replication test NPE with -namenode option.
    (Mingliang Liu via xyao)

    HDFS-9503. Use generic option -fs for NNThroughputBenchmark instead of
    -namenode. (Mingliang Liu via shv)

    HDFS-11628. Clarify the behavior of HDFS Mover in documentation.
    (Xiaobing Zhou via arp)

    HDFS-10941. Improve BlockManager#processMisReplicatesAsync log.
    (Chen Liang via Xiaoyu Yao)

  OPTIMIZATIONS

    HDFS-10896. Move lock logging logic from FSNamesystem into FSNamesystemLock.
    (Erik Krogen via Zhe Zhang)

    HDFS-11634. Optimize BlockIterator when iterating starts in the middle.
    (shv)

    HDFS-11384. Balancer disperses getBlocks calls to avoid NameNode's rpc queue
    saturation. (shv)

    HDFS-9412. getBlocks occupies FSLock and takes too long to complete.
    Contributed by He Tianyi. Backport HDFS-11855 by Vinitha Reddy Gankidi.

    HDFS-9710. DN can be configured to send block receipt IBRs in batches.
    (Tsz-Wo Nicholas Sze. Backport HDFS-11837 by Vinitha Reddy Gankidi)

    HDFS-8674. Improve performance of postponed block scans. (Daryn Sharp)

    HDFS-11345. Document the configuration key for FSNamesystem lock
    fairness. (Erik Krogen via aajisaka)

  BUG FIXES
   
    HDFS-8307. Spurious DNS Queries from hdfs shell. (Andres Perez via aengineer)

    HDFS-9696. Garbage snapshot records linger forever. (kihwal)

    HDFS-9601. NNThroughputBenchmark.BlockReportStats should handle
    NotReplicatedYetException on adding block. (iwasakims)

    HDFS-10691. FileDistribution fails in hdfs oiv command due to
    ArrayIndexOutOfBoundsException. (Yiqun Lin via aajisaka)

    HDFS-10763. Open files can leak permanently due to inconsistent
    lease update (kihwal)

    HDFS-9745. TestSecureNNWithQJM#testSecureMode sometimes fails with
    timeouts (Xiao Chen via jlowe)

    HDFS-8915. TestFSNamesystem.testFSLockGetWaiterCount fails intermittently.
    (Masatake Iwasaki via kihwal)

    HDFS-10693. metaSave should print blocks, not LightWeightHashSet.
    (Yuanbo Liu via shv)

    HDFS-10694. processReport() should print blockReportId in each log message.
    (Yuanbo Liu via shv)

    HDFS-10336. TestBalancer failing intermittently because of not reseting
    UserGroupInformation completely. (Yiqun Lin via Akira Ajisaka)

    HDFS-9888. Allow reseting KerberosName in unit tests.
    (Xiao Chen via Zhe Zhang).

    HDFS-10747. o.a.h.hdfs.tools.DebugAdmin usage message is misleading.
    (Mingliang Liu)

    HDFS-10270. TestJMXGet:testNameNode() fails.
    (Gergely Novák via kihwal)

    HDFS-8224. Schedule a block for scanning if its metadata file is
    corrupt. (Rushabh S Shah via We-Chiu Chuang)

    HDFS-9467. Fix data race accessing writeLockHeldTimeStamp in FSNamesystem.
    (Mingliang Liu via Jing Zhao).

    HDFS-10798. Make the threshold of reporting FSNamesystem lock contention
    configurable. (Erik Krogen via Zhe Zhang).

    HDFS-10807. Doc about upgrading to a version of HDFS with snapshots may be
    confusing. (Mingliang Liu)

    HDFS-10625. VolumeScanner to report why a block is found bad.
    (Rushabh S Shah and Yiqun Lin via Yongjun Zhang)

    HDFS-10809. getNumEncryptionZones causes NPE in branch-2.7.
    (Vinitha Reddy Gankidi via Zhe Zhang)

    HDFS-10655. Fix path related byte array conversion bugs. (daryn)

    HDFS-10817. Add Logging for Long-held NN Read Locks.
    (Erik Krogen via Zhe Zhang)

    HDFS-9038. DFS reserved space is erroneously counted towards non-DFS used.
    (Brahma Reddy Battula)

    HDFS-10276. HDFS should not expose path info that user has no permission
    to see. (Yuanbo Liu via Yongjun Zhang)

    HDFS-10716. In Balancer, the target task should be removed when its size
     < 0. (Yiqun Lin via Tsz Wo Nicholas Sze)

    HDFS-10843. Update space quota when a UC block is completed rather
    than committed. (Erik Krogen via shv)

    HDFS-10915. Fix time measurement bug in TestDatanodeRestart.
    (Xiaobing Zhou via Mingliang Liu)

    HDFS-10713. Throttle FsNameSystem lock warnings.
    (Hanisha Koneru via arp)

    HDFS-9885. Correct the distcp counters name while displaying counters.
    (Contributed by Surendra Singh Lilhore via Brahma Reddy Battula)

    HDFS-10889. Remove outdated Fault Injection Framework documentaion.
    (Brahma Reddy Battula)

    HDFS-10878. TestDFSClientRetries#testIdempotentAllocateBlockAndClose
    throws ConcurrentModificationException. (Rushabh S Shaah via kihwal)

    HDFS-10609. Uncaught InvalidEncryptionKeyException during pipeline
    recovery may abort downstream applications.
    (Wei-Chiu Chuang)

    HDFS-10991. Export hdfsTruncateFile symbol in libhdfs.
    (Surendra Singh Lilhore via wang)

    HDFS-11002. Fix broken attr/getfattr/setfattr links in
    ExtendedAttributes.md. (Mingliang Liu via aajisaka)

    HDFS-10512. VolumeScanner may terminate due to NPE in 
    DataNode.reportBadBlocks. Contributed by Wei-Chiu Chuang and Yiqun Lin.

    HDFS-10879. TestEncryptionZonesWithKMS#testReadWrite fails intermittently.
    (xiaochen)

    HDFS-9333. Some tests using MiniDFSCluster errored complaining port in
    use. (iwasakims)

    HDFS-10301. Remove FBR tracking state to fix false zombie storage
    detection for interleaving block reports. (Vinitha Gankidi via shv)

    HDFS-9444. Add utility to find set of available ephemeral ports to
    ServerSocketUtil. (Masatake Iwasaki via Brahma Reddy Battula)

    HDFS-10627. Volume Scanner marks a block as "suspect" even if
    the exception is network-related. (Rushabh S Shah via kihwal)

    HDFS-11015. Enforce timeout in balancer. (kihwal via zhz)

    HDFS-9500. Fix software version counts for DataNodes during rolling upgrade.
    (Erik Krogen via shv)

    HDFS-11087. NamenodeFsck should check if the output writer is still
    writable. (Erik Krogen via shv)

    HDFS-11056. Concurrent append and read operations lead to checksum error.
    (Wei-Chiu Chuang)

    HDFS-11174. Wrong HttpFS test command in doc. (John Zhuge via aajisaka)

    HDFS-11180. Intermittent deadlock in NameNode when failover happens.
    (aajisaka)

    HDFS-11229. HDFS-11056 failed to close meta file. (Wei-Chiu Chuang)

    HDFS-11160. VolumeScanner reports write-in-progress replicas as corrupt
    incorrectly. Contributed by Wei-Chiu Chuang and Yongjun Zhang.

    HDFS-11263. ClassCastException when we use Bzipcodec for Fsimage
    compression. (Brahma Reddy Battula)

    HDFS-11290. TestFSNameSystemMBean should wait until JMX cache is cleared.
    (Eric Krogen via aajisaka)

    HDFS-11352. Potential deadlock in NN when failing over.
    (Erik Krogen via aajisaka)

    HDFS-11379. DFSInputStream may infinite loop requesting block locations. Contributed by Daryn Sharp.

    HDFS-11499. Decommissioning stuck because of failing recovery.
    Contributed by Lukas Majercak and Manoj Govindassamy.

    HDFS-11486. Client close() should not fail fast if the last block is being
    decommissioned. Contributed by Wei-Chiu Chuang and Yiqun Lin.

    HDFS-11615. FSNamesystemLock metrics can be inaccurate due to millisecond precision.
    (Erik Krogen via zhz)

    HDFS-10455. Logging the username when deny the setOwner operation.
    (Tianyi Xu and Rakesh R via Brahma Reddy Battula)

    HDFS-11709. StandbyCheckpointer should handle an non-existing legacyOivImageDir
    gracefully. (Erik Krogen via zhz)

    HDFS-11609. Some blocks can be permanently lost if nodes are decommissioned
    while dead. (kihwal)

    HDFS-11714. Newly added NN storage directory won't get initialized
    and cause space exhaustion. (kihwal)

    HDFS-11766. Fix findbugs warning in branch-2.7. (Chen Liang via aajisaka)

    HDFS-11373. Backport HDFS-11258 and HDFS-11272
    (File mtime change could not save to editlog).
    (Contributed by Jimmy Xiang, backported by Akira Ajisaka)

    HDFS-11795. Fix ASF License warnings in branch-2.7.
    (Yiqun Lin via aajisaka)

    HDFS-11674. reserveSpaceForReplicas is not released if append request failed
    due to mirror down and replica recovered (vinayakumarb)

    HDFS-10987. Make Decommission less expensive when lot of blocks present. 
    (Brahma Reddy Battula)
    
    HDFS-8312. Trash does not descent into child directories to check for permissions. 
   (Contributed By Weiwei Yang via Eric Yang)
    HDFS-11784. Backport HDFS-8312 contributed by Brahma Reddy Battula.

    HDFS-8498. Blocks can be committed with wrong size. (Jing Zhao)
    Backport HDFS-11732 by Zhe Zhang.

    HDFS-10715. NPE when applying AvailableSpaceBlockPlacementPolicy.
    (Guangbin Zhu)

    HDFS-11849. JournalNode startup failure exception should be logged in log file.
    (Contributed By Surendra Singh Lilhore via Brahma Reddy Battula)

    HDFS-11864. Document Metrics to track usage of memory for writes.
    (Contributed by Yiqun Lin via Brahma Reddy Battula)

    HDFS-11377. Balancer hung due to no available mover threads. (yunjiong zhao)

    HDFS-6291. FSImage may be left unclosed in BootstrapStandby#doRun()
    (Sanghyun Yun via vinayakumarb)

    HADOOP-13026 Should not wrap IOExceptions into a AuthenticationException in
    KerberosAuthenticator. Xuan Gong via stevel
    
    HDFS-11445. FSCK shows overall health stauts as corrupt even one replica is corrupt. 
    (Brahma Reddy Battula)

    HDFS-11078. Fix NPE in LazyPersistFileScrubber. (Inigo Goiri via shv)

    HDFS-11893. Fix TestDFSShell.testMoveWithTargetPortEmpty failure.
    (Contributed by Brahma Reddy Battula)

    HDFS-5042. Completed files lost after power failure. (vinayakumarb via kihwal)

    HDFS-11856. Ability to re-add upgrading nodes to pipeline for future
    pipeline updates. (vinayakumarb via kihwal)

    HDFS-11708. Positional read will fail if replicas moved to different DNs
    after stream is opened. (vinayakumarb)

    HDFS-11743. Revert the incompatible fsck reporting output in HDFS-7933
    from branch-2.7. (zhz)

    HDFS-11736. OIV tests should not write outside 'target' directory.
    (Yiqun Lin via aajisaka)

    HDFS-11583. Parent spans are not initialized to NullScope for every
    DFSPacket. (Masatake Iwasaki via aajisaka)

    HDFS-11741. Long running balancer may fail due to expired DataEncryptionKey.
        Contributed by Wei-Chiu Chuang and Xiao Chen.

    HDFS-10733. NameNode terminated after full GC thinking QJM is unresponsive.
    (Vinitha Gankidi via shv)

    HDFS-11280. Allow WebHDFS to reuse HTTP connections to NN.
    (Zheng Shao via wheat9)

    HDFS-10921. TestDiskspaceQuotaUpdate doesn't wait for NN to get out of
    safe mode. (Eric Badger via Mingliang Liu)

    HDFS-11472. Fix inconsistent replica size after a data pipeline failure.
    (Erik Krogen and Wei-Chiu Chuang via shv)

    HDFS-12177. NameNode exits due to setting BlockPlacementPolicy loglevel to Debug.
    (Jiandan Yang via Brahma Reddy Battula)

    HDFS-11742. Improve balancer usability after HDFS-8818. (kihwal)

    HDFS-11896. Non-dfsUsed will be doubled on dead node re-registration.
    (Brahma Reddy Battula via shv)

Release 2.7.3 - 2016-08-25

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

    HDFS-8647. Abstract BlockManager's rack policy into BlockPlacementPolicy.
    (Brahma Reddy Battula via mingma)

    HDFS-7163. WebHdfsFileSystem should retry reads according to the configured
    retry policy. (Eric Payne via kihwal)

    HDFS-9047. Retire libwebhdfs (kihwal)

    HDFS-9569. Log the name of the fsimage being loaded for better
    supportability. (Yongjun Zhang)

    HDFS-9415. Document dfs.cluster.administrators and
    dfs.permissions.superusergroup. (Xiaobing Zhou via Arpit Agarwal)

    HDFS-9634. webhdfs client side exceptions don't provide enough details
    (Eric Payne via kihwal)

    HDFS-9654. Code refactoring for HDFS-8578.  (szetszwo)

    HDFS-9669. TcpPeerServer should respect ipc.server.listen.queue.size
    (Elliot Clark via cmccabe)

    HDFS-4946. Allow preferLocalNode in BlockPlacementPolicyDefault to be
    configurable (James Kinley and Nathan Roberts via kihwal)

    HDFS-8578. On upgrade, Datanode should process all storage/data dirs in
    parallel.  (vinayakumarb and szetszwo via szetszwo)

    HDFS-9048. DistCp documentation is out-of-dated
    (Daisuke Kobayashi via iwasakims)

    HDFS-9860. Backport HDFS-9638 to branch-2.7. (Wei-Chiu Chuang via aajisaka)

    HDFS-8101. DFSClient use of non-constant DFSConfigKeys pulls in WebHDFS
    classes at runtime. (Sean Busbey via atm)

    HDFS-8772. Fix TestStandbyIsHot#testDatanodeRestarts which occasionally fails.
    (Walter Su via wang).

    HDFS-9906. Remove spammy log spew when a datanode is restarted.
    (Brahma Reddy Battula via arp)

    HDFS-2580. NameNode#main(...) can make use of GenericOptionsParser. (harsh)

    HDFS-10264. Logging improvements in FSImageFormatProtobuf.Saver.
    (Xiaobing Zhou via arp)

    HDFS-10186. DirectoryScanner: Improve logs by adding full path of both
    actual and expected block directories. (Rakesh R via szetszwo)

    HDFS-10488. Updated WebHDFS documentation regarding CREATE and MKDIR default
    permissions. (Wellington Chevreuil via wang)

    HDFS-5802. NameNode does not check for inode type before traversing down a
    path. (Xiao Chen via Yongjun Zhang)

    HDFS-9019. Adding informative message to sticky bit permission denied
    exception. (xyao)

    HDFS-8709. Clarify automatic sync in FSEditLog#logEdit. (wang)

  OPTIMIZATIONS

    HDFS-8845. DiskChecker should not traverse the entire tree (Chang Li via
    Colin P. McCabe)

  BUG FIXES

    HDFS-9289. Make DataStreamer#block thread safe and verify genStamp in
    commitBlock. (Chang Li via kihwal)

    HDFS-4937. ReplicationMonitor can infinite-loop in 
    BlockPlacementPolicyDefault#chooseRandom(). (kihwal)

    HDFS-9383. TestByteArrayManager#testByteArrayManager fails.
    (szetszwo via kihwal)

    HDFS-9072. Fix random failures in TestJMXGet (J.Andreina via kihwal)

    HDFS-6481. DatanodeManager#getDatanodeStorageInfos() should check the
    length of storageIDs. (szetszwo via Arpit Agarwal)

    HDFS-9313. Possible NullPointerException in BlockManager if no excess
    replica can be chosen. (mingma)

    HDFS-9314. Improve BlockPlacementPolicyDefault's picking of excess
    replicas. (Xiao Chen via zhz)

    HDFS-9516. Truncate file fails with data dirs on multiple disks.
    (Plamen Jeliazkov via shv)

    HDFS-9533. seen_txid in the shared edits directory is modified during
    bootstrapping (kihwal)

    HDFS-9505. HDFS Architecture documentation needs to be refreshed.
    (Masatake Iwasaki via aajisaka)

    HDFS-8914. Document HA support in the HDFS HdfsDesign.md.
    (Lars Francke via wheat9)

    HDFS-9198. Coalesce IBR processing in the NN. (Daryn Sharp via umamahesh)

    HDFS-9648. TestStartup.testImageChecksum is broken by HDFS-9569's message
    change. (Wei-Chiu Chuang via Yongjun Zhang)

    HDFS-9661. Deadlock in DN.FsDatasetImpl between moveBlockAcrossStorage and
    createRbw (ade via vinayakumarb)

    HDFS-9625. set replication for empty file failed when set storage policy
    (DENG FEI via vinayakumarb)

    HDFS-9690. ClientProtocol.addBlock is not idempotent after HDFS-8071.
    (szetszwo)

    HDFS-9406. FSImage may get corrupted after deleting snapshot.
    (Contributed by Jing Zhao, Stanislav Antic, Vinayakumar B, Yongjun Zhang)

    HDFS-9743. Fix TestLazyPersistFiles#testFallbackToDiskFull (kihwal)

    HDFS-9740. Use a reasonable limit in DFSTestUtil.waitForMetric()
    (Chang Li via vinayakumarb)

    HDFS-9730. Storage ID update does not happen when there is a layout change
    (Tsz Wo Nicholas Sze via kihwal)

    HDFS-9724. Degraded performance in WebHDFS listing as it does not reuse
    ObjectMapper. (Akira AJISAKA via wheat9)

    HDFS-9752. Permanent write failures may happen to slow writers during
    datanode rolling upgrades (Walter Su via kihwal)

    HDFS-9779 . TestReplicationPolicyWithNodeGroup NODE variable picks wrong rack value
    (Kuhu Shukla via umamahesh)

    HDFS-9784. Example usage is not correct in Transparent Encryption document.
    (Takashi Ohnishi via aajisaka)

    HDFS-9765. TestBlockScanner#testVolumeIteratorWithCaching fails
    intermittently. (aajisaka)

    HDFS-9864. Correct reference for RENEWDELEGATIONTOKEN and
    CANCELDELEGATIONTOKEN in webhdfs doc. (Brahma Reddy Battula via aajisaka)

    HDFS-9880. TestDatanodeRegistration fails occasionally (kihwal)

    HDFS-9766. TestDataNodeMetrics#testDataNodeTimeSpend fails intermittently.
    (Xiao Chen via aajisaka)

    HDFS-9851. NameNode throws NPE when setPermission is called on a path that
    does not exist. (Brahma Reddy Battula via aajisaka)

    HDFS-9865. TestBlockReplacement fails intermittently in trunk
    (Lin Yiqun via iwasakims)

    HDFS-9812. Streamer threads leak if failure happens when closing
    DFSOutputStream. (Lin Yiqun via aajisaka)

    HDFS-9904. testCheckpointCancellationDuringUpload occasionally fails.
    (Lin Yiqun via kihwal)

    HDFS-9874. Long living DataXceiver threads cause volume shutdown to block.
    (Rushabh Shah via kihwal)

    HDFS-10178. Permanent write failures can happen if pipeline recoveries
    occur for the first packet (kihwal)

    HDFS-9917. IBR accumulate more objects when SNN was down for sometime.
    (Brahma Reddy Battula via vinayakumarb)

    HDFS-10239. Fsshell mv fails if port usage doesn't match in src and
    destination paths (Kuhu Shukla via kihwal)

    HDFS-9555. LazyPersistFileScrubber should still sleep if there are errors
    in the clear progress (Phil Yang via kihwal)

    HDFS-10245. Fix the findbugs warnings in branch-2.7.
    (Brahma Reddy Battula via aajisaka)

    HDFS-9958. BlockManager#createLocatedBlocks can throw NPE for corruptBlocks
    on failed storages. (Kuhu Shukla via kihwal)

    HDFS-10347. Namenode report bad block method doesn't log the bad block or
    datanode. (Rushabh Shah via kihwal)

    HDFS-2043. TestHFlush failing intermittently. (Lin Yiqun via iwasakims)

    HDFS-10372. Fix for failing TestFsDatasetImpl#testCleanShutdownOfVolume.
    (Rushabh Shah via kihwal)

    HDFS-9476. TestDFSUpgradeFromImage#testUpgradeFromRel1BBWImage
    occasionally fail. (Masatake Iwasaki via aajisaka)

    HDFS-8548. Minicluster throws NPE on shutdown.
    (surendra singh lilhore via xyao)

    HDFS-8581. ContentSummary on / skips further counts on yielding lock
    (J.Andreina via vinayakumarb)

    HDFS-10474. hftp copy fails when file name with Chinese+special char
    in branch-2 (Brahma Reddy Battula)

    HDFS-9530. ReservedSpace is not cleared for abandoned Blocks
    (Brahma Reddy Battula)

    HDFS-10458. getFileEncryptionInfo should return quickly for non-encrypted
    cluster. (zhz)

    HDFS-9365. Balaner does not work with the HDFS-6376 HA setup. (szetszwo)

    HDFS-10335. Mover$Processor#chooseTarget() always chooses the first
    matching target storage group. (Mingliang Liu via szetszwo)

    HDFS-10319. Balancer should not try to pair storages with different types.
    (szetszwo)

    HDFS-10275. TestDataNodeMetrics failing intermittently due to
    TotalWriteTime counted incorrectly. (Yiqun Lin via waltersu4549)

    HDFS-9772. TestBlockReplacement#testThrottler doesn't work as expected.
    (Yiqun Lin via waltersu4549)

    HDFS-10261. TestBookKeeperHACheckpoints doesn't handle ephemeral HTTP
    ports. (Eric Badger via kihwal)

    HDFS-9478. Reason for failing ipc.FairCallQueue contruction should be
    thrown. (Ajith S via arp)

    HDFS-10182. Hedged read might overwrite user's buf.
    (zhouyingchao via waltersu4549)

    HDFS-10623. Remove unused import of httpclient.HttpConnection from
    TestWebHdfsTokens. (Hanish Koneru via Arpit Agarwal)

Release 2.7.2 - 2016-01-25

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

    HDFS-8659. Block scanner INFO message is spamming logs. (Yongjun Zhang)

    HDFS-8099. Change "DFSInputStream has been closed already" message to
    debug log level (Charles Lamb via Colin P. McCabe)

    HDFS-9221. HdfsServerConstants#ReplicaState#getState should avoid calling
    values() since it creates a temporary array. (Staffan Friberg via yliu)

    HDFS-9574. Reduce client failures during datanode restart (kihwal)

  OPTIMIZATIONS

    HDFS-8722. Optimize datanode writes for small writes and flushes (kihwal)

    HDFS-7645. Rolling upgrade is restoring blocks from trash multiple times.
    (Vinayakumar B and Keisuke Ogiwara via Arpit Agarwal)

  BUG FIXES

    HDFS-6945. BlockManager should remove a block from excessReplicateMap and
    decrement ExcessBlocks metric when the block is removed. (aajisaka)

    HDFS-7725. Incorrect "nodes in service" metrics caused all writes to fail.
    (Ming Ma via wang)

    HDFS-8806. Inconsistent metrics: number of missing blocks with replication
    factor 1 not properly cleared. (Zhe Zhang via aajisaka)

    HDFS-8656. Preserve compatibility of ClientProtocol#rollingUpgrade after
    finalization. (wang)

    HDFS-8852. HDFS architecture documentation of version 2.x is outdated
    about append write support. (Ajith S via aajisaka)

    HDFS-8867. Enable optimized block reports. (Daryn Sharp via jing9)

    HDFS-8891. HDFS concat should keep srcs order. (Yong Zhang via jing9)

    HDFS-8879. Quota by storage type usage incorrectly initialized upon namenode
    restart. (xyao)

    HDFS-8950. NameNode refresh doesn't remove DataNodes that are no longer in
    the allowed list (Daniel Templeton)

    HDFS-8995. Flaw in registration bookeeping can make DN die on reconnect.
    (Kihwal Lee via yliu)

    HDFS-9033. dfsadmin -metasave prints "NaN" for cache used%.
    (Brahma Reddy Battula via aajisaka)

    HDFS-9042. Update document for the Storage policy name
    (J.Andreina via vinayakumarb)

    HDFS-9043. Doc updation for commands in HDFS Federation
    (J.Andreina via vinayakumab)

    HDFS-9083. Replication violates block placement policy (Rushabh Shah)

    HDFS-9106. Transfer failure during pipeline recovery causes permanent
    write failures (kihwal)

    HDFS-8850. VolumeScanner thread exits with exception if there is no block
    pool to be scanned but there are suspicious blocks. (Colin Patrick McCabe
    via yliu)

    HDFS-9178. Slow datanode I/O can cause a wrong node to be marked bad
    (kihwal)

    HDFS-8676. Delayed rolling upgrade finalization can cause heartbeat
    expiration. (Walter Su via kihwal)

    HDFS-9220. Reading small file (< 512 bytes) that is open for append fails
    due to incorrect checksum (Jing Zhao via kihwal)

    HDFS-9290. DFSClient#callAppend() is not backward compatible for slightly
    older NameNodes. (Tony Wu via kihwal)

    HDFS-9305. Delayed heartbeat processing causes storm of subsequent
    heartbeats. (Arpit Agarwal)

    HDFS-9317. Document fsck -blockId and -storagepolicy options in branch-2.7.
    (aajisaka)

    HDFS-9413. getContentSummary() on standby should throw StandbyException.
    (Brahma Reddy Battula via mingma)

    HDFS-9426. Rollingupgrade finalization is not backward compatible
    (Kihwal Lee via vinayakumarb)

    HDFS-9445. Datanode may deadlock while handling a bad volume.
    (Wlater Su via Kihwal)

    HDFS-8767. RawLocalFileSystem.listStatus() returns null for UNIX pipefile.
    (Kanaka Kumar Avvaru via wheat9)

Release 2.7.1 - 2015-07-06

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

    HDFS-8081. Split getAdditionalBlock() into two methods. (shv)

    HDFS-7931. DistributedFileSystem should not look for keyProvider in
    cache if Encryption is disabled (asuresh)

    HDFS-8204. Mover/Balancer should not schedule two replicas to the same
    datanode.  (Walter Su via szetszwo)

    HDFS-7770. Need document for storage type label of data node storage
    locations under dfs.data.dir. (Xiaoyu Yao via aajisaka)

    HDFS-8213. DFSClient should use hdfs.client.htrace HTrace configuration
    prefix rather than hadoop.htrace (cmccabe)

    HDFS-8521. Add VisibleForTesting annotation to
    BlockPoolSlice#selectReplicaToDelete. (cmccabe)

    HDFS-8361. Choose SSD over DISK in block placement.  (szetszwo)

    HDFS-7546. Document, and set an accepting default for
    dfs.namenode.kerberos.principal.pattern (Harsh J via aw)

  OPTIMIZATIONS

    HDFS-7164. Feature documentation for HDFS-6581. (Arpit Agarwal)

  OPTIMIZATIONS

  BUG FIXES

    HDFS-8151. Always use snapshot path as source when invalid snapshot names
    are used for diff based distcp. (jing9)

    HDFS-7934. Update RollingUpgrade rollback documentation: should use
    bootstrapstandby for standby NN. (J. Andreina via jing9)

    HDFS-8149. The footer of the Web UI "Hadoop, 2014" is old.
    (Brahma Reddy Battula via aajisaka)

    HDFS-8153. Error Message points to wrong parent directory in case of
    path component name length error (Anu Engineer via jitendra)

    HDFS-8179. DFSClient#getServerDefaults returns null within 1
    hour of system start. (Xiaoyu Yao via Arpit Agarwal)

    HDFS-8163. Using monotonicNow for block report scheduling causes
    test failures on recently restarted systems. (Arpit Agarwal)

    HDFS-8147. StorageGroup in Dispatcher should override equals nad hashCode.
    (surendra singh lilhore via szetszwo)

    HDFS-8273. FSNamesystem#Delete() should not call logSync() when holding the
    lock. (wheat9)

    HDFS-8269. getBlockLocations() does not resolve the .reserved path and
    generates incorrect edit logs when updating the atime. (wheat9)

    HDFS-8091: ACLStatus and XAttributes should be presented to
    INodeAttributesProvider before returning to client (asuresh)

    HDFS-8305: HDFS INotify: the destination field of RenameOp should always
    end with the file name (cmccabe)

    HDFS-8226. Non-HA rollback compatibility broken (J.Andreina via vinayakumarb)

    HDFS-7916. 'reportBadBlocks' from datanodes to standby Node BPServiceActor
    goes for infinite loop (Rushabh S Shah  via kihwal)

    HDFS-6300. Prevent multiple balancers from running simultaneously
    (Rakesh R via vinayakumarb)

    HDFS-8405. Fix a typo in NamenodeFsck.  (Takanobu Asanuma via szetszwo)

    HDFS-8451. DFSClient probe for encryption testing interprets empty URI
    property for "enabled". (Steve Loughran via xyao)

    HDFS-5215. dfs.datanode.du.reserved is not considered while computing
    available space ( Brahma Reddy Battula via Yongjun Zhang)

    HDFS-8523. Remove usage information on unsupported operation
    "fsck -showprogress" from branch-2 (J.Andreina via vinayakumarb)

    HDFS-8522. Change heavily recorded NN logs from INFO to DEBUG level. (xyao)

    HDFS-8566. HDFS documentation about debug commands wrongly identifies them
    as "hdfs dfs" commands (Surendra Singh Lilhore via Colin P. McCabe)

    HDFS-8583. Document that NFS gateway does not work with rpcbind
    on SLES 11. (Arpit Agarwal)

    HDFS-8572. DN always uses HTTP/localhost@REALM principals in SPNEGO.
    (wheat9)

    HDFS-8596. TestDistributedFileSystem et al tests are broken in branch-2
    due to incorrect setting of "datanode" attribute. (Yongjun Zhang)

    HDFS-8595. TestCommitBlockSynchronization fails in branch-2.7. (Patch
    applies to all branches). (Arpit Agarwal)

    HDFS-8600. TestWebHdfsFileSystemContract.testGetFileBlockLocations fails
    in branch-2.7. (Arpit Agarwal)

    HDFS-8576.  Lease recovery should return true if the lease can be released
    and the file can be closed.  (J.Andreina via szetszwo)

    HDFS-8544. Incorrect port specified in HFTP Guide document in branch-2.
    (Brahma Reddy Battula via Yongjun Zhang)

    HDFS-8597. Fix TestFSImage#testZeroBlockSize on Windows. (Xiaoyu Yao)

    HDFS-4660. Block corruption can happen during pipeline recovery (kihwal)

    HDFS-8633. Fix setting of dfs.datanode.readahead.bytes in hdfs-default.xml
    to match DFSConfigKeys. (Ray Chiang via Yongjun Zhang)

    HDFS-8626. Reserved RBW space is not released if creation of RBW File
    fails. (kanaka kumar avvaru via Arpit Agarwal)

    HDFS-8681. BlockScanner is incorrectly disabled by default.
    (Arpit Agarwal)

Release 2.7.0 - 2015-04-20

  INCOMPATIBLE CHANGES

  NEW FEATURES
    
    HDFS-6663. Admin command to track file and locations from block id.
    (Chen He via kihwal)

    HDFS-6982. nntop: top­-like tool for name node users.
    (Maysam Yabandeh via wang)

    HDFS-7424. Add web UI for NFS gateway (brandonli)
    
    HDFS-7449. Add metrics to NFS gateway (brandonli)

    HDFS-3107. Introduce truncate. (Plamen Jeliazkov via shv)

    HDFS-7056. Snapshot support for truncate. (Plamen Jeliazkov and shv)

    HDFS-6673. Add delimited format support to PB OIV tool. (Eddy Xu via wang)

    HDFS-7655. Expose truncate API for Web HDFS. (yliu)

    HDFS-6133. Add a feature for replica pinning so that a pinned replica
    will not be moved by Balancer/Mover.  (zhaoyunjiong via szetszwo)

    HDFS-3689. Add support for variable length block. Contributed by Jing Zhao.

    HDFS-7584. Enable Quota Support for Storage Types (See breakdown of
    tasks below)

    HDFS-7656. Expose truncate API for HDFS httpfs. (yliu)

    HDFS-6488. Support HDFS superuser in NFS gateway. (brandonli)

    HDFS-7838. Expose truncate API for libhdfs. (yliu)

    HDFS-6826. Plugin interface to enable delegation of HDFS authorization 
    assertions. (Arun Suresh via jitendra)

  IMPROVEMENTS

    HDFS-7752. Improve description for
    "dfs.namenode.num.extra.edits.retained"
    and "dfs.namenode.num.checkpoints.retained" properties on
    hdfs-default.xml (Wellington Chevreuil via harsh)

    HDFS-7055. Add tracing to DFSInputStream (cmccabe)

    HDFS-7186. Document the "hadoop trace" command. (Masatake Iwasaki via Colin
    P. McCabe)

    HDFS-7202. Should be able to omit package name of SpanReceiver on "hadoop
    trace -add" (iwasakims via cmccabe)

    HDFS-7026. Introduce a string constant for "Failed to obtain user group
    info...". (Yongjun Zhang via atm)

    HDFS-7209. Populate EDEK cache when creating encryption zone. (Yi Liu via wang)

    HDFS-6252. Phase out the old web UI in HDFS. (wheat9)

    HDFS-7266. HDFS Peercache enabled check should not lock on object (awang
    via cmccabe)

    HDFS-7254. Add documentation for hot swaping DataNode drives (Lei Xu via
    Colin P. McCabe)

    HDFS-6877. Avoid calling checkDisk when an HDFS volume is removed during a
    write. (Lei Xu via Colin P. McCabe)

    HDFS-2486. Remove unnecessary priority level checks in
    UnderReplicatedBlocks.  (Uma Maheswara Rao G via szetszwo)

    HDFS-6824. Additional user documentation for HDFS encryption. (wang)

    HDFS-7165. Separate block metrics for files with replication count 1.
    (Zhe Zhang via wang)

    HDFS-7222. Expose DataNode network errors as a metric. (Charles Lamb via wang)

    HDFS-7257. Add the time of last HA state transition to NN's /jmx page.
    (Charles Lamb via wheat9)

    HDFS-7223. Tracing span description of IPC client is too long (iwasakims
    via cmccabe)

    HDFS-7283. Bump DataNode OOM log from WARN to ERROR.
    (Stephen Chu via wheat9)

    HDFS-5928. Show namespace and namenode ID on NN dfshealth page.
    (Siqi Li via wheat9)

    HDFS-7280. Use netty 4 in WebImageViewer. (wheat9)

    HDFS-3342. SocketTimeoutException in BlockSender.sendChunks could
    have a better error message. (Yongjun Zhang via wang)

    HDFS-6917. Add an hdfs debug command to validate blocks, call recoverlease,
    etc. (cmccabe)

    HDFS-7356. Use DirectoryListing.hasMore() directly in nfs. (Li Lu via jing9)

    HDFS-7357. FSNamesystem.checkFileProgress should log file path.
    (Tsz Wo Nicholas Sze via wheat9)

    HDFS-7335. Redundant checkOperation() in FSN.analyzeFileState().
    (Milan Desai via shv)

    HDFS-7333. Improve logging in Storage.tryLock(). (shv)

    HDFS-7361. TestCheckpoint fails after change of log message related to
    locking violation. (shv)

    HDFS-7329. Improve logging when MiniDFSCluster fails to start.
    (Byron Wong via shv)

    HDFS-7336. Unused member DFSInputStream.buffersize. (Milan Desai via shv)

    HDFS-7365. Remove hdfs.server.blockmanagement.MutableBlockCollection.
    (Li Lu via wheat9)

    HDFS-7381. Decouple the management of block id and gen stamps from
    FSNamesystem. (wheat9)

    HDFS-7375. Move FSClusterStats to o.a.h.h.hdfs.server.blockmanagement.
    (wheat9)

    HDFS-7386. Replace check "port number < 1024" with shared isPrivilegedPort
    method. (Yongjun Zhang via cnauroth)

    HDFS-7394. Log at INFO level, not WARN level, when InvalidToken is seen in
    ShortCircuitCache (Keith Pak via Colin P. McCabe)

    HDFS-7279. Use netty to implement DatanodeWebHdfsMethods. (wheat9)

    HDFS-7404. Remove o.a.h.hdfs.server.datanode.web.resources.
    (Li Lu via wheat9)

    HDFS-7398. Reset cached thread-local FSEditLogOp's on every
    FSEditLog#logEdit. (Gera Shegalov via cnauroth)

    HDFS-7409. Allow dead nodes to finish decommissioning if all files are
    fully replicated. (wang)

    HDFS-7413. Some unit tests should use NameNodeProtocols instead of
    FSNameSystem. (wheat9)

    HDFS-7415. Move FSNameSystem.resolvePath() to FSDirectory. (wheat9)

    HDFS-7420. Delegate permission checks to FSDirectory. (wheat9)

    HDFS-7331. Add Datanode network counts to datanode jmx page. (Charles Lamb
    via atm)

    HDFS-7412. Move RetryCache to NameNodeRpcServer. (wheat9)

    HDFS-7419. Improve error messages for DataNode hot swap drive feature (Lei
    Xu via Colin P. Mccabe)

    HDFS-7436. Consolidate implementation of concat(). (wheat9)

    HDFS-7440. Consolidate snapshot related operations in a single class.
    (wheat9)

    HDFS-6803 Document DFSClient#DFSInputStream expectations reading and preading
    in concurrent context. (stack via stevel)

    HDFS-7310. Mover can give first priority to local DN if it has target storage type 
    available in local DN. (Vinayakumar B via umamahesh)

    HDFS-7210. Avoid two separate RPC's namenode.append() and namenode.getFileInfo() 
    for an append call from DFSClient. (Vinayakumar B via umamahesh)

    HDFS-7450. Consolidate the implementation of GetFileInfo(), GetListings() and
    GetContentSummary() into a single class. (wheat9)

    HDFS-7438. Consolidate the implementation of rename() into a single class.
    (wheat9)

    HDFS-7462. Consolidate implementation of mkdirs() into a single class.
    (wheat9)

    HDFS-6735. A minor optimization to avoid pread() be blocked by read()
    inside the same DFSInputStream (Lars Hofhansl via stack)
    
    HDFS-7458. Add description to the nfs ports in core-site.xml used by nfs
    test to avoid confusion (Yongjun Zhang via brandonli)

    HDFS-7468. Moving verify* functions to corresponding classes.
    (Li Lu via wheat9)

    HDFS-7478. Move org.apache.hadoop.hdfs.server.namenode.NNConf to
    FSNamesystem. (Li Lu via wheat9)

    HDFS-7474. Avoid resolving path in FSPermissionChecker. (jing9)

    HDFS-7459. Consolidate cache-related implementation in FSNamesystem into
    a single class. (wheat9)

    HDFS-7476. Consolidate ACL-related operations to a single class.
    (wheat9 via cnauroth)

    HDFS-7384. 'getfacl' command and 'getAclStatus' output should be in sync.
    (Vinayakumar B via cnauroth)

    HDFS-7486. Consolidate XAttr-related implementation into a single class.
    (wheat9)

    HDFS-7498. Simplify the logic in INodesInPath. (jing9)

    HDFS-7463. Simplify FSNamesystem#getBlockLocationsUpdateTimes. (wheat9)

    HDFS-7509. Avoid resolving path multiple times. (jing9)

    HDFS-7426. Change nntop JMX format to be a JSON blob. (wang)

    HDFS-7513. HDFS inotify: add defaultBlockSize to CreateEvent (cmccabe)

    HDFS-7536. Remove unused CryptoCodec in org.apache.hadoop.fs.Hdfs.
    (Yi Liu via wheat9)

    HDFS-7528. Consolidate symlink-related implementation into a single class.
    (wheat9)

    HDFS-7373. Clean up temporary files after fsimage transfer failures.
    (kihwal)

    HDFS-7543. Avoid path resolution when getting FileStatus for audit logs.
    (wheat9)

    HDFS-7530. Allow renaming of encryption zone roots. (Charles Lamb via wang)

    HDFS-7484. Make FSDirectory#addINode take existing INodes as its parameter.
    (jing9)

    HADOOP-11032. Replace use of Guava's Stopwatch with Hadoop's StopWatch
    (ozawa)

    HADOOP-11470. Remove some uses of obsolete guava APIs from the hadoop
    codebase. (Sangjin Lee via Colin P. McCabe)

    HDFS-7323. Move the get/setStoragePolicy commands out from dfsadmin.
    (jing9 via yliu)

    HDFS-7326: Add documentation for hdfs debug commands (Vijay Bhat via Colin
    P. McCabe)

    HDFS-7598. Remove dependency on old version of guava in
    TestDFSClientCache#testEviction. (Sangjin Lee via Colin P. McCabe)

    HDFS-7600. Refine hdfs admin classes to reuse common code. (jing9)

    HDFS-2219. Change fsck to support fully qualified paths so that a 
    particular namenode in a federated cluster with multiple namenodes
    can be specified in the path parameter.  (szetszwo)

    HDFS-7457. DatanodeID generates excessive garbage. (daryn via kihwal)

    HDFS-7189. Add trace spans for DFSClient metadata operations. (Colin P.
    McCabe via yliu)

    HDFS-7591. hdfs classpath command should support same options as hadoop
    classpath. (Varun Saxena via Arpit Agarwal)

    HDFS-7573. Consolidate the implementation of delete() into a single class.
    (wheat9)

    HDFS-7640. Print NFS Client in the NFS log. (Brandon Li via wheat9)

    HDFS-7623. Add htrace configuration properties to core-default.xml and
    update user doc about how to enable htrace. (yliu)

    HDFS-7224. Allow reuse of NN connections via webhdfs (Eric Payne via
    kihwal)

    HDFS-7683. Combine usages and percent stats in NameNode UI.
    (Vinayakumar B via wheat9)

    HDFS-7675. Remove unused member DFSClient#spanReceiverHost (cmccabe)

    HDFS-7603. The background replication queue initialization may not let
    others run (kihwal)

    HDFS-7706. Switch BlockManager logging to use slf4j. (wang)

    HDFS-5631. Change BlockMetadataHeader.readHeader(..), ChunkChecksum
    class and constructor to public; and fix FsDatasetSpi to use generic type
    instead of FsVolumeImpl.  (David Powell and Joe Pallas via szetszwo)

    HDFS-5782. Change BlockListAsLongs constructor to take Replica as parameter
    type instead of concrete classes Block and ReplicaInfo.  (David Powell
    and Joe Pallas via szetszwo)

    HDFS-7681. Change ReplicaInputStreams constructor to take InputStream(s)
    instead of FileDescriptor(s).  (Joe Pallas via szetszwo)

    HDFS-7712. Switch blockStateChangeLog to use slf4j. (wang)

    HDFS-7270. Add congestion signaling capability to DataNode write protocol.
    (wheat9)

    HDFS-7732. Fix the order of the parameters in DFSConfigKeys.
    (Brahma Reddy Battula via aajisaka)

    HDFS-7710. Remove dead code in BackupImage.java. (Xiaoyu Yao via aajisaka)

    HDFS-7738. Revise the exception message for recover lease; add more truncate
    tests such as truncate with HA setup, negative tests, truncate with other
    operations and multiple truncates.  (szetszwo)

    HDFS-7743. Code cleanup of BlockInfo and rename BlockInfo to
    BlockInfoContiguous. (jing9)

    HDFS-7058. Tests for truncate CLI. (Dasha Boudnik via shv)

    HDFS-7760. Document truncate for WebHDFS. (shv)

    HDFS-7761. cleanup unnecssary code logic in LocatedBlock. (yliu)

    HDFS-7703. Support favouredNodes for the append for new blocks
    (vinayakumarb)

    HDFS-7694. FSDataInputStream should support "unbuffer" (cmccabe)

    HDFS-7684. The host:port settings of the daemons should be trimmed before
    use. (Anu Engineer via aajisaka)

    HDFS-7790. Do not create optional fields in DFSInputStream unless they are
    needed (cmccabe)

    HDFS-316. Balancer should run for a configurable # of iterations (Xiaoyu
    Yao via aw)

    HDFS-7430. Refactor the BlockScanner to use O(1) memory and use multiple
    threads (cmccabe)

    HDFS-7604. Track and display failed DataNode storage locations in NameNode.
    (cnauroth)

    HDFS-7797. Add audit log for setQuota operation (Rakesh R via umamahesh)

    HDFS-4266. BKJM: Separate write and ack quorum (Rakesh R via umamahesh)

    HDFS-7795. Show warning if not all favored nodes were chosen by namenode
    (kihwal)

    HDFS-7780. Update use of Iterator to Iterable in DataXceiverServer and
    SnapshotDiffInfo. (Ray Chiang via aajisaka)

    HDFS-7772. Document hdfs balancer -exclude/-include option in
    HDFSCommands.html (Xiaoyu Yao via cnauroth)

    HDFS-7773. Additional metrics in HDFS to be accessed via jmx.
    (Anu Engineer via cnauroth)

    HDFS-7740. Test truncate with DataNodes restarting. (yliu)

    HDFS-7668. Convert site documentation from apt to markdown (Masatake
    Iwasaki via Colin P. McCabe)

    HDFS-7495. Remove updatePosition argument from DFSInputStream#getBlockAt()
    (cmccabe)

    HDFS-7537. Add "UNDER MIN REPL'D BLOCKS" count to fsck.  (GAO Rui via
    szetszwo)

    HDFS-7832. Show 'Last Modified' in Namenode's 'Browse Filesystem'
    (vinayakumarb)

    HDFS-7819. Log WARN message for the blocks which are not in Block ID based
    layout (Rakesh R via Colin P. McCabe)

    HDFS-7308. Change the packet chunk size computation in DFSOutputStream in
    order to enforce packet size <= 64kB.  (Takuya Fukudome via szetszwo)

    HDFS-7685. Document dfs.namenode.heartbeat.recheck-interval in
    hdfs-default.xml. (Kai Sasaki via aajisaka)

    HDFS-5853. Add "hadoop.user.group.metrics.percentiles.intervals" to
    hdfs-default.xml. (aajisaka)

    HDFS-7439. Add BlockOpResponseProto's message to the exception messages.
    (Takanobu Asanuma via szetszwo)

    HDFS-7789. DFSck should resolve the path to support cross-FS symlinks.
    (gera)

    HDFS-7535. Utilize Snapshot diff report for distcp. (jing9)

    HDFS-1522. Combine two BLOCK_FILE_PREFIX constants into one.
    (Dongming Liang via shv)

    HDFS-7746. Add a test randomly mixing append, truncate and snapshot
    operations. (szetszwo)

    HADOOP-11648. Set DomainSocketWatcher thread name explicitly.
    (Liang Xie via ozawa)

    HDFS-7855. Separate class Packet from DFSOutputStream. (Li Bo bia jing9)

    HDFS-7411. Change decommission logic to throttle by blocks rather than
    nodes in each interval. (Andrew Wang via cdouglas)

    HDFS-7898. Change TestAppendSnapshotTruncate to fail-fast.
    (Tsz Wo Nicholas Sze via jing9)

    HDFS-6806. HDFS Rolling upgrade document should mention the versions
    available. (J.Andreina via aajisaka)

    HDFS-7491. Add incremental blockreport latency to DN metrics.
    (Ming Ma via cnauroth)

    HDFS-7435. PB encoding of block reports is very inefficient.
    (Daryn Sharp via kihwal)

    HDFS-2605. Remove redundant "Release 0.21.1" section from CHANGES.txt.
    (Allen Wittenauer via shv)

    HDFS-7940. Add tracing to DFSClient#setQuotaByStorageType (Rakesh R via
    Colin P. McCabe)

    HDFS-7054. Make DFSOutputStream tracing more fine-grained (cmccabe)

    HDFS.7849. Update documentation for enabling a new feature in rolling
    upgrade ( J.Andreina via vinayakumarb )

    HDFS-7962. Remove duplicated logs in BlockManager. (yliu)

    HDFS-7917. Use file to replace data dirs in test to simulate a disk failure.
    (Lei (Eddy) Xu via cnauroth)

    HDFS-7956. Improve logging for DatanodeRegistration.
    (Plamen Jeliazkov via shv)

    HDFS-7976. Update NFS user guide for mount option "sync" to minimize or
    avoid reordered writes. (brandonli)

    HDFS-7410. Support CreateFlags with append() to support hsync() for
    appending streams (Vinayakumar B via Colin P. McCabe)

    HDFS-7811. Avoid recursive call getStoragePolicyID in
    INodeFile#computeQuotaUsage. (Xiaoyu Yao and jing9)

    HDFS-8071. Redundant checkFileProgress() in PART II of getAdditionalBlock().
    (shv)

  OPTIMIZATIONS

    HDFS-7454. Reduce memory footprint for AclEntries in NameNode.
    (Vinayakumar B via wheat9)

    HDFS-7615. Remove longReadLock (kihwal)

  BUG FIXES

    HDFS-6741. Improve permission denied message when
    FSPermissionChecker#checkOwner fails (Stephen Chu and harsh).

    HDFS-6538. Comment format error in ShortCircuitRegistry javadoc.
    (David Luo via harsh).

    HDFS-7194. Fix findbugs "inefficient new String constructor" warning in
    DFSClient#PATH (yzhang via cmccabe)

    HDFS-7198. Fix or suppress findbugs "unchecked conversion" warning in
    DFSClient#getPathTraceScope (cmccabe)

    HDFS-6657. Remove link to 'Legacy UI' in the Namenode UI.
    (Vinayakumar B via wheat9)

    HDFS-7201. Fix typos in hdfs-default.xml. (Dawson Choong via wheat9)

    HDFS-7190. Bad use of Preconditions in startFileInternal().
    (Dawson Choong via wheat9)

    HDFS-7242. Code improvement for FSN#checkUnreadableBySuperuser.
    (Yi Liu via vinayakumarb)

    HDFS-7252. small refinement to the use of isInAnEZ in FSNamesystem.
    (Yi Liu via vinayakumarb)

    HDFS-7277. Remove explicit dependency on netty 3.2 in BKJournal. (wheat9)

    HDFS-7232. Populate hostname in httpfs audit log (Zoran Dimitrijevic
    via aw)

    HDFS-7258. CacheReplicationMonitor rescan schedule log should use DEBUG
    level instead of INFO level. (Xiaoyu Yao via wheat9)

    HDFS-7282. Fix intermittent TestShortCircuitCache and
    TestBlockReaderFactory failures resulting from TemporarySocketDirectory GC.
    (Jinghui Wang via Colin Patrick McCabe)

    HDFS-7301. TestMissingBlocksAlert should use MXBeans instead of old web UI.
    (Zhe Zhang via wheat9)

    HDFS-7315. DFSTestUtil.readFileBuffer opens extra FSDataInputStream.
    (Plamen Jeliazkov via wheat9)

    HDFS-7324. haadmin command usage prints incorrect command name.
    (Brahma Reddy Battula via suresh)

    HDFS-7366. BlockInfo should take replication as an short in the constructor.
    (Li Lu via wheat9)

    HDFS-7389. Named user ACL cannot stop the user from accessing the FS entity.
    (Vinayakumar B via cnauroth)

    HDFS-6938. Cleanup javac warnings in FSNamesystem (Charles Lamb via wheat9)

    HDFS-7358. Clients may get stuck waiting when using ByteArrayManager.
    (szetszwo)

    HDFS-7395. BlockIdManager#clear() bails out when resetting the
    GenerationStampV1Limit. (wheat9)

    HDFS-7399. Lack of synchronization in
    DFSOutputStream#Packet#getLastByteOffsetBlock() (vinayakumarb)

    HDFS-7146. NFS ID/Group lookup requires SSSD enumeration on the server
    (Yongjun Zhang via brandonli)

    HDFS-7406. SimpleHttpProxyHandler puts incorrect "Connection: Close"
    header. (wheat9)

    HDFS-7374. Allow decommissioning of dead DataNodes. (Zhe Zhang)

    HDFS-7403. Inaccurate javadoc of BlockUCState#COMPLETE state. (
    Yongjun Zhang via yliu)

    HDFS-7303. NN UI fails to distinguish datanodes on the same host.
    (Benoy Antony via wheat9)

    HDFS-7097. Allow block reports to be processed during checkpointing on
    standby name node. (kihwal via wang)

    HDFS-7444. convertToBlockUnderConstruction should preserve BlockCollection.
    (wheat9)

    HDFS-7448 TestBookKeeperHACheckpoints fails in trunk build
    (Akira Ajisaka via stevel)

    HDFS-7472. Fix typo in message of ReplicaNotFoundException.
    (Masatake Iwasaki via wheat9)

    HDFS-7473. Document setting dfs.namenode.fs-limits.max-directory-items to 0
    is invalid. (Akira AJISAKA via cnauroth)

    HDFS-7481. Add ACL indicator to the "Permission Denied" exception.
    (vinayakumarb)

    HDFS-7502. Fix findbugs warning in hdfs-nfs project.
    (Brandon Li via wheat9)

    HDFS-5578. [JDK8] Fix Javadoc errors caused by incorrect or illegal tags
    in doc comments. (Andrew Purtell via wheat9)

    HDFS-7475. Make TestLazyPersistFiles#testLazyPersistBlocksAreSaved
    deterministic. (Xiaoyu Yao via Arpit Agarwal)

    HDFS-7515. Fix new findbugs warnings in hadoop-hdfs. (wheat9)

    HDFS-7497. Inconsistent report of decommissioning DataNodes between
    dfsadmin and NameNode webui. (Yongjun Zhang via wang)

    HDFS-7517. Remove redundant non-null checks in FSNamesystem#
    getBlockLocations. (wheat9)

    HDFS-7514. TestTextCommand fails on Windows. (Arpit Agarwal)

    HDFS-7506. Consolidate implementation of setting inode attributes into a
    single class. (wheat9)
    
    HDFS-7516. Fix findbugs warnings in hdfs-nfs project. (brandonli)

    HDFS-6425. Large postponedMisreplicatedBlocks has impact on blockReport
    latency. (Ming Ma via kihwal)

    HDFS-7494. Checking of closed in DFSInputStream#pread() should be protected
    by synchronization (Ted Yu via Colin P. McCabe)

    HDFS-7431. log message for InvalidMagicNumberException may be incorrect.
    (Yi Liu via cnauroth)

    HDFS-7557. Fix spacing for a few keys in DFSConfigKeys.java 
    (Colin P.McCabe)

    HDFS-7560. ACLs removed by removeDefaultAcl() will be back after NameNode
    restart/failover. (Vinayakumar B via cnauroth)

    HDFS-7456. De-duplicate AclFeature instances with same AclEntries do reduce
    memory footprint of NameNode (vinayakumarb)

    HDFS-7563. NFS gateway parseStaticMap NumberFormatException 
    (Yongjun Zhang via brandonli)

    HDFS-7572. TestLazyPersistFiles#testDnRestartWithSavedReplicas is flaky on
    Windows. (Arpit Agarwal via cnauroth)

    HDFS-7583. Fix findbug in TransferFsImage.java (vinayakumarb)

    HDFS-7564. NFS gateway dynamically reload UID/GID mapping file /etc/nfs.map
    (Yongjun Zhang via brandonli)

    HDFS-7561. TestFetchImage should write fetched-image-dir under target.
    (Liang Xie via shv)

    HDFS-7589. Break the dependency between libnative_mini_dfs and libhdfs.
    (Zhanwei Wang via cnauroth)

    HDFS-5445. PacketReceiver populates the packetLen field in PacketHeader
    incorrectly (Jonathan Mace via Colin P. McCabe)

    HDFS-7585. Get TestEnhancedByteBufferAccess working on CPU architectures
    with page sizes other than 4096 (Sam Liu via Colin P. McCabe)

    HDFS-7635. Remove TestCorruptFilesJsp from branch-2. (cnauroth)

    HDFS-7632. MiniDFSCluster configures DataNode data directories incorrectly if
    using more than 1 DataNode and more than 2 storage locations per DataNode.
    (cnauroth)

    HDFS-7637. Fix the check condition for reserved path. (Yi Liu via jing9)

    HDFS-7641. Update archival storage user doc for list/set/get block storage
    policies. (yliu)

    HDFS-7496. Fix FsVolume removal race conditions on the DataNode by
    reference-counting the volume instances (lei via cmccabe)

    HDFS-7548. Corrupt block reporting delayed until datablock scanner thread
    detects it (Rushabh Shah via kihwal)

    HDFS-3519. Checkpoint upload may interfere with a concurrent saveNamespace.
    (Ming Ma via cnauroth)

    HDFS-7644. minor typo in HttpFS doc (Charles Lamb via aw)

    HDFS-7606. Fix potential NPE in INodeFile.getBlocks(). (Byron Wong via shv)

    HDFS-7638: Small fix and few refinements for FSN#truncate. (yliu)

    HDFS-7634. Disallow truncation of Lazy persist files. (Yi Liu via
    Arpit Agarwal)

    HDFS-7643. Test case to ensure lazy persist files cannot be truncated.
    (Yi Liu via Arpit Agarwal)

    HDFS-7659. truncate should check negative value of the new length.
    (Yi Liu via shv)

    HDFS-7676. Fix TestFileTruncate to avoid bug of HDFS-7611. (shv)

    HDFS-49. MiniDFSCluster.stopDataNode will always shut down a node in
    the cluster if a matching name is not found. (stevel)

    HDFS-7566. Remove obsolete entries from hdfs-default.xml (Ray Chiang
    via aw)

    HDFS-7677. DistributedFileSystem#truncate should resolve symlinks. (yliu)

    HDFS-7611. deleteSnapshot and delete of a file can leave orphaned blocks
    in the blocksMap on NameNode restart. (jing9 and Byron Wong)

    HDFS-7423. various typos and message formatting fixes in nfs daemon and
    doc. (Charles Lamb via yliu)

    HDFS-7696. In FsDatasetImpl, the getBlockInputStream(..) and
    getTmpInputStreams(..) methods may leak file descriptors.  (szetszwo)

    HDFS-6651. Deletion failure can leak inodes permanently.
    (Jing Zhao via wheat9)

    HDFS-7734. Class cast exception in NameNode#main. (yliu via wang)

    HDFS-7719. BlockPoolSliceStorage#removeVolumes fails to remove some
    in-memory state associated with volumes. (Lei (Eddy) Xu via Colin P.
    McCabe)

    HDFS-7709. Fix findbug warnings in httpfs. (Rakesh R via ozawa)

    HDFS-7698. Fix locking on HDFS read statistics and add a method for
    clearing them. (Colin P. McCabe via yliu)

    HDFS-7741. Remove unnecessary synchronized in FSDataInputStream and
    HdfsDataInputStream. (yliu)

    HDFS-7647. DatanodeManager.sortLocatedBlocks sorts DatanodeInfos
    but not StorageIDs. (Milan Desai via Arpit Agarwal)

    HDFS-7756. Restore method signature for LocatedBlock#getLocations(). (Ted
    Yu via yliu)

    HDFS-7744. Fix potential NPE in DFSInputStream after setDropBehind or
    setReadahead is called (cmccabe)

    HDFS-7718. Store KeyProvider in ClientContext to avoid leaking key provider
    threads when using FileContext (Arun Suresh via Colin P. McCabe)

    HDFS-7769. TestHDFSCLI should not create files in hdfs project root dir.
    (szetszwo)

    HDFS-7753. Fix Multithreaded correctness Warnings in BackupImage.
    (Rakesh R and shv)

    HDFS-7751. Fix TestHDFSCLI for quota with storage type.  (Xiaoyu Yao
    via szetszwo)

    HDFS-7736. Fix typos in dfsadmin/fsck/snapshotDiff usage messages.
    (Brahma Reddy Battula via wheat9)

    HDFS-7771. fuse_dfs should permit FILE: on the front of KRB5CCNAME
    (cmccabe)

    HDFS-7704. DN heartbeat to Active NN may be blocked and expire if
    connection to Standby NN continues to time out (Rushabh Shah via kihwal)

    HDFS-7721. The HDFS BlockScanner may run fast during the first hour
    (cmccabe)

    HDFS-7686. Re-add rapid rescan of possibly corrupt block feature to the
    block scanner (cmccabe)

    HDFS-7778. Rename FsVolumeListTest to TestFsVolumeList and commit it to
    branch-2. (Lei (Eddy) Xu via cnauroth)

    HDFS-4625. BKJM doesn't take advantage of speculative reads. (Rakesh R
    via aajisaka)

    HDFS-7798. Checkpointing failure caused by shared KerberosAuthenticator.
    (Chengbing Liu via yliu)

    HDFS-6662. WebHDFS cannot open a file if its path contains "%".
    (Gerson Carlos via wheat9)

    HDFS-7814. Fix usage string of storageType parameter for
    "dfsadmin -setSpaceQuota/clrSpaceQuota". (Xiaoyu Yao via cnauroth)

    HDFS-7807. libhdfs htable.c: fix htable resizing, add unit test (cmccabe)

    HDFS-7805. NameNode recovery prompt should be printed on console (Surendra
    Singh Lilhore via Colin P. McCabe)

    HDFS-7008. xlator should be closed upon exit from DFSAdmin#genericRefresh().
    (ozawa)

    HDFS-7831. Fix the starting index and end condition of the loop in
    FileDiffList.findEarlierSnapshotBlocks(). (Konstantin Shvachko via jing9)

    HDFS-7843. A truncated file is corrupted after rollback from a rolling
    upgrade.  (szetszwo)

    HDFS-7774. Unresolved symbols error while compiling HDFS on Windows 7/32 bit.
    (Kiran Kumar M R via cnauroth)

    HDFS-6753. Initialize checkDisk when DirectoryScanner not able to get
    files list for scanning (J.Andreina via vinayakumarb)

    HDFS-7785. Improve diagnostics information for HttpPutFailedException.
    (Chengbing Liu via wheat9)

    HDFS-7757. Misleading error messages in FSImage.java. (Brahma Reddy Battula
    via Arpit Agarwal)

    HDFS-6565. Use jackson instead jetty json in hdfs-client.
    (Akira Ajisaka via wheat9)

    HDFS-7682. {{DistributedFileSystem#getFileChecksum}} of a snapshotted file
    includes non-snapshotted content. (Charles Lamb via atm)

    HDFS-7869. Inconsistency in the return information while performing rolling
    upgrade ( J.Andreina via vinayakumarb )

    HDFS-7879. hdfs.dll does not export functions of the public libhdfs API.
    (Chris Nauroth via wheat9)

    HDFS-7434. DatanodeID hashCode should not be mutable. (daryn via kihwal)

    HDFS-7818. OffsetParam should return the default value instead of throwing
    NPE when the value is unspecified. (Eric Payne via wheat9)

    HDFS-7880. Remove the tests for legacy Web UI in branch-2.
    (Brahma Reddy Battula via aajisaka)

    HDFS-6833.  DirectoryScanner should not register a deleting block with
    memory of DataNode.  (Shinichi Yamashita via szetszwo)

    HDFS-7926. NameNode implementation of ClientProtocol.truncate(..) is not 
    idempotent (Tsz Wo Nicholas Sze via brandonli)

    HDFS-7903. Cannot recover block after truncate and delete snapshot.
    (Plamen Jeliazkov via shv)

    HDFS-7886. Fix TestFileTruncate falures. (Plamen Jeliazkov and shv)

    HDFS-7946. TestDataNodeVolumeFailureReporting NPE on Windows. (Xiaoyu Yao
    via Arpit Agarwal)

    HDFS-7953. NN Web UI fails to navigate to paths that contain #.
    (kanaka kumar avvaru via wheat9)

    HDFS-7948. TestDataNodeHotSwapVolumes#testAddVolumeFailures failed on
    Windows. (Xiaoyu Yao via Arpit Agarwal)

    HDFS-7950. Fix TestFsDatasetImpl#testAddVolumes failure on Windows.
    (Xiaoyu Yao via Arpit Agarwal)

    HDFS-7951. Fix NPE for
    TestFsDatasetImpl#testAddVolumeFailureReleasesInUseLock on Linux
    (Xiaoyu Yao via Arpit Agarwal)

    HDFS-7722. DataNode#checkDiskError should also remove Storage when error
    is found. (Lei Xu via Colin P. McCabe)

    HDFS-7697. Mark the PB OIV tool as experimental. (Lei Xu via wheat9)

    HDFS-7914. TestJournalNode#testFailToStartWithBadConfig fails when the
    default dfs.journalnode.http-address port 8480 is in use. (Xiaoyu Yao via
    Arpit Agarwal)

    HDFS-7945. The WebHdfs system on DN does not honor the length parameter.
    (wheat9)

    HDFS-7943. Append cannot handle the last block with length greater than
    the preferred block size. (jing9)

    HDFS-7816. Unable to open webhdfs paths with "+". (wheat9 via kihwal)

    HDFS-7932. Speed up the shutdown of datanode during rolling upgrade.(kihwal)

    HDFS-7957. Truncate should verify quota before making changes. (jing9)

    HDFS-6841. Use Time.monotonicNow() wherever applicable instead of Time.now()
    (Vinayakumar B via kihwal)

    HDFS-7942. NFS: support regexp grouping in nfs.exports.allowed.hosts (brandonli)

    HDFS-7961. Trigger full block report after hot swapping disk. (Eddy Xu via wang)

    HDFS-7977. NFS couldn't take percentile intervals (brandonli)

    HDFS-7963. Fix expected tracing spans in TestTracing along with HDFS-7054.
    (Masatake Iwasaki via kihwal)

    HDFS-7748. Separate ECN flags from the Status in the DataTransferPipelineAck.
    (Anu Engineer and Haohui Mai via wheat9)

    HDFS-8036. Use snapshot path as source when using snapshot diff report in
    DistCp. (Jing Zhao via wheat9)

    HDFS-8001 RpcProgramNfs3 : wrong parsing of dfs.blocksize
    (Remi Catherinot via brandonli)

    HDFS-7954. TestBalancer#testBalancerWithPinnedBlocks should not be executed
    on Windows.  (Xiaoyu Yao via szetszwo)

    HDFS-8039. Fix TestDebugAdmin#testRecoverLease and
    testVerifyBlockChecksumCommand on Windows. (Xiaoyu Yao via cnauroth)

    HDFS-7996. After swapping a volume, BlockReceiver reports
    ReplicaNotFoundException (Lei (Eddy) Xu via Colin P. McCabe)

    HDFS-8051. FsVolumeList#addVolume should release volume reference if not
    put it into BlockScanner. (Lei (Eddy) Xu via Colin P. McCabe)

    HDFS-8038. PBImageDelimitedTextWriter#getEntry output HDFS path in
    platform-specific format. (Xiaoyu Yao via cnauroth)

    HDFS-8025. Addendum fix for HDFS-3087 Decomissioning on NN restart can
    complete without blocks being replicated. (Ming Ma via wang)

    HDFS-8063: Fix intermittent test failures in TestTracing (Masatake Iwasaki
    via Colin P. McCabe)

    BREAKDOWN OF HDFS-7584 SUBTASKS AND RELATED JIRAS

      HDFS-7720. Quota by Storage Type API, tools and ClientNameNode
      Protocol changes. (Xiaoyu Yao via Arpit Agarwal)

      HDFS-7723. Quota By Storage Type namenode implemenation. (Xiaoyu Yao
      via Arpit Agarwal)

      HDFS-7751. Fix TestHDFSCLI for quota with storage type.  (Xiaoyu Yao
      via szetszwo)

      HDFS-7776. Adding additional unit tests for Quota By Storage Type.
      (Xiaoyu Yao via Arpit Agarwal)

      HDFS-7775. Use consistent naming for NN-internal quota related types
      and functions. (Xiaoyu Yao via Arpit Agarwal)

      HDFS-7806. Refactor: move StorageType from hadoop-hdfs to
      hadoop-common. (Xiaoyu Yao via Arpit Agarwal)

      HDFS-7824. GetContentSummary API and its namenode implementation for
      Storage Type Quota/Usage. (Xiaoyu Yao via Arpit Agarwal)

Release 2.6.5 - UNRELEASED

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

     HDFS-9629. Update the footer of Web UI to show year 2016
     (Xiao Chen and Vinayakumar B via vinayakumarb)

     HDFS-9688. Test the effect of nested encryption zones in HDFS downgrade.
     (zhz)

  OPTIMIZATIONS

  BUG FIXES

    HDFS-9347. Invariant assumption in TestQuorumJournalManager.shutdown()
    is wrong. (Wei-Chiu Chuang via zhz)

    HDFS-10271. Extra bytes are getting released from reservedSpace for append
    (Brahma Reddy Battula via vinayakumarb)

Release 2.6.4 - 2016-02-11

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

  OPTIMIZATIONS

  BUG FIXES

    HDFS-9600. do not check replication if the block is under construction
    (Phil Yang via vinayakumarb)

    HDFS-9294. DFSClient deadlock when close file and failed to renew lease.
    (Brahma Reddy Battula via szetszwo)

Release 2.6.3 - 2015-12-17

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

  OPTIMIZATIONS

  BUG FIXES

    HDFS-8615. Correct HTTP method in WebHDFS document.
    (Brahma Reddy Battula via aajisaka)

    HDFS-9431. DistributedFileSystem#concat fails if the target path is
    relative. (Kazuho Fujii via aajisaka)

    HDFS-9434. Recommission a datanode with 500k blocks may pause NN for 30
    seconds for printing info log messags.  (szetszwo)

    HDFS-9470. Encryption zone on root not loaded from fsimage after NN
    restart. (Xiao Chen via wang)

    HDFS-9273. ACLs on root directory may be lost after NN restart.
    (Xiao Chen via cnauroth)

Release 2.6.2 - 2015-10-28

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

  OPTIMIZATIONS

  BUG FIXES

Release 2.6.1 - 2015-09-23

  INCOMPATIBLE CHANGES

  NEW FEATURES

    HDFS-7278. Add a command that allows sysadmins to manually trigger full
    block reports from a DN (cmccabe)

  IMPROVEMENTS

    HDFS-7035. Make adding a new data directory to the DataNode an atomic
    operation and improve error handling (Lei Xu via Colin P. McCabe)

    HDFS-7531. Improve the concurrent access on FsVolumeList (Lei Xu via Colin
    P. McCabe)

    HDFS-7579. Improve log reporting during block report rpc failure.
    (Charles Lamb via cnauroth)

    HDFS-7182. JMX metrics aren't accessible when NN is busy. (Ming Ma via jing9)

    HDFS-7596. NameNode should prune dead storages from storageMap.
    (Arpit Agarwal via cnauroth)

    HDFS-8046. Allow better control of getContentSummary (kihwal)

    HDFS-8384. Allow NN to startup if there are files having a lease but are not
    under construction. (jing9)

  OPTIMIZATIONS

    HDFS-8480. Fix performance and timeout issues in HDFS-7929 by using
    hard-links to preserve old edit logs, instead of copying them. (Zhe Zhang
    via Colin P. McCabe)

  BUG FIXES

    HDFS-7425. NameNode block deletion logging uses incorrect appender.
    (cnauroth)

    HDFS-4882. Prevent the Namenode's LeaseManager from looping forever in
    checkLeases (Ravi Prakash via Colin P. McCabe)

    HDFS-7489. Incorrect locking in FsVolumeList#checkDirs can hang datanodes
    (Noah Lorang via Colin P. McCabe)

    HDFS-7503. Namenode restart after large deletions can cause slow
    processReport. (Arpit Agarwal)

    HDFS-7443. Datanode upgrade to BLOCKID_BASED_LAYOUT fails if duplicate
    block files are present in the same volume (cmccabe)

    HDFS-3443. Fix NPE when namenode transition to active during startup by
    adding checkNNStartup() in NameNodeRpcServer.  (Vinayakumar B via szetszwo)

    HDFS-7733. NFS: readdir/readdirplus return null directory
    attribute on failure. (Arpit Agarwal)

    HDFS-8486. DN startup may cause severe data loss. (daryn via cmccabe)

    HDFS-7213. processIncrementalBlockReport performance degradation.
    (Eric Payne via kihwal)

    HDFS-7314. When the DFSClient lease cannot be renewed, abort open-for-write
    files rather than the entire DFSClient. (mingma)

    HDFS-7235. DataNode#transferBlock should report blocks that don't exist
    using reportBadBlock (yzhang via cmccabe)

    HDFS-7263. Snapshot read can reveal future bytes for appended files.
    (Tao Luo via shv)

    HDFS-7225. Remove stale block invalidation work when DN re-registers with
    different UUID. (Zhe Zhang and Andrew Wang)

    HDFS-7533. Datanode sometimes does not shutdown on receiving upgrade
    shutdown command (Eric Payne via kihwal)

    HDFS-7575. Upgrade should generate a unique storage ID for each
    volume. (Arpit Agarwal)

    HDFS-7707. Edit log corruption due to delayed block removal again.
    (Yongjun Zhang via kihwal)

    HDFS-7714. Simultaneous restart of HA NameNodes and DataNode can cause
    DataNode to register successfully with only one NameNode.(vinayakumarb)

    HDFS-7788. Post-2.6 namenode may not start up with an image containing
    inodes created with an old release. (Rushabh Shah via kihwal)

    HDFS-7009. Active NN and standby NN have different live nodes.
    (Ming Ma via cnauroth)

    HDFS-7763. fix zkfc hung issue due to not catching exception in a corner
    case. (Liang Xie via wang)

    HDFS-7871. NameNodeEditLogRoller can keep printing "Swallowing exception"
    message. (jing9)

    HDFS-7885. Datanode should not trust the generation stamp provided by
    client. (Tsz Wo Nicholas Sze via jing9)

    HDFS-7610. Fix removal of dynamically added DN volumes (Lei (Eddy) Xu via
    Colin P. McCabe)

    HDFS-7830. DataNode does not release the volume lock when adding a volume
    fails. (Lei Xu via Colin P. Mccabe)

    HDFS-7587. Edit log corruption can happen if append fails with a quota
    violation. (jing9)

    HDFS-7929. inotify unable fetch pre-upgrade edit log segments once upgrade
    starts (Zhe Zhang via Colin P. McCabe)

    HDFS-7930. commitBlockSynchronization() does not remove locations. (yliu)

    HDFS-7884. Fix NullPointerException in BlockSender when the generation stamp
    provided by the client is larger than the one stored in the datanode.
    (Brahma Reddy Battula via szetszwo)

    HDFS-7960. The full block report should prune zombie storages even if
    they're not empty. (cmccabe and Eddy Xu via wang)

    HDFS-7742. Favoring decommissioning node for replication can cause a block
    to stay underreplicated for long periods (Nathan Roberts via kihwal)

    HDFS-7999. FsDatasetImpl#createTemporary sometimes holds the FSDatasetImpl
    lock for a very long time (sinago via cmccabe)

    HDFS-8072. Reserved RBW space is not released if client terminates while
    writing block. (Arpit Agarwal)

    HDFS-8127. NameNode Failover during HA upgrade can cause DataNode to
    finalize upgrade. (jing9)

    HDFS-7915. The DataNode can sometimes allocate a ShortCircuitShm slot and
    fail to tell the DFSClient about it because of a network error (cmccabe)

    HDFS-8070. Pre-HDFS-7915 DFSClient cannot use short circuit on
    post-HDFS-7915 DataNode (cmccabe)

    HDFS-8219. setStoragePolicy with folder behavior is different after cluster restart.
    (surendra singh lilhore via Xiaoyu Yao)

    HDFS-7894. Rolling upgrade readiness is not updated in jmx until query
    command is issued. (Brahma Reddy Battula  via kihwal)

    HDFS-8254. Standby namenode doesn't process DELETED_BLOCK if the add block
    request is in edit log. (Rushabh S Shah via kihwal)

    HDFS-8404. Pending block replication can get stuck using older genstamp
    (Nathan Roberts via kihwal)

    HDFS-8431. hdfs crypto class not found in Windows.
    (Anu Engineer via cnauroth)

    HDFS-7609. Avoid retry cache collision when Standby NameNode loading edits.
    (Ming Ma via jing9)

    HDFS-8270. create() always retried with hardcoded timeout when file already
    exists with open lease (J.Andreina via vinayakumarb)

    HDFS-7980. Incremental BlockReport will dramatically slow down namenode
    startup.  (Walter Su via szetszwo)

    HDFS-7446. HDFS inotify should have the ability to determine what txid it
    has read up to (cmccabe)

    HDFS-8846. Add a unit test for INotify functionality across a layout
    version upgrade (Zhe Zhang via Colin P. McCabe)

    HDFS-7470. SecondaryNameNode need twice memory when calling
    reloadFromImageFile. (zhaoyunjiong via cnauroth)

    HDFS-8863. The remaining space check in BlockPlacementPolicyDefault is
    flawed. (Kihwal Lee via yliu)

    HDFS-7552. Change FsVolumeList toString() to fix
    TestDataNodeVolumeFailureToleration (Liang Xie via Colin P. McCabe)

Release 2.6.0 - 2014-11-18

  INCOMPATIBLE CHANGES

  NEW FEATURES

    HDFS-6584. Support archival storage.  (See breakdown of tasks below for
    features and contributors)

    HDFS-6581. Support writing to a single replica in RAM. (See breakdown of
    tasks below for features and contributors).

  IMPROVEMENTS

    HDFS-6613. Improve logging in caching classes. (wang)

    HDFS-6511. BlockManager#computeInvalidateWork() could do nothing. (Juan Yu via wang)

    HDFS-6638. Shorten test run time with a smaller retry timeout setting.
    (Liang Xie via cnauroth)

    HDFS-6627. Rename DataNode#checkWriteAccess to checkReadAccess.
    (Liang Xie via cnauroth)

    HDFS-6645. Add test for successive Snapshots between XAttr modifications.
    (Stephen Chu via jing9)

    HDFS-6643. Refactor INodeWithAdditionalFields.PermissionStatusFormat and
    INodeFile.HeaderFormat. (szetszwo)

    HDFS-6640. Syntax for MKDIRS, CREATESYMLINK, and SETXATTR are given wrongly
    in WebHdfs document (missed webhdfs/v1). (Stephen Chu via jing9)

    HDFS-5202. Support Centralized Cache Management on Windows. (cnauroth)

    HDFS-2976. Remove unnecessary method (tokenRefetchNeeded) in DFSClient.
    (Uma Maheswara Rao G)

    HDFS-3851. DFSOutputStream class code cleanup. (Jing Zhao via suresh)

    HDFS-2856. Fix block protocol so that Datanodes don't require root or jsvc.
    (cnauroth)

    HDFS-5624. Add HDFS tests for ACLs in combination with viewfs.
    (Stephen Chu via cnauroth)

    HDFS-6655. Add 'header banner' to 'explorer.html' also in Namenode UI
    (vinayakumarb)

    HDFS-4120. Add a new "-skipSharedEditsCheck" option for BootstrapStandby
    (Liang Xie and Rakesh R via vinayakumarb)

    HDFS-6597. Add a new option to NN upgrade to terminate the process after
    upgrade on NN is completed. (Danilo Vunjak via cnauroth)

    HDFS-6700. BlockPlacementPolicy shoud choose storage but not datanode for
    deletion. (szetszwo)

    HDFS-6616. Add exclude-datanodes feature to WebHDFS redirection so that it
    will not redirect retries to the same datanode. (zhaoyunjiong via szetszwo)

    HDFS-6702. Change DFSClient to pass the StorageType from the namenode to
    datanodes and change datanode to write block replicas using the specified
    storage type. (szetszwo)

    HDFS-6701. Make seed optional in NetworkTopology#sortByDistance.
    (Ashwin Shankar via wang)

    HDFS-6755. There is an unnecessary sleep in the code path where
    DFSOutputStream#close gives up its attempt to contact the namenode
    (mitdesai21 via cmccabe)

    HDFS-6750. The DataNode should use its shared memory segment to mark
    short-circuit replicas that have been unlinked as stale (cmccabe)

    HDFS-6739. Add getDatanodeStorageReport to ClientProtocol. (szetszwo)

    HDFS-6665. Add tests for XAttrs in combination with viewfs.
    (Stephen Chu via wang)

    HDFS-6778. The extended attributes javadoc should simply refer to the
    user docs. (clamb via wang)

    HDFS-6570. add api that enables checking if a user has certain permissions on
    a file. (Jitendra Pandey via cnauroth)

    HDFS-6441. Add ability to exclude/include specific datanodes while
    balancing. (Benoy Antony and Yu Li via Arpit Agarwal)

    HDFS-6685. Balancer should preserve storage type of replicas.  (szetszwo)

    HDFS-6798. Add test case for incorrect data node condition during
    balancing. (Benoy Antony via Arpit Agarwal)

    HDFS-6796. Improve the argument check during balancer command line parsing.
    (Benoy Antony via szetszwo)

    HDFS-6794. Update BlockManager methods to use DatanodeStorageInfo
    where possible (Arpit Agarwal)

    HDFS-6802. Some tests in TestDFSClientFailover are missing @Test
    annotation. (Akira Ajisaka via wang)

    HDFS-6788. Improve synchronization in BPOfferService with read write lock.
    (Yongjun Zhang via wang)

    HDFS-6787. Remove duplicate code in FSDirectory#unprotectedConcat. (Yi Liu via umamahesh)

    HDFS-6809. Move Balancer's inner classes MovedBlocks and Matcher as to
    standalone classes and separates KeyManager from NameNodeConnector.
    (szetszwo)

    HDFS-6812. Remove addBlock and replaceBlock from DatanodeDescriptor.
    (szetszwo)

    HDFS-6781. Separate HDFS commands from CommandsManual.apt.vm. (Akira
    Ajisaka via Arpit Agarwal)

    HDFS-6728. Dynamically add new volumes to DataStorage, formatted if
    necessary. (Lei Xu vi atm)

    HDFS-6740. Make FSDataset support adding data volumes dynamically. (Lei
    Xu via atm)

    HDFS-6722. Display readable last contact time for dead nodes on NN webUI.
    (Ming Ma via wheat9)

    HDFS-6772. Get DN storages out of blockContentsStale state faster after
    NN restarts. (Ming Ma via Arpit Agarwal)

    HDFS-573. Porting libhdfs to Windows. (cnauroth)

    HDFS-6828. Separate block replica dispatching from Balancer. (szetszwo via
    jing9)

    HDFS-6837. Code cleanup for Balancer and Dispatcher. (szetszwo via
    jing9)

    HDFS-6838. Code cleanup for unnecessary INode replacement.
    (Jing Zhao via wheat9)

    HDFS-6836. HDFS INFO logging is verbose & uses file appenders. (Xiaoyu
    Yao via Arpit Agarwal)

    HDFS-6567. Normalize the order of public final in HdfsFileStatus.
    (Tassapol Athiapinya via wheat9)

    HDFS-6849. Replace HttpFS custom proxyuser handling with common 
    implementation. (tucu)

    HDFS-6850. Move NFS out of order write unit tests into TestWrites class.
    (Zhe Zhang via atm)

    HDFS-6188. An ip whitelist based implementation of TrustedChannelResolver.
    (Benoy Antony via Arpit Agarwal)

    HDFS-6858. Allow dfs.data.transfer.saslproperties.resolver.class default to
    hadoop.security.saslproperties.resolver.class. (Benoy Antony via cnauroth)

    HDFS-6878. Change MiniDFSCluster to support StorageType configuration
    for individual directories. (Arpit Agarwal)

    HDFS-6758. block writer should pass the expected block size to
    DataXceiverServer. (Arpit Agarwal)

    HDFS-6899. Allow changing MiniDFSCluster volumes per DN and capacity
    per volume. (Arpit Agarwal)

    HDFS-4486. Add log category for long-running DFSClient notices (Zhe Zhang
    via Colin Patrick McCabe)

    HDFS-6879. Adding tracing to Hadoop RPC (Masatake Iwasaki via Colin Patrick
    McCabe)

    HDFS-6774. Make FsDataset and DataStore support removing volumes. (Lei Xu
    via atm)

    HDFS-6634. inotify in HDFS. (James Thomas via wang)

    HDFS-4257. The ReplaceDatanodeOnFailure policies could have a forgiving
    option (szetszwo via cmccabe)

    HDFS-6959. Make the HDFS home directory location customizable. (yzhang via
    cmccabe)

    HDFS-6609. Use DirectorySnapshottableFeature to represent a snapshottable
    directory. (Jing Zhao via wheat9)

    HDFS-6886. Use single editlog record for creating file + overwrite. (Yi Liu
    via jing9)

    HDFS-6376. Distcp data between two HA clusters requires another configuration.
    (Dave Marion and Haohui Mai via jing9)

    HDFS-6943. Improve NN allocateBlock log to include replicas' datanode IPs.
    (Ming Ma via wheat9)

    HDFS-6036. Forcibly timeout misbehaving DFSClients that try to do
    no-checksum reads that extend too long (cmccabe)

    HDFS-6482. Use block ID-based block layout on datanodes (James Thomas via
    Colin Patrick McCabe)

    HDFS-7061. Add test to verify encryption zone creation after NameNode
    restart without saving namespace. (Stephen Chu via wang)

    HDFS-7059. HAadmin transtionToActive with forceActive option can show
    confusing message.

    HDFS-6880. Adding tracing to DataNode data transfer protocol. (iwasakims
    via cmccabe)

    HDFS-7006. Test encryption zones with KMS. (Anthony Young-Garner and tucu)

    HDFS-6851. Refactor EncryptionZoneWithId and EncryptionZone. (clamb via wang)

    HDFS-6705. Create an XAttr that disallows the HDFS admin from accessing a
    file. (clamb via wang)

    HDFS-6843. Create FileStatus isEncrypted() method (clamb via cmccabe)

    HDFS-7004. Update KeyProvider instantiation to create by URI. (wang)

    HDFS-7047. Expose FileStatus#isEncrypted in libhdfs (cmccabe)

    HDFS-7003. Add NFS Gateway support for reading and writing to
    encryption zones. (clamb via wang)

    HDFS-6727. Refresh data volumes on DataNode based on configuration changes
    (Lei Xu via cmccabe)

    HDFS-6970. Move startFile EDEK retries to the DFSClient. (wang)

    HDFS-6948. DN rejects blocks if it has older UC block
    (Eric Payne via kihwal)

    HDFS-6987. Move CipherSuite xattr information up to the encryption zone
    root. (Zhe Zhang via wang)

    HDFS-7139. Unit test for creating encryption zone on root path. (Zhe Zhang via wang)

    HDFS-7138. Fix hftp to work with encryption. (clamb via wang)

    HDFS-7118. Improve diagnostics on storage directory rename operations by
    using NativeIO#renameTo in Storage#rename. (cnauroth)

    HDFS-6808. Add command line option to ask DataNode reload configuration.
    (Lei Xu via Colin Patrick McCabe)

    HDFS-7119. Split error checks in AtomicFileOutputStream#close into separate
    conditions to improve diagnostics. (cnauroth)

    HDFS-7077. Separate CipherSuite from crypto protocol version. (wang)

    HDFS-6956. Allow dynamically changing the tracing level in Hadoop servers
    (cmccabe)

    HDFS-7156. Update fsck documentation. (Masahiro Yamaguch via shv)

    HDFS-7093. Add config key to restrict setStoragePolicy. (Arpit Agarwal)

    HDFS-6519. Document oiv_legacy command (Akira AJISAKA via aw)

    HDFS-4165. Faulty sanity check in FsDirectory.unprotectedSetQuota.
    (Binglin Chang via suresh)

    HDFS-7104. Fix and clarify INodeInPath getter functions. (Zhe Zhang via wang)

    HDFS-7124. Remove EncryptionZoneManager.NULL_EZ. (clamb via wang)

    HDFS-6779. Add missing version subcommand for hdfs.
    (Sasaki Toru via wheat9)

    HDFS-7153. Add storagePolicy to NN edit log during file creation.
    (Arpit Agarwal)

    HDFS-7158. Reduce the memory usage of WebImageViewer. (wheat9)

    HDFS-6894. Add XDR parser method for each NFS response.
    (Brandon Li via wheat9)

    HDFS-7169. Add SE_BAD_FIELD to findbugsExcludeFile.xml.  (szetszwo)

    HDFS-7217. Better batching of IBRs. (kihwal)

    HDFS-7195. Update user doc of secure mode about Datanodes don't require root
    or jsvc. (cnauroth)

    HDFS-7228. Add an SSD policy into the default BlockStoragePolicySuite.
    (jing9)

    HDFS-6904. YARN unable to renew delegation token fetched via webhdfs 
    due to incorrect service port. (jitendra)

    HDFS-6988. Improve HDFS-6581 eviction configuration (Xiaoyu Yao via Colin
    P. McCabe)

    HDFS-7230. Add rolling downgrade documentation. (szetszwo via jing9)

    HDFS-6385. Show when block deletion will start after NameNode startup in
    WebUI. (cnauroth)

    HDFS-7313. Support optional configuration of AES cipher suite on
    DataTransferProtocol. (cnauroth)

    HDFS-7276. Limit the number of byte arrays used by DFSOutputStream and
    provide a mechanism for recycling arrays. (szetszwo)

    HDFS-7233. NN logs unnecessary org.apache.hadoop.hdfs.protocol.UnresolvedPathException.
    (Rushabh S Shah via jing9)

    HDFS-7221. TestDNFencingWithReplication fails consistently. (Charles Lamb via wang)

  OPTIMIZATIONS

    HDFS-6690. Deduplicate xattr names in memory. (wang)

    HDFS-6773. MiniDFSCluster should skip edit log fsync by default (Stephen
    Chu via Colin Patrick McCabe)

    HDFS-6865. Byte array native checksumming on client side
    (James Thomas via todd)

    HDFS-7122. Use of ThreadLocal<Random> results in poor block placement.
    (wang)

    HDFS-6606. Optimize HDFS Encrypted Transport performance. (yliu)

  BUG FIXES

    HDFS-7309. XMLUtils.mangleXmlString doesn't seem to handle less than sign
    (Colin Patrick McCabe via raviprak)

    HDFS-6823. dfs.web.authentication.kerberos.principal shows up in logs for 
    insecure HDFS (Allen Wittenauer via raviprak)

    HDFS-6517. Remove hadoop-metrics2.properties from hdfs project (Akira 
    AJISAKA via aw)

    HDFS-6617. Flake TestDFSZKFailoverController.testManualFailoverWithDFSHAAdmin
    due to a long edit log sync op. (Liang Xie via cnauroth)

    HDFS-6646. [ HDFS Rolling Upgrade - Shell ] shutdownDatanode and getDatanodeInfo
    usage is missed ( Brahma Reddy Battula via vinayakumarb)

    HDFS-6630. Unable to fetch the block information by Browsing the file system on
    Namenode UI through IE9 ( Haohui Mai via vinayakumarb)

    HADOOP-8158. Interrupting hadoop fs -put from the command line
    causes a LeaseExpiredException. (daryn via harsh)

    HDFS-6678. MiniDFSCluster may still be partially running after initialization
    fails. (cnauroth)

    HDFS-5809. BlockPoolSliceScanner and high speed hdfs appending make
    datanode to drop into infinite loop (cmccabe)

    HDFS-6456. NFS should throw error for invalid entry in 
    dfs.nfs.exports.allowed.hosts (Abhiraj Butala via brandonli)

    HDFS-6689. NFS doesn't return correct lookup access for direcories (brandonli)

    HDFS-6478. RemoteException can't be retried properly for non-HA scenario.
    (Ming Ma via jing9)

    HDFS-6693. TestDFSAdminWithHA fails on windows ( vinayakumarb )

    HDFS-6667. In HDFS HA mode, Distcp/SLive with webhdfs on secure cluster fails
    with Client cannot authenticate via:[TOKEN, KERBEROS] error. (jing9)

    HDFS-6704. Fix the command to launch JournalNode in HDFS-HA document.
    (Akira AJISAKA via jing9)

    HDFS-6731. Run "hdfs zkfc-formatZK" on a server in a non-namenode will cause
    a null pointer exception. (Masatake Iwasaki via brandonli)

    HDFS-6114. Block Scan log rolling will never happen if blocks written
    continuously leading to huge size of dncp_block_verification.log.curr
    (vinayakumarb via cmccabe)

    HDFS-6455. NFS: Exception should be added in NFS log for invalid separator in
    nfs.exports.allowed.hosts. (Abhiraj Butala via brandonli)

    HDFS-6715. Webhdfs wont fail over when it gets java.io.IOException: Namenode
    is in startup mode. (jing9)

    HDFS-5919. FileJournalManager doesn't purge empty and corrupt inprogress edits
    files (vinayakumarb)

    HDFS-6752. Avoid Address bind errors in TestDatanodeConfig#testMemlockLimit
    (vinayakumarb)

    HDFS-6749. FSNamesystem methods should call resolvePath.
    (Charles Lamb via cnauroth)

    HDFS-4629. Using com.sun.org.apache.xml.internal.serialize.* in
    XmlEditsVisitor.java is JVM vendor specific. Breaks IBM JAVA.
    (Amir Sanjar via stevel)

    HDFS-3482. hdfs balancer throws ArrayIndexOutOfBoundsException 
    if option is specified without values. ( Madhukara Phatak via umamahesh) 

    HDFS-6797. DataNode logs wrong layoutversion during upgrade. (Benoy Antony
    via Arpit Agarwal)

    HDFS-6810. StorageReport array is initialized with wrong size in
    DatanodeDescriptor#getStorageReports. (szetszwo via Arpit Agarwal)

    HDFS-5723. Append failed FINALIZED replica should not be accepted as valid
    when that block is underconstruction (vinayakumarb)

    HDFS-5185. DN fails to startup if one of the data dir is full. (vinayakumarb)

    HDFS-6451. NFS should not return NFS3ERR_IO for AccessControlException 
    (Abhiraj Butala via brandonli)

    HDFS-6717. JIRA HDFS-5804 breaks default nfs-gateway behavior for unsecured config
    (brandonli)

    HDFS-6790. DFSUtil Should Use configuration.getPassword for SSL passwords
    (Larry McCay via brandonli)

    HDFS-6791. A block could remain under replicated if all of its replicas are on
    decommissioned nodes. (Ming Ma via jing9)

    HDFS-6582. Missing null check in RpcProgramNfs3#read(XDR, SecurityHandler)
    (Abhiraj Butala via brandonli)

    HDFS-6830. BlockInfo.addStorage fails when DN changes the storage for a
    block replica (Arpit Agarwal)

    HDFS-6247. Avoid timeouts for replaceBlock() call by sending intermediate
    responses to Balancer (vinayakumarb)

    HDFS-6783. Fix HDFS CacheReplicationMonitor rescan logic. (Yi Liu and Colin Patrick McCabe via umamahesh)

    HDFS-6825. Edit log corruption due to delayed block removal.
    (Yongjun Zhang via wang)

    HDFS-6569. OOB message can't be sent to the client when DataNode shuts down for upgrade
    (brandonli)

    HDFS-6868. portmap and nfs3 are documented as hadoop commands instead of hdfs
    (brandonli)

    HDFS-6870. Blocks and INodes could leak for Rename with overwrite flag. (Yi
    Liu via jing9)

    HDFS-6890. NFS readdirplus doesn't return dotdot attributes (brandonli)

    HDFS-6829. DFSAdmin refreshSuperUserGroupsConfiguration failed in
    security cluster (zhaoyunjiong via Arpit Agarwal)

    HDFS-4852. libhdfs documentation is out of date. (cnauroth)

    HDFS-6908. Incorrect snapshot directory diff generated by snapshot deletion.
    (Juan Yu and jing9 via jing9)

    HDFS-6892. Add XDR packaging method for each NFS request (brandonli)

    HDFS-6902. FileWriter should be closed in finally block in
    BlockReceiver#receiveBlock() (Tsuyoshi OZAWA via Colin Patrick McCabe)

    HDFS-6972. TestRefreshUserMappings.testRefreshSuperUserGroupsConfiguration
    doesn't decode url correctly. (Yongjun Zhang via wang)

    HDFS-6942. Fix typos in log messages. (Ray Chiang via wheat9)

    HDFS-6848. Lack of synchronization on access to datanodeUuid in
    DataStorage#format(). (Xiaoyu Yao via Arpit Agarwal)

    HDFS-6996. SnapshotDiff report can hit IndexOutOfBoundsException when there
    are nested renamed directory/file. (jing9)

    HDFS-6831. Inconsistency between 'hdfs dfsadmin' and 'hdfs dfsadmin -help'.
    (Xiaoyu Yao via Arpit Agarwal)

    HDFS-6979. hdfs.dll does not produce .pdb files. (cnauroth)

    HDFS-6862. Add missing timeout annotations to tests. (Xiaoyu Yao via
    Arpit Agarwal)

    HDFS-6898. DN must reserve space for a full block when an RBW block is
    created. (Arpit Agarwal)

    HDFS-7025. HDFS Credential Provider related Unit Test Failure.
    (Xiaoyu Yao via cnauroth)

    HDFS-7005. DFS input streams do not timeout.

    HDFS-6951. Correctly persist raw namespace xattrs to edit log and fsimage.
    (clamb via wang)

    HDFS-6800. Support Datanode layout changes with rolling upgrade.
    (James Thomas via Arpit Agarwal)

    HDFS-6981. Fix DN upgrade with layout version change. (Arpit Agarwal)

    HDFS-6506. Newly moved block replica been invalidated and deleted in
    TestBalancer. (Binglin Chang via cnauroth)

    HDFS-6966. Add additional unit tests for encryption zones.
    (Stephen Chu via wang)

    HDFS-6621. Hadoop Balancer prematurely exits iterations.
    (Rafal Wojdyla and Benjamin Bowman via wang)

    HDFS-7045. Fix NameNode deadlock when opening file under /.reserved path.
    (Yi Liu via wang)

    HDFS-7032. Add WebHDFS support for reading and writing to encryption zones.
    (clamb via wang)

    HDFS-6965. NN continues to issue block locations for DNs with full disks.
    (Rushabh Shah via kihwal)

    HDFS-6789. TestDFSClientFailover.testFileContextDoesntDnsResolveLogicalURI
    and TestDFSClientFailover.testDoesntDnsResolveLogicalURI failing on jdk7.
    (Akira Ajisaka via wang)

    HDFS-6912. SharedFileDescriptorFactory should not allocate sparse files
    (cmccabe)

    HDFS-7075. hadoop-fuse-dfs fails because it cannot find
    JavaKeyStoreProvider$Factory (cmccabe)

    HDFS-7078. Fix listEZs to work correctly with snapshots. (wang)

    HDFS-6840. Clients are always sent to the same datanode when read
    is off rack. (wang)

    HDFS-7065. Pipeline close recovery race can cause block corruption (kihwal)

    HDFS-7096. Fix TestRpcProgramNfs3 to use DFS_ENCRYPTION_KEY_PROVIDER_URI
    (clamb via cmccabe)

    HDFS-7046. HA NN can NPE upon transition to active. (kihwal)

    HDFS-7106. Reconfiguring DataNode volumes does not release the lock files
    in removed volumes. (cnauroth via cmccabe)

    HDFS-7001. Tests in TestTracing depends on the order of execution
    (iwasakims via cmccabe)

    HDFS-7132. hdfs namenode -metadataVersion command does not honor
    configured name dirs. (Charles Lamb via wang)

    HDFS-7049. TestByteRangeInputStream.testPropagatedClose fails and throw
    NPE on branch-2. (Juan Yu via wheat9)

    HDFS-7148. TestEncryptionZones#testIsEncryptedMethod fails on branch-2
    after archival storage merge. (wang)

    HDFS-7157. Using Time.now() for recording start/end time of reconfiguration
    tasks (Lei Xu via cmccabe)

    HDFS-6664. HDFS permissions guide documentation states incorrect default
    group mapping class. (Ray Chiang via aw)

    HDFS-4227. Document dfs.namenode.resource.*  (Daisuke Kobayashi via aw)

    HDFS-6754. TestNamenodeCapacityReport may sometimes fail due to lack of
    retry. (Mit Desai via kihwal)

    HDFS-7172. Test data files may be checked out of git with incorrect line
    endings, causing test failures in TestHDFSCLI. (Chris Nauroth via wheat9)

    HDFS-7176. The namenode usage message doesn't include "-rollingupgrade
    started" (cmccabe)

    HDFS-7178. Additional unit test for replica write with full disk.
    (Arpit Agarwal)

    HDFS-7162. Wrong path when deleting through fuse-dfs a file which already
    exists in trash (Chengbing Liu via cmccabe)

    HDFS-7179. DFSClient should instantiate a KeyProvider, not a
    KeyProviderCryptoExtension. (wang)

    HDFS-7181. Remove incorrect precondition check on key length in
    FileEncryptionInfo. (wang)

    HDFS-7203. Concurrent appending to the same file can cause data corruption
    (kihwal)

    HDFS-7236. Fix TestOpenFilesWithSnapshot#testOpenFilesWithMultipleSnapshots.
    (Yongjun Zhang via jing9)

    HDFS-6544. Broken Link for GFS in package.html. (Suraj Nayak M via wheat9)

    HDFS-7237. The command "hdfs namenode -rollingUpgrade" throws
    ArrayIndexOutOfBoundsException.  (szetszwo)

    HDFS-7185. The active NameNode will not accept an fsimage sent from the
    standby during rolling upgrade. (jing9)

    HDFS-7208. NN doesn't schedule replication when a DN storage fails.
    (Ming Ma via szetszwo)

    HDFS-5089. When a LayoutVersion support SNAPSHOT, it must support
    FSIMAGE_NAME_OPTIMIZATION.  (szetszwo)

    HDFS-7260. Change DFSOutputStream.MAX_PACKETS to be configurable. (szetszwo)

    HDFS-7259. Unresponseive NFS mount point due to deferred COMMIT response.
    (brandonli)

    HDFS-7215.Add JvmPauseMonitor to NFS gateway (brandonli)

    HDFS-7180. NFSv3 gateway frequently gets stuck due to GC (brandonli)

    HDFS-7243. HDFS concat operation should not be allowed in Encryption Zone.
    (clamb via yliu)

    HADOOP-11233. hadoop.security.kms.client.encrypted.key.cache.expiry
    property spelled wrong in core-default. (Stephen Chu via yliu)

    HDFS-7218. FSNamesystem ACL operations should write to audit log on
    failure. (clamb via yliu)

    HDFS-7199. DFSOutputStream should not silently drop data if DataStreamer
    crashes with an unchecked exception (rushabhs via cmccabe)

    HDFS-7383. DataNode.requestShortCircuitFdsForRead may throw
    NullPointerException. (szetszwo via suresh)

    HDFS-7147. Update archival storage user documentation.
    (Tsz Wo Nicholas Sze via wheat9)

    HDFS-7340. Make rollingUpgrade start/finalize idempotent. (jing9)

    HDFS-7334. Fix periodic failures of TestCheckpoint
    #testTooManyEditReplayFailures. (Charles Lamb via wheat9)

    HDFS-7355. TestDataNodeVolumeFailure#testUnderReplicationAfterVolFailure
    fails on Windows, because we cannot deny access to the file owner.
    (Chris Nauroth via wheat9)

    HDFS-7367. HDFS short-circuit read cannot negotiate shared memory slot and
    file descriptors when SASL is enabled on DataTransferProtocol.
    (Chris Nauroth via wheat9)

    HDFS-7364. Balancer always shows zero Bytes Already Moved.
    (Tsz Wo Nicholas Sze via jing9)

    HDFS-7379. TestBalancer#testBalancerWithRamDisk creates test files
    incorrectly. (Xiaoyu Yao via wheat9)

    BREAKDOWN OF HDFS-6134 AND HADOOP-10150 SUBTASKS AND RELATED JIRAS
  
      HDFS-6387. HDFS CLI admin tool for creating & deleting an
      encryption zone. (clamb)
  
      HDFS-6386. HDFS Encryption Zones (clamb)
  
      HDFS-6388. HDFS integration with KeyProvider. (clamb)
  
      HDFS-6473. Protocol and API for Encryption Zones (clamb)
  
      HDFS-6392. Wire crypto streams for encrypted files in
      DFSClient. (clamb and yliu)
  
      HDFS-6476. Print out the KeyProvider after finding KP successfully on
      startup. (Juan Yu via wang)
  
      HDFS-6391. Get the Key/IV from the NameNode for encrypted files in
      DFSClient. (Charles Lamb and wang)
  
      HDFS-6389. Rename restrictions for encryption zones. (clamb)
  
      HDFS-6605. Client server negotiation of cipher suite. (wang)
  
      HDFS-6625. Remove the Delete Encryption Zone function (clamb)
  
      HDFS-6516. List of Encryption Zones should be based on inodes (clamb)
  
      HDFS-6629. Not able to create symlinks after HDFS-6516 (umamaheswararao)
  
      HDFS-6635. Refactor encryption zone functionality into new
      EncryptionZoneManager class. (wang)
  
      HDFS-6474. Namenode needs to get the actual keys and iv from the
      KeyProvider. (wang)
  
      HDFS-6619. Clean up encryption-related tests. (wang)
  
      HDFS-6405. Test Crypto streams in HDFS. (yliu via wang)
  
      HDFS-6490. Fix the keyid format for generated keys in
      FSNamesystem.createEncryptionZone (clamb)
  
      HDFS-6716. Update usage of KeyProviderCryptoExtension APIs on NameNode.
      (wang)
  
      HDFS-6718. Remove EncryptionZoneManager lock. (wang)
  
      HDFS-6720. Remove KeyProvider in EncryptionZoneManager. (wang)
  
      HDFS-6738. Remove unnecessary getEncryptionZoneForPath call in
      EZManager#createEncryptionZone. (clamb)
  
      HDFS-6724. Decrypt EDEK before creating
      CryptoInputStream/CryptoOutputStream. (wang)
  
      HDFS-6509. Create a special /.reserved/raw directory for raw access to
      encrypted data. (clamb via wang)
  
      HDFS-6771. Require specification of an encryption key when creating
      an encryption zone. (wang)
  
      HDFS-6730. Create a .RAW extended attribute namespace. (clamb)
  
      HDFS-6692. Add more HDFS encryption tests. (wang)
  
      HDFS-6780. Batch the encryption zones listing API. (wang)
  
      HDFS-6394. HDFS encryption documentation. (wang)
  
      HDFS-6834. Improve the configuration guidance in DFSClient when there 
      are no Codec classes found in configs. (umamahesh)
  
      HDFS-6546. Add non-superuser capability to get the encryption zone
      for a specific path. (clamb)
  
      HDFS-6733. Creating encryption zone results in NPE when
      KeyProvider is null. (clamb)
  
      HDFS-6785. Should not be able to create encryption zone using path
      to a non-directory file. (clamb)
  
      HDFS-6807. Fix TestReservedRawPaths. (clamb)
  
      HDFS-6814. Mistakenly dfs.namenode.list.encryption.zones.num.responses configured
      as boolean. (umamahesh)
  
      HDFS-6817. Fix findbugs and other warnings. (yliu)
  
      HDFS-6839. Fix TestCLI to expect new output. (clamb)

      HDFS-6954. With crypto, no native lib systems are too verbose. (clamb via wang)

      HDFS-2975. Rename with overwrite flag true can make NameNode to stuck in safemode 
      on NN (crash + restart). (Yi Liu via umamahesh)

      HDFS-6905. fs-encryption merge triggered release audit failures. (clamb via tucu)

      HDFS-6714. TestBlocksScheduledCounter#testBlocksScheduledCounter should
      shutdown cluster (vinayakumarb)

      HDFS-6986. DistributedFileSystem must get delegation tokens from configured 
      KeyProvider. (zhz via tucu)

    HDFS-6776. Using distcp to copy data between insecure and secure cluster via webdhfs 
    doesn't work. (yzhangal via tucu)

    HDFS-7042. Upgrade fails for Windows HA cluster due to file locks held during
    rename in JournalNode. (cnauroth)

    HDFS-7051. TestDataNodeRollingUpgrade#isBlockFileInPrevious assumes Unix file
    path separator. (cnauroth)

    HDFS-7105. Fix TestJournalNode#testFailToStartWithBadConfig to match log
    output change. (Ray Chiang via cnauroth)

    HDFS-7105. Allow falling back to a non-SASL connection on
    DataTransferProtocol in several edge cases. (cnauroth)

    HDFS-7107. Avoid Findbugs warning for synchronization on
    AbstractNNFailoverProxyProvider#fallbackToSimpleAuth. (cnauroth)

    HDFS-7109. TestDataStorage does not release file locks between tests.
    (cnauroth)

    HDFS-7110. Skip tests related to short-circuit read on platforms that do not
    currently implement short-circuit read. (cnauroth)

    HDFS-7115. TestEncryptionZones assumes Unix path separator for KMS key store
    path. (Xiaoyu Yao via cnauroth)

    HDFS-7115. TestEncryptionZonesWithHA assumes Unix path separator for KMS key
    store path. (Xiaoyu Yao via cnauroth)

    HDFS-7130. TestDataTransferKeepalive fails intermittently on Windows.
    (cnauroth)

    HDFS-6534. Fix build on macosx: HDFS parts (Binglin Chang via aw)

    HDFS-7111. TestSafeMode assumes Unix line endings in safe mode tip.
    (cnauroth)

    HDFS-7127. TestLeaseRecovery leaks MiniDFSCluster instances. (cnauroth)

    HDFS-7131. During HA upgrade, JournalNode should create a new committedTxnId
    file in the current directory. (jing9)

    HDFS-6995. Block should be placed in the client's 'rack-local' node
    if 'client-local' node is not available (vinayakumarb)

    HDFS-7128. Decommission slows way down when it gets towards the end.
    (Ming Ma via cnauroth)

    HDFS-7287. The OfflineImageViewer (OIV) can output invalid XML depending on
    the filename (Ravi Prakash via Colin P. McCabe)

    HDFS-7300. The getMaxNodesPerRack() method in BlockPlacementPolicyDefault
    is flawed (kihwal)

    HDFS-7305. NPE seen in wbhdfs FS while running SLive. (jing9)

  BREAKDOWN OF HDFS-6584 ARCHIVAL STORAGE

    HDFS-6677. Change INodeFile and FSImage to support storage policy ID.
    (szetszwo)

    HDFS-6670. Add block storage policy support with default HOT, WARM and COLD
    policies.  (szetszwo)

    HDFS-6671. Change BlockPlacementPolicy to consider block storage policy
    in replicaiton.  (szetszwo)

    HDFS-6710. Change BlockPlacementPolicy to consider block storage policy
    in replica deletion.  (szetszwo)

    HDFS-6679. Bump NameNodeLayoutVersion and update editsStored test files.
    (vinayakumarb via szetszwo)

    HDFS-6686. Change BlockPlacementPolicy to use fallback when some storage
    types are unavailable.  (szetszwo)

    HDFS-6835. Add a new API to set storage policy.  (jing9) 

    HDFS-6847. Support storage policy on directories and include storage policy 
    in HdfsFileStatus.  (Jing Zhao via szetszwo)

    HDFS-6801. Add a new data migration tool, Mover, for archiving data.
    (szetszwo via jing9)

    HDFS-6863. Support migration for snapshot paths. (jing9)

    HDFS-6906. Add more tests for BlockStoragePolicy.  (szetszwo via jing9)

    HDFS-6911. check if a block is already scheduled in Mover. 
    (szetszwo via jing9)

    HDFS-6920. Check the storage type of delNodeHintStorage when deleting
    a replica.  (szetszwo via jing9)

    HDFS-6944. Add retry and termination logic for Mover. (jing9)

    HDFS-6969. INode#getStoragePolicyID should always return the latest
    storage policy.  (jing9)

    HDFS-6961. BlockPlacementPolicy#chooseTarget should check each valid
    storage type in each choosing round.  (jing9)

    HDFS-6876. support set/get storage policy in DFSAdmin. (jing9)

    HDFS-6997. Add more tests for data migration and replicaion. (szetszwo)

    HDFS-6875. Support migration for a list of specified paths. (jing9)

    HDFS-7027. Mover does not terminate when some storage type is out of space.
    (szetszwo via jing9)

    HDFS-7029. Fix TestDFSInotifyEventInputStream and TestDistributedFileSystem.
    (szetszwo via jing9)

    HDFS-7028. FSDirectory should not get storage policy id from symlinks.
    (szetszwo)

    HDFS-7034. Fix TestBlockPlacement and TestStorageMover. (jing9)

    HDFS-7039. Fix Balancer tests.  (szetszwo via jing9)

    HDFS-7062. Skip under construction block for migration. (jing9)

    HDFS-7052. Add Mover into hdfs script. (jing9)

    HDFS-7072. Fix TestBlockManager and TestStorageMover.  (jing9 via szetszwo)

    HDFS-6864. Archival Storage: add user documentation. (szetszwo via jing9)

    HDFS-7088. Archival Storage: fix TestBalancer and
    TestBalancerWithMultipleNameNodes. (szetszwo via jing9)

    HDFS-7095. TestStorageMover often fails in Jenkins. (jing9)

    HDFS-7081. Add new DistributedFileSystem API for getting all the existing
    storage policies. (jing9)

    HDFS-7140. Add a tool to list all the existing block storage policies.
    (jing9)

    HDFS-7167. NPE while running Mover if the given path is for a file. (jing9)

    HDFS-7154. Fix returning value of starting reconfiguration task (Lei Xu via
    Colin P. McCabe)

  BREAKDOWN OF HDFS-6581 SUBTASKS AND RELATED JIRAS

    HDFS-6921. Add LazyPersist flag to FileStatus. (Arpit Agarwal)

    HDFS-6924. Add new RAM_DISK storage type. (Arpit Agarwal)

    HDFS-6922. Add LazyPersist flag to INodeFile, save it in FsImage and
    edit logs. (Arpit Agarwal)

    HDFS-6923. Propagate LazyPersist flag to DNs via DataTransferProtocol.
    (Arpit Agarwal)

    HDFS-6925. DataNode should attempt to place replicas on transient storage
    first if lazyPersist flag is received. (Arpit Agarwal)

    HDFS-6926. DN support for saving replicas to persistent storage and
    evicting in-memory replicas. (Arpit Agarwal)

    HDFS-6927. Initial unit tests for lazy persist files. (Arpit Agarwal)

    HDFS-6929. NN periodically unlinks lazy persist files with missing
    replicas from namespace. (Arpit Agarwal)

    HDFS-6928. 'hdfs put' command should accept lazyPersist flag for testing.
    (Arpit Agarwal)

    HDFS-6960. Bugfix in LazyWriter, fix test case and some refactoring.
    (Arpit Agarwal)

    HDFS-6931. Move lazily persisted replicas to finalized directory on DN
    startup. (Arpit Agarwal)

    HDFS-6950. Add Additional unit tests for HDFS-6581. (Xiaoyu Yao via
    Arpit Agarwal)

    HDFS-6930. Improve replica eviction from RAM disk. (Arpit Agarwal)

    HDFS-6977. Delete all copies when a block is deleted from the block space.
    (Arpit Agarwal)

    HDFS-6991. Notify NN of evicted block before deleting it from RAM disk.
    (Arpit Agarwal)

    HDFS-6978. Directory scanner should correctly reconcile blocks on RAM
    disk. (Arpit Agarwal)

    HDFS-7066. LazyWriter#evictBlocks misses a null check for replicaState.
    (Xiaoyu Yao via Arpit Agarwal)

    HDFS-7064. Fix unit test failures in HDFS-6581 branch. (Xiaoyu Yao via
    Arpit Agarwal)

    HDFS-6581. Few more unit test fixes for HDFS-6581. (Arpit Agarwal)

    HDFS-7080. Fix finalize and upgrade unit test failures. (Arpit Agarwal)

    HDFS-7084. FsDatasetImpl#copyBlockFiles debug log can be improved.
    (Xiaoyu Yao via Arpit Agarwal)

    HDFS-7091. Add forwarding constructor for INodeFile for existing callers.
    (Arpit Agarwal)

    HDFS-7100. Make eviction scheme pluggable. (Arpit Agarwal)

    HDFS-7108. Fix unit test failures in SimulatedFsDataset. (Arpit Agarwal)

    HDFS-7071. Updated editsStored and editsStored.xml to bump layout
    version and add LazyPersist flag. (Xiaoyu Yao and Arpit Agarwal via
    Arpit Agarwal)

    HDFS-6990. Add unit test for evict/delete RAM_DISK block with open
    handle. (Xiaoyu Yao via Arpit Agarwal)

    HDFS-7143. Fix findbugs warnings in HDFS-6581 branch. (szetszwo via
    Arpit Agarwal)

    HDFS-6932. Balancer and Mover tools should ignore replicas on RAM_DISK.
    (Xiaoyu Yao via Arpit Agarwal)

    HDFS-7144. Fix findbugs warnings in RamDiskReplicaTracker. (szetszwo via
    Arpit Agarwal)

    HDFS-7155. Bugfix in createLocatedFileStatus caused by bad merge.
    (Arpit Agarwal)

    HDFS-7153. Add storagePolicy to NN edit log during file creation.
    (Arpit Agarwal)

    HDFS-7159. Use block storage policy to set lazy persist preference.
    (Arpit Agarwal)

    HDFS-7129. Metrics to track usage of memory for writes. (Xiaoyu Yao
    via Arpit Agarwal)

    HDFS-7171. Fix Jenkins failures in HDFS-6581 branch. (Arpit Agarwal)

    HDFS-7112. LazyWriter should use either async IO or one thread per physical
    disk. (Xiaoyu Yao via cnauroth)

    HDFS-7090. Use unbuffered writes when persisting in-memory replicas.
    (Xiaoyu Yao via cnauroth)

    HDFS-6934. Move checksum computation off the hot path when writing to RAM
    disk. (cnauroth)

    HDFS-7291. Persist in-memory replicas with appropriate unbuffered copy API
    on POSIX and Windows. (Xiaoyu Yao via cnauroth)

    HDFS-7328. TestTraceAdmin assumes Unix line endings. (cnauroth)

    HDFS-7359. NameNode in secured HA cluster fails to start if
    dfs.namenode.secondary.http-address cannot be interpreted as a network
    address. (cnauroth)

    HDFS-7226. Fix TestDNFencing.testQueueingWithAppend. (Yongjun Zhang via jing9)

    HDFS-7382. DataNode in secure mode may throw NullPointerException if client
    connects before DataNode registers itself with NameNode. (cnauroth)

    HDFS-7387. NFS may only do partial commit due to a race between COMMIT and write
    (brandonli)

    HDFS-7391. Renable SSLv2Hello in HttpFS. (rkanter via acmurthy)

    HDFS-7385. ThreadLocal used in FSEditLog class causes FSImage permission mess
    up. (jiangyu via cnauroth)

Release 2.5.2 - 2014-11-19

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

  OPTIMIZATIONS

  BUG FIXES

    HDFS-7274. Disable SSLv3 in HttpFS. (Robert Kanter via kasha)

Release 2.5.1 - 2014-09-05

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

  OPTIMIZATIONS

  BUG FIXES

    HADOOP-10957. The globber will sometimes erroneously return a permission
    denied exception when there is a non-terminal wildcard (cmccabe)

Release 2.5.0 - 2014-08-11

  INCOMPATIBLE CHANGES

    HDFS-6168. Remove a deprecated constructor and the deprecated methods reportChecksumFailure,
    getDelegationToken(Text), renewDelegationToken and cancelDelegationToken from
    DistributedFileSystem.  (szetszwo)

  NEW FEATURES

    HDFS-6281. Provide option to use the NFS Gateway without having to use the
    Hadoop portmapper. (atm)

    HDFS-5168. Add cross node dependency support to BlockPlacementPolicy.
    (Nikola Vujic via szetszwo)

    HDFS-6334. Client failover proxy provider for IP failover based NN HA.
    (kihwal)

    HDFS-6406. Add capability for NFS gateway to reject connections from
    unprivileged ports. (atm)

    HDFS-2006. Ability to support storing extended attributes per file.

    HDFS-5978. Create a tool to take fsimage and expose read-only WebHDFS API.
    (Akira Ajisaka via wheat9)

    HDFS-6278. Create HTML5-based UI for SNN. (wheat9)

    HDFS-6279. Create new index page for JN / DN. (wheat9)

  IMPROVEMENTS

    HDFS-6007. Update documentation about short-circuit local reads (iwasakims
    via cmccabe)

    HDFS-6125. Cleanup unnecessary cast in HDFS code base. (suresh)

    HDFS-5196. Provide more snapshot information in WebUI.
    (Shinichi Yamashita via wheat9)

    HDFS-6155. Fix Boxing/unboxing to parse a primitive findbugs warnings.
    (suresh)

    HDFS-6119. FSNamesystem code cleanup. (suresh)

    HDFS-6158. Clean up dead code for OfflineImageViewer. (wheat9)

    HDFS-6164. Remove lsr in OfflineImageViewer. (wheat9)

    HDFS-6167. Relocate the non-public API classes in the hdfs.client package.
    (szetszwo)

    HDFS-6191. Disable quota checks when replaying edit log. (kihwal)

    HDFS-6170. Support GETFILESTATUS operation in WebImageViewer.
    (Akira Ajisaka via wheat9)

    HDFS-6225. Remove the o.a.h.hdfs.server.common.UpgradeStatusReport.
    (wheat9)
    
    HDFS-6224. Add a unit test to TestAuditLogger for file permissions
    passed to logAuditEvent. (Charles Lamb via wang)

    HDFS-6194. Create new tests for ByteRangeInputStream.
    (Akira Ajisaka via wheat9)

    HDFS-6219. Proxy superuser configuration should use true client IP for
    address checks. (daryn via kihwal)

    HDFS-6256. Clean up ImageVisitor and SpotCheckImageVisitor.
    (Akira Ajisaka via wheat9)

    HDFS-6265. Prepare HDFS codebase for JUnit 4.11. (cnauroth)

    HDFS-5693. Few NN metrics data points were collected via JMX when NN
    is under heavy load. (Ming Ma via jing9)

    HDFS-6273. Config options to allow wildcard endpoints for namenode HTTP
    and HTTPS servers. (Arpit Agarwal)

    HDFS-6282. Re-add testIncludeByRegistrationName. (cmccabe)

    HDFS-6266. Identify full path for a given INode. (jing9)

    HDFS-6210. Support GETACLSTATUS operation in WebImageViewer.
    (Akira Ajisaka via wheat9)

    HDFS-6269. NameNode Audit Log should differentiate between webHDFS open and
    HDFS open. (Eric Payne via jeagles)

    HDFS-6304. Consolidate the logic of path resolution in FSDirectory.
    (wheat9)

    HDFS-6295. Add "decommissioning" state and node state filtering to
    dfsadmin. (wang)

    HDFS-6294. Use INode IDs to avoid conflicts when a file open for write is
    renamed. (cmccabe)

    HDFS-6328. Clean up dead code in FSDirectory. (wheat9)

    HDFS-6230. Expose upgrade status through NameNode web UI.
    (Mit Desai via wheat9)

    HDFS-6186. Pause deletion of blocks when the namenode starts up. (jing9)

    HDFS-6293. Issues with OIV processing PB-based fsimages. (kihwal)

    HDFS-2949. Add check to active state transition to prevent operator-induced
    split brain. (Rushabh S Shah via kihwal)

    HDFS-6287. Add vecsum test of libhdfs read access times (cmccabe)

    HDFS-5683. Better audit log messages for caching operations.
    (Abhiraj Butala via wang)

    HDFS-6345. DFS.listCacheDirectives() should allow filtering based on
    cache directive ID. (wang)

    HDFS-6432. Add snapshot related APIs to webhdfs. (jing9)

    HDFS-6396. Remove support for ACL feature from INodeSymlink.
    (Charles Lamb via wang)

    HDFS-6435. Add support for specifying a static uid/gid mapping for the NFS
    gateway. (atm via wang)

    HDFS-6110 adding more slow action log in critical write path
    (Liang Xie via stack)

    HDFS-6416. Use Time#monotonicNow in OpenFileCtx and OpenFileCtxCatch to
    avoid system clock bugs (Abhiraj Butala via brandonli)

    HDFS-6356. Fix typo in DatanodeLayoutVersion. (Tulasi G via wang)

    HDFS-6447. balancer should timestamp the completion message.
    (Juan Yu via wang)

    HDFS-6463. Clarify behavior of AclStorage#createFsPermissionForExtendedAcl
    in comments. (cnauroth)

    HDFS-6472. fix typo in webapps/hdfs/explorer.js. (Juan Yu via wang)

    HDFS-6056. Clean up NFS config settings (brandonli)

    HDFS-6109 let sync_file_range() system call run in background
    (Liang Xie via stack)

    HDFS-6268. Better sorting in NetworkTopology#pseudoSortByDistance when
    no local node is found. (wang)

    HDFS-6369. Document that BlockReader#available() can return more bytes than
    are remaining in the block (Ted Yu via Colin Patrick McCabe)

    HDFS-6487. TestStandbyCheckpoint#testSBNCheckpoints is racy.
    (Mit Desai via wang)

    HDFS-6297. Add CLI testcases to reflect new features of dfs and dfsadmin
    (Dasha Boudnik via cos)

    HDFS-6399. Add note about setfacl in HDFS permissions guide.
    (cnauroth via wang)

    HDFS-6315. Decouple recording edit logs from FSDirectory. (wheat9)

    HDFS-6379. HTTPFS - Implement ACLs support. (yoderme via tucu)

    HDFS-6471. Make moveFromLocal CLI testcases to be non-disruptive
    (Dasha Boudnik via cos)

    HDFS-6395. Skip checking xattr limits for non-user-visible namespaces.
    (Yi Liu via wang).

    HDFS-3493. Invalidate excess corrupted blocks as long as minimum
    replication is satisfied. (Juan Yu and Vinayakumar B via wang)

    HDFS-6330. Move mkdirs() to FSNamesystem. (wheat9)

    HDFS-6470. TestBPOfferService.testBPInitErrorHandling is flaky.
    (Ming Ma via wang)

    HDFS-6529. Trace logging for RemoteBlockReader2 to identify remote datanode
    and file being read. (Anubhav Dhoot via atm)

    HDFS-6499. Use NativeIO#renameTo instead of File#renameTo in
    FileJournalManager. (Yongjun Zhang via atm)

    HDFS-6518. TestCacheDirectives#testExceedsCapacity should
    take FSN read lock when accessing pendingCached list.
    (wang)

    HDFS-6528. Add XAttrs to TestOfflineImageViewer. (Stephen Chu via wang)

    HDFS-6545. Finalizing rolling upgrade can make NN unavailable for a long
    duration. (kihwal)

    HDFS-6530. Fix Balancer documentation.  (szetszwo)

    HDFS-6480. Move waitForReady() from FSDirectory to FSNamesystem. (wheat9)

    HDFS-6403. Add metrics for log warnings reported by JVM pauses. (Yongjun
    Zhang via atm)

    HDFS-6557. Move the reference of fsimage to FSNamesystem. (wheat9)

    HDFS-4667. Capture renamed files/directories in snapshot diff report. (jing9
    and Binglin Chang via jing9)

    HDFS-6507. Improve DFSAdmin to support HA cluster better.
    (Zesheng Wu via vinayakumarb)

    HDFS-6578. add toString method to DatanodeStorage for easier debugging.
    (Yongjun Zhang via Arpit Agarwal)

    HDFS-6562. Refactor rename() in FSDirectory. (wheat9)

    HDFS-6486. Add user doc for XAttrs via WebHDFS. (Yi Liu via umamahesh)

    HDFS-6430. HTTPFS - Implement XAttr support. (Yi Liu via tucu)

    HDFS-6593. Move SnapshotDiffInfo out of INodeDirectorySnapshottable.
    (Jing Zhao via wheat9)

    HDFS-6595. Allow the maximum threads for balancing on datanodes to be
    configurable. (Benoy Antony via szetszwo)

    HDFS-6572. Add an option to the NameNode that prints the software and
    on-disk image versions. (Charles Lamb via cnauroth)

    HDFS-6603. Add XAttr with ACL test. (Stephen Chu via cnauroth)

    HDFS-6612. MiniDFSNNTopology#simpleFederatedTopology(int)
    always hardcode nameservice ID. (Juan Yu via wang)

    HDFS-6614. shorten TestPread run time with a smaller retry timeout setting.
    (Liang Xie via cnauroth)

    HDFS-6610. TestShortCircuitLocalRead tests sometimes timeout on slow
    machines. (Charles Lamb via wang)

    HDFS-6620. Snapshot docs should specify about preserve options with cp command
    (Stephen Chu via umamahesh)

    HDFS-6493. Change dfs.namenode.startup.delay.block.deletion to second
    instead of millisecond. (Juan Yu via wang)

    HDFS-6680. BlockPlacementPolicyDefault does not choose favored nodes
    correctly.  (szetszwo) 

    HDFS-6712. Document HDFS Multihoming Settings. (Arpit Agarwal)

  OPTIMIZATIONS

    HDFS-6214. Webhdfs has poor throughput for files >2GB (daryn)

    HDFS-6460. Ignore stale and decommissioned nodes in
    NetworkTopology#sortByDistance. (Yongjun Zhang via wang)

    HDFS-6583. Remove clientNode in FileUnderConstructionFeature. (wheat9)

    HDFS-6599. 2.4 addBlock is 10 to 20 times slower compared to 0.23 (daryn)

  BUG FIXES 

    HDFS-6112. NFS Gateway docs are incorrect for allowed hosts configuration.
    (atm)

    HDFS-3087. Decomissioning on NN restart can complete without blocks being
    replicated. (Rushabh S Shah via kihwal)

    HDFS-6162. Format strings should use platform independent line separator.
    (suresh)

    HDFS-6156. Simplify the JMX API that provides snapshot information.
    (wheat9)

    HDFS-6173. Move the default processor from Ls to Web in OfflineImageViewer.
    (Akira Ajisaka via wheat9)

    HDFS-5591. Checkpointing should use monotonic time when calculating period.
    (Charles Lamb via wang)

    HDFS-6190. Minor textual fixes in DFSClient. (Charles Lamb via wheat9)

    HDFS-6159. TestBalancerWithNodeGroup.testBalancerWithNodeGroup fails if 
    there is block missing after balancer success (Chen He via kihwal)

    HDFS-6181. Fix the wrong property names in NFS user guide (brandonli)

    HDFS-6180. dead node count / listing is very broken in JMX and old GUI.
    (wheat9)

    HDFS-6143. WebHdfsFileSystem open should throw FileNotFoundException for
    non-existing paths. (Gera Shegalov via wheat9)

    HDFS-6169. Move the address in WebImageViewer. (Akira Ajisaka via wheat9)

    HDFS-6160. TestSafeMode occasionally fails. (Arpit Agarwal)

    HDFS-5669. Storage#tryLock() should check for null before logging successfull message
    (Vinayakumar B via umamahesh)

    HDFS-6237. TestDFSShell#testGet fails on Windows due to invalid file system
    path. (cnauroth)

    HDFS-6238. TestDirectoryScanner leaks file descriptors. (cnauroth)

    HDFS-6243. HA NameNode transition to active or shutdown may leave lingering
    image transfer thread. (cnauroth)

    HDFS-5409. TestOfflineEditsViewer#testStored fails on Windows due to CRLF
    line endings in editsStored.xml from git checkout. (cnauroth)

    HDFS-4909. Avoid protocol buffer RPC namespace clashes. (cmccabe)

    HDFS-6178. Decommission on standby NN couldn't finish. (Ming Ma via jing9)

    HDFS-6213. TestDataNodeConfig failing on Jenkins runs due to DN web port
    in use. (wang)

    HDFS-6274. Cleanup javadoc warnings in HDFS code. (suresh)

    HDFS-6275. Fix warnings - type arguments can be inferred and redudant
    local variable. (suresh)

    HDFS-6217. Webhdfs PUT operations may not work via a http proxy.
    (Daryn Sharp via kihwal)

    HDFS-6276. Remove unnecessary conditions and null check. (suresh)

    HDFS-5865. Update OfflineImageViewer document. (Akira Ajisaka via wheat9)

    HDFS-6270. Secondary namenode status page shows transaction count in bytes.
    (Benoy Antony via wheat9)

    HDFS-6218. Audit log should use true client IP for proxied webhdfs
    operations. (daryn via kihwal)

    HDFS-6288. DFSInputStream Pread doesn't update ReadStatistics.
    (Juan Yu via wang)

    HDFS-5892. TestDeleteBlockPool fails in branch-2. (Ted Yu via wheat9)

    HDFS-6289. HA failover can fail if there are pending DN messages for DNs
    which no longer exist. (atm)

    HDFS-6337. Setfacl testcase is failing due to dash character in username
    in TestAclCLI (umamahesh)

    HDFS-5381. ExtendedBlock#hashCode should use both blockId and block pool ID
    (Benoy Antony via Colin Patrick McCabe)

    HDFS-6240. WebImageViewer returns 404 if LISTSTATUS to an empty directory.
    (Akira Ajisaka via wheat9)

    HDFS-6351. Command hdfs dfs -rm -r can't remove empty directory.
    (Yongjun Zhang via wang)

    HDFS-5522. Datanode disk error check may be incorrectly skipped.
    (Rushabh S Shah via kihwal)

    HDFS-6367. EnumSetParam$Domain#parse fails for parameter containing more than one enum.
    (Yi Liu via umamahesh)

    HDFS-6305. WebHdfs response decoding may throw RuntimeExceptions (Daryn
    Sharp via jeagles)

    HDFS-6355. Fix divide-by-zero, improper use of wall-clock time in
    BlockPoolSliceScanner (cmccabe)

    HDFS-6370. Web UI fails to display in intranet under IE.
    (Haohui Mai via cnauroth)

    HDFS-6381. Fix a typo in INodeReference.java. (Binglin Chang via jing9)

    HDFS-6400. Cannot execute hdfs oiv_legacy. (Akira AJISAKA via kihwal)

    HDFS-6250. Fix test failed in TestBalancerWithNodeGroup.testBalancerWithRackLocality
    (Binglin Chang and Chen He via junping_du)

    HDFS-4913. Deleting file through fuse-dfs when using trash fails requiring
    root permissions (cmccabe)

    HDFS-6421. Fix vecsum.c compile on BSD and some other systems. (Mit Desai
    via Colin Patrick McCabe)

    HDFS-6419. TestBookKeeperHACheckpoints#TestSBNCheckpoints fails on trunk.
    (Akira AJISAKA via kihwal)

    HDFS-6409. Fix typo in log message about NameNode layout version upgrade.
    (Chen He via cnauroth)

    HDFS-6433. Replace BytesMoved class with AtomicLong.
    (Benoy Antony via cnauroth)

    HDFS-6438. DeleteSnapshot should be a DELETE request in WebHdfs. (jing9)

    HDFS-6423. Diskspace quota usage should be updated when appending data to
    partial block. (jing9)

    HDFS-6443. Fix MiniQJMHACluster related test failures. (Zesheng Wu via
    Arpit Agarwal)

    HDFS-6227. ShortCircuitCache#unref should purge ShortCircuitReplicas whose
    streams have been closed by java interrupts. (Colin Patrick McCabe via jing9)

    HDFS-6442. Fix TestEditLogAutoroll and TestStandbyCheckpoints failure
    caused by port conficts. (Zesheng Wu via Arpit Agarwal)

    HDFS-6448. BlockReaderLocalLegacy should set socket timeout based on
    conf.socketTimeout (liangxie via cmccabe)

    HDFS-6453. Use Time#monotonicNow to avoid system clock reset.
    (Liang Xie via wang)

    HDFS-6461. Use Time#monotonicNow to compute duration in DataNode#shutDown.
    (James Thomas via wang)

    HDFS-6462. NFS: fsstat request fails with the secure hdfs (brandonli)

    HDFS-6404. HttpFS should use a 000 umask for mkdir and create 
    operations. (yoderme via tucu)

    HDFS-6424. blockReport doesn't need to invalidate blocks on SBN. (Ming Ma
    via jing9)

    HDFS-6497. Make TestAvailableSpaceVolumeChoosingPolicy deterministic
    (cmccabe)

    HDFS-6500. Snapshot shouldn't be removed silently after renaming to an 
    existing snapshot. (Nicholas SZE via junping_du)

    HDFS-6257. TestCacheDirectives#testExceedsCapacity fails occasionally
    (cmccabe)

    HDFS-6364. Incorrect check for unknown datanode in Balancer. (Benoy
    Antony via Arpit Agarwal)

    HDFS-6503. Fix typo of DFSAdmin restoreFailedStorage.
    (Zesheng Wu via wheat9)

    HDFS-6464. Support multiple xattr.name parameters for WebHDFS getXAttrs.
    (Yi Liu via umamahesh)

    HDFS-6539. test_native_mini_dfs is skipped in hadoop-hdfs/pom.xml
    (decstery via cmccabe)

    HDFS-6527. Edit log corruption due to defered INode removal. (kihwal and
    jing9 via jing9)

    HDFS-6552. add DN storage to a BlockInfo will not replace the different
    storage from same DN. (Amir Langer via Arpit Agarwal)

    HDFS-6551. Rename with OVERWRITE option may throw NPE when the target
    file/directory is a reference INode. (jing9)

    HDFS-6439. NFS should not reject NFS requests to the NULL procedure whether
    port monitoring is enabled or not. (brandonli)

    HDFS-6559. Fix wrong option "dfsadmin -rollingUpgrade start" in the
    document. (Akira Ajisaka via Arpit Agarwal)

    HDFS-6553. Add missing DeprecationDeltas for NFS Kerberos configurations
    (Stephen Chu via brandonli)

    HDFS-6563. NameNode cannot save fsimage in certain circumstances when
    snapshots are in use. (atm)

    HDFS-3848. A Bug in recoverLeaseInternal method of FSNameSystem class
    (Hooman Peiro Sajjad  and Chen He via kihwal)

    HDFS-6549. Add support for accessing the NFS gateway from the AIX NFS
    client. (atm)

    HDFS-6535. HDFS quota update is wrong when file is appended. (George Wong
    via jing9)

    HDFS-6222. Remove background token renewer from webhdfs.
    (Rushabh Shah and Daryn Sharp via cnauroth)

    HDFS-6580. FSNamesystem.mkdirsInt should call the getAuditFileInfo()
    wrapper. (Zhilei Xu via wheat9)

    HDFS-6587. Bug in TestBPOfferService can cause test failure. (Zhilei Xu
    via Arpit Agarwal)

    HDFS-6598. Fix a typo in message issued from explorer.js. (Yongjun Zhang
    via wheat9)

    HDFS-6475. WebHdfs clients fail without retry because incorrect handling
    of StandbyException. (Yongjun Zhang via atm)

    HADOOP-10701. NFS should not validate the access premission only based on
    the user's primary group (Harsh J via atm)

    HDFS-6556. Refine XAttr permissions (umamahesh)

    HDFS-6601. Issues in finalizing rolling upgrade when there is a layout 
    version change (kihwal)

    HDFS-6418. Regression: DFS_NAMENODE_USER_NAME_KEY missing
    (szetszwo via stevel)

    HDFS-6558. Missing newline in the description of dfsadmin -rollingUpgrade.
    (Chen He via kihwal)

    HDFS-6591. while loop is executed tens of thousands of times in Hedged Read
    (Liang Xie via cnauroth)

    HDFS-6604. The short-circuit cache doesn't correctly time out replicas that
    haven't been used in a while (cmccabe)

    HDFS-4286. Changes from BOOKKEEPER-203 broken capability of including 
    bookkeeper-server jar in hidden package of BKJM (Rakesh R via umamahesh)

    HDFS-4221. Remove the format limitation point from BKJM documentation as HDFS-3810
    closed. (Rakesh R via umamahesh)

    HDFS-5411. Update Bookkeeper dependency to 4.2.3. (Rakesh R via umamahesh)

    HDFS-6631. TestPread#testHedgedReadLoopTooManyTimes fails intermittently.
    (Liang Xie via cnauroth)

    HDFS-6647. Edit log corruption when pipeline recovery occurs for deleted 
    file present in snapshot (kihwal)

    HDFS-6378. NFS registration should timeout instead of hanging when
    portmap/rpcbind is not available (Abhiraj Butala via brandonli)

    HDFS-6632. Reintroduce dfs.http.port / dfs.https.port in branch-2.
    (Yongjun Zhang via wheat9)

    HDFS-6703. NFS: Files can be deleted from a read-only mount
    (Srikanth Upputuri via brandonli)

    HDFS-6422. getfattr in CLI doesn't throw exception or return non-0 return code 
    when xattr doesn't exist. (Charles Lamb via umamahesh)

    HDFS-6696. Name node cannot start if the path of a file under
    construction contains ".snapshot". (wang)

    HDFS-6312. WebHdfs HA failover is broken on secure clusters. 
    (daryn via tucu)

    HDFS-6618. FSNamesystem#delete drops the FSN lock between removing INodes
    from the tree and deleting them from the inode map (kihwal via cmccabe)

    HDFS-6622. Rename and AddBlock may race and produce invalid edits (kihwal
    via cmccabe)

    HDFS-6723. New NN webUI no longer displays decommissioned state for dead node.
    (Ming Ma via wheat9)

    HDFS-6768. Fix a few unit tests that use hard-coded port numbers. (Arpit
    Agarwal)

    HDFS-6793. Missing changes in HftpFileSystem when Reintroduce
    dfs.http.port / dfs.https.port in branch-2. (Juan Yu via wang).

  BREAKDOWN OF HDFS-2006 SUBTASKS AND RELATED JIRAS

    HDFS-6299. Protobuf for XAttr and client-side implementation. (Yi Liu via umamahesh)

    HDFS-6302. Implement XAttr as a INode feature. (Yi Liu via umamahesh)

    HDFS-6309. Javadocs for Xattrs apis in DFSClient and other minor fixups. (Charles Lamb via umamahesh)

    HDFS-6258. Namenode server-side storage for XAttrs. (Yi Liu via umamahesh)

    HDFS-6303. HDFS implementation of FileContext API for XAttrs. (Yi Liu and Charles Lamb via umamahesh)

    HDFS-6324. Shift XAttr helper code out for reuse. (Yi Liu via umamahesh)

    HDFS-6301. NameNode: persist XAttrs in fsimage and record XAttrs modifications to edit log.
    (Yi Liu via umamahesh)

    HDFS-6298. XML based End-to-End test for getfattr and setfattr commands. (Yi Liu via umamahesh)

    HDFS-6314. Test cases for XAttrs. (Yi Liu via umamahesh)

    HDFS-6344. Maximum limit on the size of an xattr. (Yi Liu via umamahesh)

    HDFS-6377. Unify xattr name and value limits into a single limit. (wang)

    HDFS-6373. Remove support for extended attributes on symlinks. (Charles Lamb via wang)

    HDFS-6283. Write end user documentation for xattrs. (wang)

    HDFS-6412. Interface audience and stability annotations missing from
    several new classes related to xattrs. (wang)

    HDFS-6259. Support extended attributes via WebHDFS. (yliu)

    HDFS-6346. Optimize OP_SET_XATTRS by persisting single Xattr entry per setXattr/removeXattr api call
    (Yi Liu via umamahesh)

    HDFS-6331. ClientProtocol#setXattr should not be annotated idempotent.
    (umamahesh via wang)

    HDFS-6335. TestOfflineEditsViewer for XAttr. (Yi Liu via umamahesh)

    HDFS-6343. fix TestNamenodeRetryCache and TestRetryCacheWithHA failures. (umamahesh)

    HDFS-6366. FsImage loading failed with RemoveXattr op (umamahesh)

    HDFS-6357. SetXattr should persist rpcIDs for handling retrycache with Namenode restart and HA
    (umamahesh)

    HDFS-6372. Handle setXattr rpcIDs for OfflineEditsViewer. (umamahesh)

    HDFS-6410. DFSClient unwraps AclException in xattr methods, but those
    methods cannot throw AclException. (wang)

    HDFS-6413. xattr names erroneously handled as case-insensitive.
    (Charles Lamb via cnauroth)

    HDFS-6414. xattr modification operations are based on state of latest
    snapshot instead of current version of inode. (Andrew Wang via cnauroth)

    HDFS-6374. setXAttr should require the user to be the owner of the file
    or directory (Charles Lamb via wang)

    HDFS-6492. Support create-time xattrs and atomically setting multiple
    xattrs. (wang)

Release 2.4.1 - 2014-06-23 

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

    HDFS-6215. Wrong error message for upgrade. (Kihwal Lee via jeagles)

  OPTIMIZATIONS

  BUG FIXES 

    HDFS-6189. Multiple HDFS tests fail on Windows attempting to use a test
    root path containing a colon.  (cnauroth via szetszwo) 

    HDFS-6197. Rolling upgrade rollback on Windows can fail attempting to rename
    edit log segment files to a destination that already exists. (cnauroth)

    HDFS-6198. DataNode rolling upgrade does not correctly identify current
    block pool directory and replace with trash on Windows. (cnauroth)

    HDFS-6206. Fix NullPointerException in DFSUtil.substituteForWildcardAddress.
    (szetszwo) 

    HDFS-6204. Fix TestRBWBlockInvalidation: change the last sleep to a loop.
    (szetszwo) 

    HDFS-6209. TestValidateConfigurationSettings should use random ports.
    (Arpit Agarwal via szetszwo) 

    HDFS-6208. DataNode caching can leak file descriptors. (cnauroth)

    HDFS-6231. DFSClient hangs infinitely if using hedged reads and all eligible
    datanodes die. (cnauroth)

    HDFS-6234. TestDatanodeConfig#testMemlockLimit fails on Windows due to
    invalid file path. (cnauroth)

    HDFS-6235. TestFileJournalManager can fail on Windows due to file locking if
    tests run out of order. (cnauroth)

    HDFS-6229. Race condition in failover can cause RetryCache fail to work.
    (jing9)

    HDFS-6232. OfflineEditsViewer throws a NPE on edits containing ACL
    modifications (ajisakaa via cmccabe)

    HDFS-6236. ImageServlet should use Time#monotonicNow to measure latency.
    (cnauroth)

    HDFS-6245. datanode fails to start with a bad disk even when failed
    volumes is set. (Arpit Agarwal)

    HDFS-2882. DN continues to start up, even if block pool fails to initialize
    (vinayakumarb)

    HDFS-6340. DN can't finalize upgrade. (Rahul Singhal via Arpit Agarwal)

    HDFS-6329. WebHdfs does not work if HA is enabled on NN but logical URI is
    not configured. (kihwal)

    HDFS-6313. WebHdfs may use the wrong NN when configured for multiple HA NNs
    (kihwal)

    HDFS-6326. WebHdfs ACL compatibility is broken. (cnauroth)

    HDFS-6361. TestIdUserGroup.testUserUpdateSetting failed due to out of range
    nfsnobody Id. (Yongjun Zhang via brandonli)

    HDFS-4052. BlockManager#invalidateWork should print log outside the lock.
    (Jing Zhao via suresh)

    HDFS-6362. InvalidateBlocks is inconsistent in usage of DatanodeUuid and
    StorageID. (Arpit Agarwal)

    HDFS-6402. Suppress findbugs warning for failure to override equals and
    hashCode in FsAclPermission. (cnauroth)

    HDFS-6325. Append should fail if the last block has insufficient number of
    replicas (Keith Pak via cos)

    HDFS-6397. NN shows inconsistent value in deadnode count.
    (Mohammad Kamrul Islam via kihwal)

    HDFS-6411. nfs-hdfs-gateway mount raises I/O error and hangs when a 
    unauthorized user attempts to access it (brandonli)

Release 2.4.0 - 2014-04-07 

  INCOMPATIBLE CHANGES

  NEW FEATURES

    HDFS-5698. Use protobuf to serialize / deserialize FSImage. (See breakdown
    of tasks below for features and contributors)

    HDFS-5776 Support 'hedged' reads in DFSClient (Liang Xie via stack)

    HDFS-4685. Implementation of ACLs in HDFS. (See breakdown of tasks below for
    features and contributors)

  IMPROVEMENTS

    HDFS-5781. Use an array to record the mapping between FSEditLogOpCode and 
    the corresponding byte value. (jing9)

    HDFS-5153. Datanode should send block reports for each storage in a
    separate message. (Arpit Agarwal)

    HDFS-5804. HDFS NFS Gateway fails to mount and proxy when using Kerberos.
    (Abin Shahab via jing9)

    HDFS-5859. DataNode#checkBlockToken should check block tokens even if
    security is not enabled. (cmccabe)

    HDFS-5746.  Add ShortCircuitSharedMemorySegment (cmccabe)

    HDFS-4911.  Reduce PeerCache timeout to be commensurate with
    dfs.datanode.socket.reuse.keepalive (cmccabe)

    HDFS-4370. Fix typo Blanacer in DataNode. (Chu Tong via shv)

    HDFS-5929. Add blockpool % usage to HDFS federated nn page.
    (Siqi Li via suresh)

    HDFS-5810. Unify mmap cache and short-circuit file descriptor cache
    (cmccabe)

    HDFS-5940. Minor cleanups to ShortCircuitReplica, FsDatasetCache, and
    DomainSocketWatcher (cmccabe)

    HDFS-5531. Combine the getNsQuota() and getDsQuota() methods in INode.
    (szetszwo)

    HDFS-5285. Flatten INodeFile hierarchy: Replace INodeFileUnderConstruction
    and INodeFileUnderConstructionWithSnapshot with FileUnderContructionFeature.
    (jing9 via szetszwo)

    HDFS-5286. Flatten INodeDirectory hierarchy: Replace INodeDirectoryWithQuota
    with DirectoryWithQuotaFeature.  (szetszwo)

    HDFS-5537. Remove FileWithSnapshot interface.  (jing9 via szetszwo)

    HDFS-5554. Flatten INodeFile hierarchy: Replace INodeFileWithSnapshot with
    FileWithSnapshotFeature.  (jing9 via szetszwo)

    HDFS-5647. Merge INodeDirectory.Feature and INodeFile.Feature. (Haohui Mai
    via jing9)

    HDFS-5632. Flatten INodeDirectory hierarchy: Replace
    INodeDirectoryWithSnapshot with DirectoryWithSnapshotFeature.
    (jing9 via szetszwo)

    HDFS-5715. Use Snapshot ID to indicate the corresponding Snapshot for a
    FileDiff/DirectoryDiff. (jing9)

    HDFS-5726. Fix compilation error in AbstractINodeDiff for JDK7. (jing9)

    HDFS-5768. Consolidate the serialization code in DelegationTokenSecretManager 
    (Haohui Mai via brandonli)

    HDFS-5775. Consolidate the code for serialization in CacheManager
    (Haohui Mai via brandonli)

    HDFS-5768. Consolidate the serialization code in DelegationTokenSecretManager
    (Haohui Mai via brandonli)

    HDFS-5973. add DomainSocket#shutdown method (cmccabe)

    HDFS-5318. Support read-only and read-write paths to shared replicas.
    (Eric Sirianni via Arpit Agarwal)

    HDFS-5868. Make hsync implementation pluggable on the DataNode.
    (Buddy Taylor via Arpit Agarwal)

    HDFS-5935. New Namenode UI FS browser should throw smarter error messages.
    (Travis Thompson via jing9)

    HDFS-5939. WebHdfs returns misleading error code and logs nothing if trying
    to create a file with no DNs in cluster. (Yongjun Zhang via jing9)

    HDFS-6006. Remove duplicate code in FSNameSystem#getFileInfo.
    (Akira Ajisaka via cnauroth)

    HDFS-6018. Exception recorded in LOG when IPCLoggerChannel#close is called.
    (jing9)

    HDFS-3969. Small bug fixes and improvements for disk locations API.
    (Todd Lipcon and Andrew Wang)

    HDFS-6025. Update findbugsExcludeFile.xml. (szetszwo)

    HDFS-6030. Remove an unused constructor in INode.java.  (yzhang via
    cmccabe)

    HDFS-4200. Reduce the size of synchronized sections in PacketResponder.
    (Suresh Srinivas, backported by Andrew Wang, committed by jing9)

    HDFS-5950. The DFSClient and DataNode should use shared memory segments to
    communicate short-circuit information. (cmccabe)

    HDFS-6046. add dfs.client.mmap.enabled (cmccabe)

    HDFS-5321. Clean up the HTTP-related configuration in HDFS (wheat9)

    HDFS-5167. Add metrics about the NameNode retry cache. (Tsuyoshi OZAWA via
    jing9)

    HDFS-6043. Give HDFS daemons NFS3 and Portmap their own OPTS (brandonli)

    HDFS-6044. Add property for setting the NFS look up time for users
    (brandonli)

    HDFS-6061. Allow dfs.datanode.shared.file.descriptor.path to contain
    multiple entries and fall back when needed (cmccabe)

    HDFS-5986. Capture the number of blocks pending deletion on namenode webUI.
    (cnauroth)

    HDFS-6070. Cleanup use of ReadStatistics in DFSInputStream. (wang)

    HDFS-6055. Change default configuration to limit file name length in HDFS.
    (cnauroth)

    HDFS-3405. Checkpointing should use HTTP POST or PUT instead of GET-GET
    to send merged fsimages. (Vinayakumar B via wang)

    HDFS-6085. Improve CacheReplicationMonitor log messages a bit (cmccabe)

    HDFS-6072. Clean up dead code of FSImage. (wheat9)

    HDFS-6080. Improve NFS gateway performance by making rtmax and wtmax
    configurable. (Abin Shahab via brandonli)

    HDFS-6084. Namenode UI - "Hadoop" logo link shouldn't go to hadoop
    homepage. (Travis Thompson via wheat9)

    HDFS-6106. Reduce default for
    dfs.namenode.path.based.cache.refresh.interval.ms (cmccabe)

    HDFS-6090. Use MiniDFSCluster.Builder instead of deprecated constructors.
    (Akira AJISAKA via jing9)

    HDFS-6068. Disallow snapshot names that are also invalid directory names.
    (sathish via szetszwo)

    HDFS-6123. Do not log stack trace for ReplicaAlreadyExistsException and
    SocketTimeoutException.  (szetszwo)

    HDFS-6129. When a replica is not found for deletion, do not throw an
    exception.  (szetszwo)

    HDFS-6138. Add a user guide for how to use viewfs with federation.
    (sanjay and szetszwo via szetszwo)

    HDFS-6120. Fix and improve safe mode log messages. (Arpit Agarwal)

    HDFS-6050. NFS does not handle exceptions correctly in a few places 
    (brandonli)

    HDFS-5138. Support HDFS upgrade in HA. (atm via todd)

    HDFS-6124. Add final modifier to class members. (Suresh Srinivas via
    Arpit Agarwal)

    HDFS-5910. Enhance DataTransferProtocol to allow per-connection choice
    of encryption/plain-text. (Benoy Antony via Arpit Agarwal)

    HDFS-6150. Add inode id information in the logs to make debugging easier.
    (suresh)

  OPTIMIZATIONS

    HDFS-5790. LeaseManager.findPath is very slow when many leases need recovery
    (todd)

  BUG FIXES

    HDFS-5492. Port HDFS-2069 (Incorrect default trash interval in the
    docs) to trunk. (Akira Ajisaka via Arpit Agarwal)

    HDFS-5843. DFSClient.getFileChecksum() throws IOException if checksum is 
    disabled. (Laurent Goujon via jing9)

    HDFS-5856. DataNode.checkDiskError might throw NPE.
    (Josh Elser via suresh)

    HDFS-5828. BlockPlacementPolicyWithNodeGroup can place multiple replicas on
    the same node group when dfs.namenode.avoid.write.stale.datanode is true. 
    (Buddy via junping_du)

    HDFS-5767. NFS implementation assumes userName userId mapping to be unique,
    which is not true sometimes (Yongjun Zhang via brandonli)

    HDFS-5791. TestHttpsFileSystem should use a random port to avoid binding
    error during testing (Haohui Mai via brandonli)

    HDFS-5709. Improve NameNode upgrade with existing reserved paths and path
    components. (Andrew Wang via atm)

    HDFS-5881. Fix skip() of the short-circuit local reader(legacy). (kihwal)

    HDFS-5895. HDFS cacheadmin -listPools has exit_code of 1 when the command
    returns 0 result. (Tassapol Athiapinya via cnauroth)

    HDFS-5807. TestBalancerWithNodeGroup.testBalancerWithNodeGroup fails
    intermittently. (Chen He via kihwal)

    HDFS-5882. TestAuditLogs is flaky (jxiang via cmccabe)

    HDFS-5900. Cannot set cache pool limit of "unlimited" via CacheAdmin.
    (wang)

    HDFS-5886. Potential null pointer deference in RpcProgramNfs3#readlink()
    (brandonli)

    HDFS-4858. HDFS DataNode to NameNode RPC should timeout.
    (Henry Wang via shv)

    HDFS-5879. Some TestHftpFileSystem tests do not close streams.
    (Gera Shegalov via suresh)

    HDFS-5938. Make BlockReaderFactory#BlockReaderPeer a static class to avoid
    a findbugs warning. (cmccabe)

    HDFS-5891. webhdfs should not try connecting the DN during redirection
    (Haohui Mai via brandonli)

    HDFS-5904. TestFileStatus fails intermittently. (Mit Desai via kihwal)

    HDFS-5941. add dfs.namenode.secondary.https-address and
    dfs.namenode.secondary.https-address in hdfs-default.xml.
    (Haohui Mai via cnauroth)

    HDFS-5913. Nfs3Utils#getWccAttr() should check attr parameter against null
    (brandonli)

    HDFS-5934. New Namenode UI back button doesn't work as expected
    (Travis Thompson via brandonli)

    HDFS-5901. NameNode new UI doesn't support IE8 and IE9 on windows 7
    (Vinayakumar B via brandonli)

    HDFS-5943. 'dfs.namenode.https-address' property is not loaded from
    configuration in federation setup. (suresh)

    HDFS-3128. Unit tests should not use a test root in /tmp. (wang)

    HDFS-5948. TestBackupNode flakes with port in use error. (Haohui Mai
    via Arpit Agarwal)

    HDFS-5949. New Namenode UI when trying to download a file, the browser
    doesn't know the file name. (Haohui Mai via brandonli)

    HDFS-5716. Allow WebHDFS to use pluggable authentication filter
    (Haohui Mai via brandonli)

    HDFS-5953. TestBlockReaderFactory fails if libhadoop.so has not been built.
    (Akira Ajisaka via wang)

    HDFS-5759. Web UI does not show up during the period of loading FSImage.
    (Haohui Mai via Arpit Agarwal)

    HDFS-5942. Fix javadoc in OfflineImageViewer. (Akira Ajisaka via cnauroth)

    HDFS-5780. TestRBWBlockInvalidation times out intemittently. (Mit Desai
    via kihwal)

    HDFS-5803. TestBalancer.testBalancer0 fails. (Chen He via kihwal)

    HDFS-5893. HftpFileSystem.RangeHeaderUrlOpener uses the default
    URLConnectionFactory which does not import SSL certificates. (Haohui Mai via
    jing9)

    HDFS-5961. OIV cannot load fsimages containing a symbolic link. (kihwal)

    HDFS-5483. NN should gracefully handle multiple block replicas on same DN.
    (Arpit Agarwal)

    HDFS-5742. DatanodeCluster (mini cluster of DNs) fails to start.
    (Arpit Agarwal)

    HDFS-5979. Typo and logger fix for fsimage PB code. (wang)

    HDFS-5962. Mtime and atime are not persisted for symbolic links. (Akira
    Ajisaka via kihwal)

    HDFS-5944. LeaseManager:findLeaseWithPrefixPath can't handle path like /a/b/
    and cause SecondaryNameNode failed do checkpoint (Yunjiong Zhao via brandonli)

    HDFS-5982. Need to update snapshot manager when applying editlog for deleting
    a snapshottable directory. (jing9)

    HDFS-5988. Bad fsimage always generated after upgrade. (wang)

    HDFS-5922. DN heartbeat thread can get stuck in tight loop. (Arpit Agarwal)

    HDFS-6008. Namenode dead node link is giving HTTP error 500.
    (Benoy Antony via cnauroth)

    HDFS-5936. MiniDFSCluster does not clean data left behind by
    SecondaryNameNode. (Binglin Chang via cnauroth)

    HDFS-5339. WebHDFS URI does not accept logical nameservices when security is
    enabled. (Haohui Mai via jing9)

    HDFS-6033. PBImageXmlWriter incorrectly handles processing cache
    directives. (atm)

    HDFS-5821. TestHDFSCLI fails for user names with the dash character.
    (Gera Shegalov via Arpit Agarwal)

    HDFS-5956. A file size is multiplied by the replication factor in 'hdfs oiv
    -p FileDistribution' option. (Akira Ajisaka via wheat9)

    HDFS-5866. '-maxSize' and '-step' option fail in OfflineImageViewer.
    (Akira Ajisaka via wheat9)

    HDFS-6040. fix DFSClient issue without libhadoop.so and some other
    ShortCircuitShm cleanups (cmccabe)

    HDFS-6053. Fix TestDecommissioningStatus and TestDecommission in branch-2.
    (jing9)

    HDFS-6047 TestPread NPE inside in DFSInputStream hedgedFetchBlockByteRange
    (stack)

    HDFS-6051. HDFS cannot run on Windows since short-circuit shared memory
    segment changes. (cmccabe)

    HDFS-5857. TestWebHDFS#testNamenodeRestart fails intermittently with NPE.
    (Mit Desai via wheat9)

    HDFS-5898. Allow NFS gateway to login/relogin from its kerberos keytab.
    (Abin Shahab via atm)

    HDFS-6057. DomainSocketWatcher.watcherThread should be marked as daemon
    thread (cmccabe)

    HDFS-6058. Fix TestHDFSCLI failures after HADOOP-8691 change.
    (Akira Ajisaka via wheat9)

    HDFS-6062. TestRetryCacheWithHA#testConcat is flaky. (Jing Zhao via wheat9)

    HDFS-6059. TestBlockReaderLocal fails if native library is not available.
    (Akira AJISAKA via Colin Patrick McCabe)

    HDFS-6084. DFSConfigKeys.DFS_BLOCKREPORT_INTERVAL_MSEC_DEFAULT is
    not updated with latest block report interval of 6 hrs.
    (Vinayakumar B via wheat9)

    HDFS-6067. TestPread.testMaxOutHedgedReadPool is flaky (cmccabe)

    HDFS-6065. HDFS zero-copy reads should return null on EOF when doing ZCR
    (cmccabe)

    HDFS-5064. Standby checkpoints should not block concurrent readers.
    (atm via wang)

    HDFS-6078. TestIncrementalBlockReports is flaky. (Arpit Agarwal)

    HDFS-6071. BlockReaderLocal doesn't return -1 on EOF when doing a
    zero-length read on a short file (cmccabe)

    HDFS-6077. Running slive with webhdfs on secure HA cluster fails with unkown
    host exception. (jing9)

    HDFS-6086. Fix a case where zero-copy or no-checksum reads were not allowed
    even when the block was cached (cmccabe)

    HDFS-6079. Timeout for getFileBlockStorageLocations does not work. (wang)

    HDFS-5705. TestSecondaryNameNodeUpgrade#testChangeNsIDFails may fail due
    to ConcurrentModificationException. (Ted Yu via brandonli)

    HDFS-6096. TestWebHdfsTokens may timeout. (szetszwo via Arpit Agarwal)

    HDFS-5244. TestNNStorageRetentionManager#testPurgeMultipleDirs fails.
    (Jinghui Wang via suresh)

    HDFS-6097. zero-copy reads are incorrectly disabled on file offsets above
    2GB (cmccabe)

    HDFS-6102. Lower the default maximum items per directory to fix PB fsimage
    loading. (wang)

    HDFS-6094. The same block can be counted twice towards safe mode
    threshold. (Arpit Agarwal)

    HDFS-5516. WebHDFS does not require user name when anonymous http requests
    are disallowed. (Miodrag Radulovic via cnauroth)

    HDFS-6117. Print file path information in FileNotFoundException on INode
    ID mismatch. (suresh)

    HDFS-6099. HDFS file system limits not enforced on renames. (cnauroth)

    HDFS-6100. DataNodeWebHdfsMethods does not failover in HA mode. (Haohui Mai
    via jing9)

    HDFS-6105. NN web UI for DN list loads the same jmx page multiple times.
    (wheat9)

    HDFS-6127. WebHDFS tokens cannot be renewed in HA setup. (wheat9)

    HDFS-6131. Move HDFSHighAvailabilityWithNFS.apt.vm and 
    HDFSHighAvailabilityWithQJM.apt.vm from Yarn to HDFS. (jing9)

    HDFS-6140. WebHDFS cannot create a file with spaces in the name after HA
    failover changes. (cnauroth)

    HDFS-6135. In HDFS upgrade with HA setup, JournalNode cannot handle layout
    version bump when rolling back. (jing9)

    HDFS-5846. Assigning DEFAULT_RACK in resolveNetworkLocation method can break
    data resiliency. (Nikola Vujic via cnauroth)
    
    HDFS-5840. Follow-up to HDFS-5138 to improve error handling during partial
    upgrade failures. (atm, jing9 and suresh via jing9)

    HDFS-6130. NPE when upgrading namenode from fsimages older than -32.
    (wheat9)

    HDFS-6115. Call flush() for every append on block scan verification log.
    (Vinayakumar B via szetszwo)

    HDFS-5672. TestHASafeMode#testSafeBlockTracking fails in trunk. (jing9)

    HDFS-6157. Fix the entry point of OfflineImageViewer for hdfs.cmd. (wheat9)

    HDFS-6163. Fix a minor bug in the HA upgrade document. (Fengdong Yu via
    jing9)

    HDFS-6166. Change Balancer socket read timeout to 20 minutes and add
    10 seconds delay after error.  (Nathan Roberts via szetszwo)

  BREAKDOWN OF HDFS-5698 SUBTASKS AND RELATED JIRAS

    HDFS-5717. Save FSImage header in protobuf. (Haohui Mai via jing9)

    HDFS-5738. Serialize INode information in protobuf. (Haohui Mai via jing9)

    HDFS-5772. Serialize under-construction file information in FSImage. (jing9)

    HDFS-5783. Compute the digest before loading FSImage. (Haohui Mai via jing9)

    HDFS-5785. Serialize symlink in protobuf. (Haohui Mai via jing9)

    HDFS-5793. Optimize the serialization of PermissionStatus. (Haohui Mai via
    jing9)

    HDFS-5743. Use protobuf to serialize snapshot information. (jing9)

    HDFS-5774. Serialize CachePool directives in protobuf. (Haohui Mai via jing9)

    HDFS-5744. Serialize information for token managers in protobuf. (Haohui Mai
    via jing9)

    HDFS-5824. Add a Type field in Snapshot DiffEntry's protobuf definition.
    (jing9)

    HDFS-5808. Implement cancellation when saving FSImage. (Haohui Mai via jing9)

    HDFS-5826. Update the stored edit logs to be consistent with the changes in
    HDFS-5698 branch. (Haohui Mai via jing9)

    HDFS-5797. Implement offline image viewer. (Haohui Mai via jing9)

    HDFS-5771. Track progress when loading fsimage. (Haohui Mai via cnauroth)

    HDFS-5871. Use PBHelper to serialize CacheDirectiveInfoExpirationProto.
    (Haohui Mai via jing9)

    HDFS-5884. LoadDelegator should use IOUtils.readFully() to read the magic
    header. (Haohui Mai via jing9)

    HDFS-5885. Add annotation for repeated fields in the protobuf definition.
    (Haohui Mai via jing9)

    HDFS-5906. Fixing findbugs and javadoc warnings in the HDFS-5698 branch.
    (Haohui Mai via jing9)

    HDFS-5911. The id of a CacheDirective instance does not get serialized in
    the protobuf-fsimage. (Haohui Mai via jing9)

    HDFS-5915. Refactor FSImageFormatProtobuf to simplify cross section reads.
    (Haohui Mai via cnauroth)

    HDFS-5847. Consolidate INodeReference into a separate section. (jing9)

    HDFS-5959. Fix typo at section name in FSImageFormatProtobuf.java.
    (Akira Ajisaka via suresh)

    HDFS-5981. PBImageXmlWriter generates malformed XML.
    (Haohui Mai via cnauroth)

    HDFS-6107. When a block can't be cached due to limited space on the
    DataNode, that block becomes uncacheable (cmccabe)

    HDFS-6089. Standby NN while transitioning to active throws a connection
    refused error when the prior active NN process is suspended.
    (Jing Zhao via Andrew Wang)

  BREAKDOWN OF HDFS-4685 SUBTASKS AND RELATED JIRAS

    HDFS-5596. Implement RPC stubs. (Haohui Mai via cnauroth)

    HDFS-5685. Implement ACL as a INode feature. (Haohui Mai via cnauroth)

    HDFS-5618. NameNode: persist ACLs in fsimage. (Haohui Mai via cnauroth)

    HDFS-5619. NameNode: record ACL modifications to edit log.
    (Haohui Mai via cnauroth)

    HDFS-5673. Implement logic for modification of ACLs. (cnauroth)

    HDFS-5758. NameNode: complete implementation of inode modifications for
    ACLs. (Chris Nauroth via wheat9)

    HDFS-5612. NameNode: change all permission checks to enforce ACLs in
    addition to permissions. (Chris Nauroth via wheat9)

    HDFS-5613. NameNode: implement handling of ACLs in combination with
    symlinks. (Chris Nauroth via wheat9)

    HDFS-5615. NameNode: implement handling of ACLs in combination with sticky
    bit. (Chris Nauroth via wheat9)

    HDFS-5702. FsShell Cli: Add XML based End-to-End test for getfacl and
    setfacl commands. (Vinay via cnauroth)

    HDFS-5608. WebHDFS: implement ACL APIs.
    (Sachin Jose and Renil Joseph via cnauroth)

    HDFS-5614. NameNode: implement handling of ACLs in combination with
    snapshots. (cnauroth)

    HDFS-5858. Refactor common ACL test cases to be run through multiple
    FileSystem implementations. (cnauroth)

    HDFS-5860. Refactor INodeDirectory getDirectoryXFeature methods to use
    common getFeature helper method. (Jing Zhao via cnauroth)

    HDFS-5861. Add CLI test for Ls output for extended ACL marker.
    (Vinay via cnauroth)

    HDFS-5616. NameNode: implement default ACL handling. (cnauroth)

    HDFS-5899. Add configuration flag to disable/enable support for ACLs.
    (cnauroth)

    HDFS-5914. Incorporate ACLs with the changes from HDFS-5698.
    (Haohui Mai via cnauroth)

    HDFS-5625. Write end user documentation for HDFS ACLs. (cnauroth)

    HDFS-5925. ACL configuration flag must only reject ACL API calls, not ACLs
    present in fsimage or edits. (cnauroth)

    HDFS-5923. Do not persist the ACL bit in the FsPermission.
    (Haohui Mai via cnauroth)

    HDFS-5933. Optimize the FSImage layout for ACLs (Haohui Mai via cnauroth)

    HDFS-5932. Ls should display the ACL bit (Chris Nauroth via wheat9)

    HDFS-5937. Fix TestOfflineEditsViewer on HDFS-4685 branch. (cnauroth)

    HDFS-5737. Replacing only the default ACL can fail to copy unspecified base
    entries from the access ACL. (cnauroth)

    HDFS-5739. ACL RPC must allow null name or unspecified permissions in ACL
    entries. (cnauroth)

    HDFS-5799. Make audit logging consistent across ACL APIs. (cnauroth)

    HDFS-5849. Removing ACL from an inode fails if it has only a default ACL.
    (cnauroth)

    HDFS-5623. NameNode: add tests for skipping ACL enforcement when permission
    checks are disabled, user is superuser or user is member of supergroup.
    (cnauroth)

    HDFS-5908. Change AclFeature to capture list of ACL entries in an
    ImmutableList. (cnauroth)

    HDFS-6028. Print clearer error message when user attempts to delete required
    mask entry from ACL. (cnauroth)

    HDFS-6039. Uploading a File under a Dir with default acls throws "Duplicated
    ACLFeature". (cnauroth)

    HDFS-6063. TestAclCLI fails intermittently when running test 24:
    copyFromLocal. (cnauroth)

    HDFS-6069. Quash stack traces when ACLs are disabled. (cnauroth)

    HDFS-5638. HDFS implementation of FileContext API for ACLs.
    (Vinayakumar B via cnauroth)

HDFS-5535 subtasks:

    HDFS-5496. Make replication queue initialization asynchronous. (Vinay via
    jing9)

    HDFS-5645. Support upgrade marker in editlog streams. (szetszwo)

    HDFS-5752. Add a new DFSAdmin command to query, start and finalize rolling
    upgrade. (szetszwo)

    HDFS-5786. Support QUERY and FINALIZE actions of rolling upgrade. (szetszwo)

    HDFS-5753. Add new Namenode startup options for downgrade and rollback using
    upgrade marker. (szetszwo)

    HDFS-5835. Add a new option for starting Namenode when rolling upgrade is
    in progress. (szetszwo)

    HDFS-5754. Split LayoutVerion into NameNodeLayoutVersion and
    DataNodeLayoutVersion. (Brandon Li via szetszwo)

    HDFS-5848. Add rolling upgrade status to heartbeat response. (szetszwo)

    HDFS-5890. Avoid NPE in Datanode heartbeat. (Vinay via brandonli)

    HDFS-5869. When starting rolling upgrade or NN restarts, NN should create
    a checkpoint right before the upgrade marker.  (szetszwo)

    HDFS-5874. Should not compare DataNode current layout version with that of
    NameNode in DataStrorage. (brandonli)

    HDFS-5889. When starting rolling upgrade, create a fs image for rollback
    so that the standby namenode can create checkpoints during upgrade.
    (szetszwo & jing9)

    HDFS-5907. Add BlockPoolSliceStorage 'trash' to handle block deletions
    during rolling upgrades. (Arpit Agarwal)

    HDFS-5494. Merge Protobuf-based-FSImage code from trunk - fix build
    break after the merge. (Jing Zhao via Arpit Agarwal)

    HDFS-5585. Provide admin commands for data node upgrade (kihwal)

    HDFS-5920. Support rollback of rolling upgrade in NameNode and JournalNodes.
    (jing9)

    HDFS-5945. Add rolling upgrade information to fsimage; and disallow upgrade
    and rolling upgrade to be started simultaneously.  (szetszwo & jing9)

    HDFS-5966. Fix rollback of rolling upgrade in NameNode HA setup.  (jing9
    via szetszwo)

    HDFS-5974. Fix compilation error, NameNodeLayoutVersion and
    DataNodeLayoutVersion after merge from trunk.  (szetszwo)

    HDFS-5963. TestRollingUpgrade#testSecondaryNameNode causes subsequent
    tests to fail. (szetszwo via Arpit Agarwal)

    HDFS-5976. Create unit tests for downgrade and finalize rolling upgrade.
    (Haohui Mai via Arpit Agarwal)

    HDFS-5980. Rollback does not need to load edits.  (jing9 via szetszwo)

    HDFS-5984. Fix TestEditLog and TestStandbyCheckpoints.  (jing9 via szetszwo)

    HDFS-5985. SimulatedFSDataset#disableAndPurgeTrashStorage should not throw
    UnsupportedOperationException. (jing9 via kihwal)

    HDFS-5987. Fix findbugs warnings in Rolling Upgrade branch. (seztszwo via
    Arpit Agarwal)

    HDFS-5992. Fix NPE in MD5FileUtils and update editsStored for
    TestOfflineEditsViewer.  (szetszwo)

    HDFS-5994. Fix TestDataNodeRollingUpgrade.  (Arpit Agarwal via szetszwo)

    HDFS-5999. Do not create rollback fsimage when it already exists. (jing9)

    HDFS-6005. Simplify Datanode rollback and downgrade. (Suresh Srinivas via
    Arpit Agarwal)

    HDFS-6004. Change DFSAdmin for rolling upgrade commands. (szetszwo via
    Arpit Agarwal)

    HDFS-5583. Make DN send an OOB Ack on shutdown before restarting. (kihwal)

    HDFS-5778. Add rolling upgrade user document. (szetszwo)

    HDFS-6003. Add the new -rollingUpgrade startup option to the namenode
    usage message. (Vinayakumar B via szetszwo)

    HDFS-6014. Fix findbug warnings introduced by HDFS-5583. (kihwal)

    HDFS-6015. Fix TestBlockRecovery
    #testRaceBetweenReplicaRecoveryAndFinalizeBlock. (kihwal)

    HDFS-5924. Utilize OOB upgrade message processing for writes. (kihwal)

    HDFS-5498. Improve datanode startup time. (kihwal)

    HDFS-6000. Avoid saving namespace when starting rolling upgrade. (jing9)

    HDFS-6017. Query the status of rolling upgrade in the preparation stage in
    TestRollingUpgrade and TestRollingUpgradeRollback. (Haohui Mai via
    Arpit Agarwal)

    HDFS-6020. Fix the five findbugs warnings. (kihwal)

    HDFS-6019. Standby NN might not checkpoint when processing the rolling
    upgrade marker. (Haohui Mai via jing9)

    HDFS-6023. Test whether the standby NN continues to checkpoint after the
    prepare stage. (Haohui Mai via jing9)

    HDFS-6024. Test whether the NN will reject the downgrade if it has a
    fsimage from a newer release. (Haohui Mai via jing9)

    HDFS-6026. Fix TestDFSUpgrade and TestDataNodeRollingUpgrade.
    (jing9 via szetszwo)

    HDFS-6029. Secondary NN fails to checkpoint after -rollingUpgrade prepare.
    (jing9)

    HDFS-6032. -rollingUpgrade query hits NPE after the NN restarts. (Haohui Mai
    via jing9)

    HDFS-6031. Add back the "-rollingUpgrade started" namenode startup option;
    otherwise, namenode cannot start when the layout version is changed.
    (szetszwo)

    HDFS-6034. Use DataNodeLayoutVersion for DN registration check and do not
    verify layout version if there is a rolling upgrade in progress.  (szetszwo)

    HDFS-6013. add rollingUpgrade information to latest UI.
    (Vinayakumar B via wheat9)

    HDFS-6042. Fix rolling upgrade documentation and error messages. (szetszwo
    via Arpit Agarwal)

    HDFS-6041. Downgrade/Finalize should rename the rollback image instead of
    purging it. (jing9)

    HDFS-6060. NameNode should not check DataNode layout version (brandonli)

    HDFS-6076. DataNode with SimulatedDataSet should not create
    DatanodeRegistration with namenode layout version and namenode node type.
    (szetszwo)

    HDFS-6038. Allow JournalNode to handle editlog produced by new release with
    future layoutversion. (jing9)

    HDFS-4564. Ensure webhdfs returns correct HTTP response codes for denied
    operations. (daryn via acmurthy)

Release 2.3.1 - UNRELEASED

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

  OPTIMIZATIONS

  BUG FIXES 

Release 2.3.0 - 2014-02-18

  INCOMPATIBLE CHANGES

  NEW FEATURES

    HDFS-5122. Support failover and retry in WebHdfsFileSystem for NN HA.
    (Haohui Mai via jing9)

    HDFS-4953. Enable HDFS local reads via mmap.
    (Colin Patrick McCabe via wang).

    HDFS-5342. Provide more information in the FSNamesystem JMX interfaces.
    (Haohui Mai via jing9)

    HDFS-5334. Implement dfshealth.jsp in HTML pages. (Haohui Mai via jing9)

    HDFS-5379. Update links to datanode information in dfshealth.html. (Haohui
    Mai via jing9)

    HDFS-5382. Implement the UI of browsing filesystems in HTML 5 page. (Haohui
    Mai via jing9)

    HDFS-3987. Support webhdfs over HTTPS. (Haohui Mai via jing9)

    HDFS-5444. Choose default web UI based on browser capabilities. (Haohui Mai
    via jing9)

    HDFS-5514. FSNamesystem's fsLock should allow custom implementation (daryn)

    HDFS-2832. Heterogeneous Storages support in HDFS phase 1 - treat DataNode
    as a collection of storages (see breakdown of tasks below for features and
    contributors).

    HDFS-5703. Add support for HTTPS and swebhdfs to HttpFS. (tucu)

    HDFS-4949. Centralized cache management in HDFS (wang and cmccabe)

  IMPROVEMENTS

    HDFS-5360. Improvement of usage message of renameSnapshot and
    deleteSnapshot. (Shinichi Yamashita via wang)

    HDFS-5331. make SnapshotDiff.java to a o.a.h.util.Tool interface implementation. 
    (Vinayakumar B via umamahesh)

    HDFS-4657.  Limit the number of blocks logged by the NN after a block
    report to a configurable value.  (Aaron T. Myers via Colin Patrick
    McCabe)

    HDFS-5344. Make LsSnapshottableDir as Tool interface implementation. (Sathish via umamahesh)

    HDFS-5544. Adding Test case For Checking dfs.checksum type as NULL value. (Sathish via umamahesh)

    HDFS-5568. Support includeSnapshots option with Fsck command. (Vinayakumar B via umamahesh)

    HDFS-4983. Numeric usernames do not work with WebHDFS FS. (Yongjun Zhang via
    jing9)

    HDFS-5592. statechangeLog of completeFile should be logged only in case of success. 
    (Vinayakumar via umamahesh)

    HDFS-5662. Can't decommission a DataNode due to file's replication factor
    larger than the rest of the cluster size. (brandonli)

    HDFS-5068. Convert NNThroughputBenchmark to a Tool to allow generic options.
    (shv)

    HDFS-5675. Add Mkdirs operation to NNThroughputBenchmark.
    (Plamen Jeliazkov via shv)

    HDFS-5677. Need error checking for HA cluster configuration.
    (Vincent Sheffer via cos)

    HDFS-5825. Use FileUtils.copyFile() to implement DFSTestUtils.copyFile().
    (Haohui Mai via Arpit Agarwal)

    HDFS-5267. Remove volatile from LightWeightHashSet. (Junping Du via llu)

    HDFS-4278. Log an ERROR when DFS_BLOCK_ACCESS_TOKEN_ENABLE config is
    disabled but security is turned on. (Kousuke Saruta via harsh)

    HDFS-5004. Add additional JMX bean for NameNode status data. Contributed
    by Trevor Lorimer.

    HDFS-4994. Audit log getContentSummary() calls. (Robert Parker via kihwal)

    HDFS-5144. Document time unit to NameNodeMetrics. (Akira Ajisaka via
    suresh)

    HDFS-4491. Parallel testing HDFS. (Andrey Klochkov via cnauroth)

    HDFS-4879. Add "blocked ArrayList" collection to avoid CMS full GCs
    (Todd Lipcon via Colin Patrick McCabe)

    HDFS-4096. Add snapshot information to namenode WebUI. (Haohui Mai via 
    jing9)

    HDFS-5188. In BlockPlacementPolicy, reduce the number of chooseTarget(..)
    methods; replace HashMap with Map in parameter declarations and cleanup
    some related code.  (szetszwo)

    HDFS-5207. In BlockPlacementPolicy.chooseTarget(..), change the writer
    and the excludedNodes parameter types respectively to Node and Set.
    (Junping Du via szetszwo)

    HDFS-5240. Separate formatting from logging in the audit logger API (daryn)

    HDFS-5191. Revisit zero-copy API in FSDataInputStream to make it more
    intuitive.  (Contributed by Colin Patrick McCabe)

    HDFS-5260. Merge zero-copy memory-mapped HDFS client reads to trunk and
    branch-2. (cnauroth)

    HDFS-4517. Cover class RemoteBlockReader with unit tests. (Vadim Bondarev
    and Dennis Y via kihwal)

    HDFS-4512. Cover package org.apache.hadoop.hdfs.server.common with tests.
    (Vadim Bondarev via kihwal)

    HDFS-4510. Cover classes ClusterJspHelper/NamenodeJspHelper with unit
    tests. (Andrey Klochkov via kihwal)

    HDFS-5323. Remove some deadcode in BlockManager.  (Colin Patrick McCabe)

    HDFS-5338. Add a conf to disable hostname check in datanode registration.
    (szetszwo)

    HDFS-5130. Add test for snapshot related FsShell and DFSAdmin commands.
    (Binglin Chang via jing9)

    HDFS-5374. Remove deadcode in DFSOutputStream. (suresh)

    HDFS-4511. Cover package org.apache.hadoop.hdfs.tools with unit test
    (Andrey Klochkov via jeagles)

    HDFS-4885. Improve the verifyBlockPlacement() API in BlockPlacementPolicy.
    (Junping Du via szetszwo)

    HDFS-5363. Refactor WebHdfsFileSystem: move SPENGO-authenticated connection
    creation to URLConnectionFactory. (Haohui Mai via jing9)

    HDFS-5436. Move HsFtpFileSystem and HFtpFileSystem into org.apache.hdfs.web
    (Haohui Mai via Arpit Agarwal)

    HDFS-5371. Let client retry the same NN when 
    "dfs.client.test.drop.namenode.response.number" is enabled. (jing9)

    HDFS-5467. Remove tab characters in hdfs-default.xml.
    (Shinichi Yamashita via Andrew Wang)

    HDFS-5495. Remove further JUnit3 usages from HDFS.
    (Jarek Jarcec Cecho via Andrew Wang)

    HDFS-5325. Remove WebHdfsFileSystem#ConnRunner. (Haohui Mai via jing9) 

    HDFS-5488. Clean up TestHftpURLTimeout. (Haohui Mai via jing9)

    HDFS-5440. Extract the logic of handling delegation tokens in HftpFileSystem 
    to the TokenAspect class. (Haohui Mai via jing9)

    HDFS-5487. Introduce unit test for TokenAspect. (Haohui Mai via jing9)

    HDFS-4995. Make getContentSummary less expensive. (kihwal)

    HDFS-5506. Use URLConnectionFactory in DelegationTokenFetcher. (Haohui Mai
    via jing9)

    HDFS-5489. Use TokenAspect in WebHDFSFileSystem. (Haohui Mai via jing9)

    HDFS-5393. Serve bootstrap and jQuery locally. (Haohui Mai via jing9)

    HDFS-5073. TestListCorruptFileBlocks fails intermittently. (Arpit Agarwal)

    HDFS-1386. TestJMXGet fails in jdk7 (jeagles)

    HDFS-5532. Enable the webhdfs by default to support new HDFS web UI. (Vinay
    via jing9)

    HDFS-5525. Inline dust templates for new Web UI. (Haohui Mai via jing9)

    HDFS-5561. FSNameSystem#getNameJournalStatus() in JMX should return plain 
    text instead of HTML. (Haohui Mai via jing9)

    HDFS-5581. NameNodeFsck should use only one instance of
    BlockPlacementPolicy. (vinay via cmccabe)

    HDFS-5633. Improve OfflineImageViewer to use less memory. (jing9)

    HDFS-5023. TestSnapshotPathINodes.testAllowSnapshot is failing with jdk7
    (Mit Desai via jeagles)

    HDFS-5637. Try to refeatchToken while local read InvalidToken occurred.
    (Liang Xie via junping_du)

    HDFS-5652. Refactor invalid block token exception handling in DFSInputStream.
    (Liang Xie via junping_du)

    HDFS-5350. Name Node should report fsimage transfer time as a metric.
    (Jimmy Xiang via wang)

    HDFS-5538. URLConnectionFactory should pick up the SSL related configuration 
    by default. (Haohui Mai via jing9)

    HDFS-5545. Allow specifying endpoints for listeners in HttpServer. (Haohui
    Mai via jing9)

    HDFS-5536. Implement HTTP policy for Namenode and DataNode. (Haohui Mai via
    jing9)

    HDFS-5312. Generate HTTP / HTTPS URL in DFSUtil#getInfoServer() based on the 
    configured http policy. (Haohui Mai via jing9)

    HDFS-5629. Support HTTPS in JournalNode and SecondaryNameNode. 
    (Haohui Mai via jing9)

    HDFS-5674. Editlog code cleanup: remove @SuppressWarnings("deprecation") in
    FSEditLogOp; change FSEditLogOpCodes.fromByte(..) to be more efficient; and
    change Some fields in FSEditLog to final.  (szetszwo)

    HDFS-5634. Allow BlockReaderLocal to switch between checksumming and not
    (cmccabe)

    HDFS-5663 make the retry time and interval value configurable in openInfo()
    (Liang Xie via stack)

    HDFS-5540. Fix intermittent failure in TestBlocksWithNotEnoughRacks.
    (Binglin Chang via junping_du)

    HDFS-5695. Clean up TestOfflineEditsViewer and OfflineEditsViewerHelper.
    (Haohui Mai via jing9)

    HDFS-5220. Expose group resolution time as metric (jxiang via cmccabe)

    HDFS-5762. BlockReaderLocal doesn't return -1 on EOF when doing zero-length
    reads (Colin Patrick McCabe)

    HDFS-5766. In DFSInputStream, do not add datanode to deadNodes after
    InvalidEncryptionKeyException in fetchBlockByteRange (Liang Xie via Colin
    Patrick McCabe)

    HDFS-5704. Change OP_UPDATE_BLOCKS with a new OP_ADD_BLOCK. (jing9)

    HDFS-5784. Reserve space in edit log header and fsimage header for feature
    flag section. (Colin Patrick McCabe)

    HDFS-5434. Change block placement policy constructors from package private
    to protected. (Buddy Taylor via Arpit Agarwal)

    HDFS-5788. listLocatedStatus response can be very large. (Nathan Roberts
    via kihwal)

    HDFS-5841. Update HDFS caching documentation with new changes. (wang)

  OPTIMIZATIONS

    HDFS-5239.  Allow FSNamesystem lock fairness to be configurable (daryn)

    HDFS-5341. Reduce fsdataset lock duration during directory scanning.
    (Qus-Jiawei via kihwal)

    HDFS-5681. renewLease should not hold fsn write lock. (daryn via Kihwal)

    HDFS-5241. Provide alternate queuing audit logger to reduce logging
    contention (daryn)

  BUG FIXES

    HDFS-5307. Support both HTTP and HTTPS in jsp pages (Haohui Mai via
    brandonli)

    HDFS-5291. Standby namenode after transition to active goes into safemode.
    (jing9)

    HDFS-5317. Go back to DFS Home link does not work on datanode webUI
    (Haohui Mai via brandonli)

    HDFS-5316. Namenode ignores the default https port (Haohui Mai via
    brandonli)

    HDFS-5281. COMMIT request should not block. (brandonli)

    HDFS-5337. should do hsync for a commit request even there is no pending
    writes (brandonli)

    HDFS-5335. Hive query failed with possible race in dfs output stream.
    (Haohui Mai via suresh)

    HDFS-5322. HDFS delegation token not found in cache errors seen on secure HA 
    clusters. (jing9)

    HDFS-5329. Update FSNamesystem#getListing() to handle inode path in startAfter
    token. (brandonli)

    HDFS-5330. fix readdir and readdirplus for large directories (brandonli)

    HDFS-5370. Typo in Error Message: different between range in condition
    and range in error message. (Kousuke Saruta via suresh)

    HDFS-5365. Fix libhdfs compile error on FreeBSD9. (Radim Kolar via cnauroth)
    
    HDFS-5347. Add HDFS NFS user guide. (brandonli)

    HDFS-5403. WebHdfs client cannot communicate with older WebHdfs servers
    post HDFS-5306. (atm)

    HDFS-5171. NFS should create input stream for a file and try to share it
    with multiple read requests. (Haohui Mai via brandonli)

    HDFS-5413. hdfs.cmd does not support passthrough to any arbitrary class.
    (cnauroth)

    HDFS-5433. When reloading fsimage during checkpointing, we should clear
    existing snapshottable directories. (Aaron T. Myers via wang)

    HDFS-5432. TestDatanodeJsp fails on Windows due to assumption that loopback
    address resolves to host name localhost. (cnauroth)

    HDFS-5065. TestSymlinkHdfsDisable fails on Windows. (ivanmi)

    HDFS-4633 TestDFSClientExcludedNodes fails sporadically if excluded nodes
    cache expires too quickly  (Chris Nauroth via Sanjay)

    HDFS-5037. Active NN should trigger its own edit log rolls. (wang)

    HDFS-5035.  getFileLinkStatus and rename do not correctly check permissions
    of symlinks.  (Andrew Wang via Colin Patrick McCabe)

    HDFS-5456. NameNode startup progress creates new steps if caller attempts to
    create a counter for a step that doesn't already exist.  (cnauroth)

    HDFS-5458. Datanode failed volume threshold ignored if exception is thrown
    in getDataDirsFromURIs. (Mike Mellenthin via wang)

    HDFS-5252. Stable write is not handled correctly in someplace. (brandonli)

    HDFS-5364. Add OpenFileCtx cache. (brandonli)

    HDFS-5469. Add configuration property for the sub-directroy export path
    (brandonli)

    HDFS-5519. COMMIT handler should update the commit status after sync
    (brandonli)

    HDFS-5372. In FSNamesystem, hasReadLock() returns false if the current 
    thread holds the write lock (Vinaykumar B via umamahesh)

    HDFS-4516. Client crash after block allocation and NN switch before lease recovery for 
    the same file can cause readers to fail forever (VinaayKumar B via umamahesh)

    HDFS-5014. Process register commands with out holding BPOfferService lock. 
    (Vinaykumar B via umamahesh)

    HDFS-5288. Close idle connections in portmap (Haohui Mai via brandonli)

    HDFS-5407. Fix typos in DFSClientCache (Haohui Mai via brandonli)

    HDFS-5548. Use ConcurrentHashMap in portmap (Haohui Mai via brandonli)

    HDFS-5577. NFS user guide update (brandonli)

    HDFS-5563. NFS gateway should commit the buffered data when read request comes
    after write to the same file (brandonli)

    HDFS-4997. libhdfs doesn't return correct error codes in most cases (cmccabe)

    HDFS-5587. add debug information when NFS fails to start with duplicate user
    or group names (brandonli)

    HDFS-5590. Block ID and generation stamp may be reused when persistBlocks is 
    set to false. (jing9)

    HDFS-5353. Short circuit reads fail when dfs.encrypt.data.transfer is 
    enabled. (Colin Patrick McCabe via jing9)

    HDFS-5283. Under construction blocks only inside snapshots should not be
    counted in safemode threshhold.  (Vinay via szetszwo)

    HDFS-5257. addBlock() retry should return LocatedBlock with locations else client 
    will get AIOBE. (Vinay via jing9)

    HDFS-5427. Not able to read deleted files from snapshot directly under 
    snapshottable dir after checkpoint and NN restart. (Vinay via jing9)

    HDFS-5443. Delete 0-sized block when deleting an under-construction file that 
    is included in snapshot. (jing9)

    HDFS-5476. Snapshot: clean the blocks/files/directories under a renamed 
    file/directory while deletion. (jing9)

    HDFS-5425. Renaming underconstruction file with snapshots can make NN failure on 
    restart. (jing9 and Vinay)

    HDFS-5474. Deletesnapshot can make Namenode in safemode on NN restarts. 
    (Sathish via jing9)

    HDFS-5504. In HA mode, OP_DELETE_SNAPSHOT is not decrementing the safemode threshold, 
    leads to NN safemode. (Vinay via jing9)

    HDFS-5428. Under construction files deletion after snapshot+checkpoint+nn restart 
    leads nn safemode. (jing9)

    HDFS-5074. Allow starting up from an fsimage checkpoint in the middle of a
    segment. (Todd Lipcon via atm)

    HDFS-4201. NPE in BPServiceActor#sendHeartBeat. (jxiang via cmccabe)

    HDFS-5666. Fix inconsistent synchronization in BPOfferService (jxiang via cmccabe)
    
    HDFS-5657. race condition causes writeback state error in NFS gateway (brandonli)

    HDFS-5661. Browsing FileSystem via web ui, should use datanode's fqdn instead of ip 
    address. (Benoy Antony via jing9)

    HDFS-5582. hdfs getconf -excludeFile or -includeFile always failed (sathish
    via cmccabe)

    HDFS-5671. Fix socket leak in DFSInputStream#getBlockReader. (JamesLi via umamahesh) 

    HDFS-5649. Unregister NFS and Mount service when NFS gateway is shutting down.
    (brandonli)

    HDFS-5789. Some of snapshot APIs missing checkOperation double check in fsn. (umamahesh)

    HDFS-5343. When cat command is issued on snapshot files getting unexpected result.
    (Sathish via umamahesh)

    HDFS-5297. Fix dead links in HDFS site documents. (Akira Ajisaka via
    Arpit Agarwal)

    HDFS-5830. WebHdfsFileSystem.getFileBlockLocations throws
    IllegalArgumentException when accessing another cluster. (Yongjun Zhang via
    Colin Patrick McCabe)

    HDFS-5833. Fix SecondaryNameNode javadoc. (Bangtao Zhou via Arpit Agarwal)

    HDFS-5844. Fix broken link in WebHDFS.apt.vm. (Akira Ajisaka via
    Arpit Agarwal)

    HDFS-5034.  Remove debug prints from GetFileLinkInfo (Andrew Wang via Colin
    Patrick McCabe)

    HDFS-4816. transitionToActive blocks if the SBN is doing checkpoint image
    transfer. (Andrew Wang)

    HDFS-5164.  deleteSnapshot should check if OperationCategory.WRITE is
    possible before taking write lock.  (Colin Patrick McCabe)

    HDFS-5170. BlockPlacementPolicyDefault uses the wrong classname when
    alerting to enable debug logging. (Andrew Wang)

    HDFS-5266. ElasticByteBufferPool#Key does not implement equals. (cnauroth)

    HDFS-5352. Server#initLog() doesn't close InputStream in httpfs. (Ted Yu via
    jing9)

    HDFS-4376. Fix race conditions in Balancer.  (Junping Du via szetszwo)

    HDFS-5375. hdfs.cmd does not expose several snapshot commands. (cnauroth)

    HDFS-5336. DataNode should not output 'StartupProgress' metrics.
    (Akira Ajisaka via cnauroth)

    HDFS-5400.  DFS_CLIENT_MMAP_CACHE_THREAD_RUNS_PER_TIMEOUT constant is set
    to the wrong value.  (Colin Patrick McCabe)

    HDFS-5075. httpfs-config.sh calls out incorrect env script name
    (Timothy St. Clair via stevel)

    HDFS-5438. Flaws in block report processing can cause data loss. (kihwal)

    HDFS-5502. Fix HTTPS support in HsftpFileSystem. (Haohui Mai via jing9)

    HDFS-5552. Fix wrong information of "Cluster summay" in dfshealth.html.
    (Haohui Mai via jing9)

    HDFS-5533. Symlink delete/create should be treated as DELETE/CREATE in snapshot diff 
    report. (Binglin Chang via jing9)

    HDFS-5580. Fix infinite loop in Balancer.waitForMoveCompletion.
    (Binglin Chang via junping_du)

    HDFS-5676. fix inconsistent synchronization of CachingStrategy (cmccabe)

    HDFS-5691. Fix typo in ShortCircuitLocalRead document.
    (Akira Ajisaka via suresh)

    HDFS-5690. DataNode fails to start in secure mode when dfs.http.policy equals to 
    HTTP_ONLY. (Haohui Mai via jing9)

    HDFS-5449. WebHdfs compatibility broken between 2.2 and 1.x / 23.x (kihwal)

    HDFS-5756. hadoopRzOptionsSetByteBufferPool does not accept NULL argument,
    contrary to docs. (cmccabe via wang)

    HDFS-5747. Fix NPEs in BlockManager. (Arpit Agarwal)

    HDFS-5710. FSDirectory#getFullPathName should check inodes against null.
    (Uma Maheswara Rao G via jing9)

    HDFS-5579. Under construction files make DataNode decommission take very long
    hours. (zhaoyunjiong via jing9)

    HDFS-5777. Update LayoutVersion for the new editlog op OP_ADD_BLOCK. (jing9)

    HDFS-5800. Fix a typo in DFSClient.renewLease().  (Kousuke Saruta
    via szetszwo)

    HDFS-5748. Too much information shown in the dfs health page.
    (Haohui Mai via brandonli)

    HDFS-5806. Balancer should set SoTimeout to avoid indefinite hangs.
    (Nathan Roberts via Andrew Wang)

    HDFS-5728. Block recovery will fail if the metafile does not have crc 
    for all chunks of the block (Vinay via kihwal)

    HDFS-5719. FSImage#doRollback() should close prevState before return
    (Ted Yu via todd)

    HDFS-5721. sharedEditsImage in Namenode#initializeSharedEdits() should be
    closed before method returns (Ted Yu via todd)

    HDFS-5845. SecondaryNameNode dies when checkpointing with cache pools.
    (wang)

    HDFS-5842. Cannot create hftp filesystem when using a proxy user ugi and a doAs 
    on a secure cluster. (jing9)

    HDFS-5399. Revisit SafeModeException and corresponding retry policies.
    (Jing Zhao via todd)

    HDFS-5876. SecureDataNodeStarter does not pick up configuration in 
    hdfs-site.xml. (Haohui Mai via jing9)

    HDFS-5873. dfs.http.policy should have higher precedence over dfs.https.enable.
    (Haohui Mai via jing9)

    HDFS-5837. dfs.namenode.replication.considerLoad should consider
    decommissioned nodes. (Tao Luo via shv)

    HDFS-5921. Cannot browse file system via NN web UI if any directory has
    the sticky bit set. (atm)

  BREAKDOWN OF HDFS-2832 SUBTASKS AND RELATED JIRAS

    HDFS-4985. Add storage type to the protocol and expose it in block report
    and block locations. (Arpit Agarwal)

    HDFS-5115. Make StorageID a UUID. (Arpit Agarwal)

    HDFS-5000. DataNode configuration should allow specifying storage type.
    (Arpit Agarwal)

    HDFS-4987. Namenode changes to track multiple storages per datanode.
    (szetszwo)

    HDFS-5154. Fix TestBlockManager and TestDatanodeDescriptor after HDFS-4987.
    (Junping Du via szetszwo)

    HDFS-5009. Include storage information in the LocatedBlock.  (szetszwo)

    HDFS-5134. Move blockContentsStale, heartbeatedSinceFailover and
    firstBlockReport from DatanodeDescriptor to DatanodeStorageInfo; and
    fix a synchronization problem in DatanodeStorageInfo.  (szetszwo)

    HDFS-5157. Add StorageType to FsVolume.  (Junping Du via szetszwo)

    HDFS-4990. Change BlockPlacementPolicy to choose storages instead of
    datanodes.  (szetszwo)

    HDFS-5232. Protocol changes to transmit StorageUuid. (Arpit Agarwal)

    HDFS-5233. Use Datanode UUID to identify Datanodes. (Arpit Agarwal)

    HDFS-5222. Move block schedule information from DatanodeDescriptor to
    DatanodeStorageInfo.  (szetszwo)

    HDFS-4988. Datanode must support all the volumes as individual storages.
    (Arpit Agarwal)

    HDFS-5377. Heartbeats from Datandode should include one storage report
    per storage directory. (Arpit Agarwal)

    HDFS-5398. NameNode changes to process storage reports per storage
    directory. (Arpit Agarwal)

    HDFS-5390. Send one incremental block report per storage directory.
    (Arpit Agarwal)

    HDFS-5401. Fix NPE in Directory Scanner. (Arpit Agarwal)

    HDFS-5417. Fix storage IDs in PBHelper and UpgradeUtilities.  (szetszwo)

    HDFS-5214. Fix NPEs in BlockManager and DirectoryScanner. (Arpit Agarwal)

    HDFS-5435. File append fails to initialize storageIDs. (Junping Du via
    Arpit Agarwal)

    HDFS-5437. Fix TestBlockReport and TestBPOfferService failures. (Arpit
    Agarwal)

    HDFS-5447. Fix TestJspHelper. (Arpit Agarwal)

    HDFS-5452. Fix TestReplicationPolicy and TestBlocksScheduledCounter.

    HDFS-5448. Datanode should generate its ID on first registration. (Arpit
    Agarwal)

    HDFS-5448. Fix break caused by previous checkin for HDFS-5448. (Arpit
    Agarwal)

    HDFS-5455. NN should update storageMap on first heartbeat. (Arpit Agarwal)

    HDFS-5457. Fix TestDatanodeRegistration, TestFsck and TestAddBlockRetry.
    (Contributed by szetszwo)

    HDFS-5466. Update storage IDs when the pipeline is updated. (Contributed
    by szetszwo)

    HDFS-5439. Fix TestPendingReplication. (Contributed by Junping Du, Arpit
    Agarwal)

    HDFS-5470. Add back trunk's reportDiff algorithm to the branch.
    (Contributed by szetszwo)

    HDFS-5472. Fix TestDatanodeManager, TestSafeMode and
    TestNNThroughputBenchmark (Contributed by szetszwo)

    HDFS-5475. NN incorrectly tracks more than one replica per DN. (Arpit
    Agarwal)

    HDFS-5481. Fix TestDataNodeVolumeFailure in branch HDFS-2832. (Contributed
    by Junping Du)

    HDFS-5480. Update Balancer for HDFS-2832. (Contributed by szetszwo)

    HDFS-5486. Fix TestNameNodeMetrics for HDFS-2832. (Arpit Agarwal)

    HDFS-5491. Update editsStored for HDFS-2832. (Arpit Agarwal)

    HDFS-5494. Fix findbugs warnings for HDFS-2832. (Arpit Agarwal)

    HDFS-5508. Fix compilation error after merge. (Contributed by szetszwo)

    HDFS-5501. Fix pendingReceivedRequests tracking in BPServiceActor. (Arpit
    Agarwal)

    HDFS-5510. Fix a findbug warning in DataStorage.java on HDFS-2832 branch.
    (Junping Du via Arpit Agarwal)

    HDFS-5515. Fix TestDFSStartupVersions for HDFS-2832. (Arpit Agarwal)

    HDFS-5527. Fix TestUnderReplicatedBlocks on branch HDFS-2832. (Arpit
    Agarwal)

    HDFS-5547. Fix build break after merge from trunk to HDFS-2832. (Arpit
    Agarwal)

    HDFS-5542. Fix TODO and clean up the code in HDFS-2832. (Contributed by
    szetszwo)

    HDFS-5559. Fix TestDatanodeConfig in HDFS-2832. (Contributed by szetszwo)

    HDFS-5484. StorageType and State in DatanodeStorageInfo in NameNode is
    not accurate. (Eric Sirianni via Arpit Agarwal)

    HDFS-5648. Get rid of FsDatasetImpl#perVolumeReplicaMap. (Arpit Agarwal)

    HDFS-5454. DataNode UUID should be assigned prior to FsDataset
    initialization. (Arpit Agarwal)

    HDFS-5406. Send incremental block reports for all storages in a
    single call. (Arpit Agarwal)

    HDFS-5667. Include DatanodeStorage in StorageReport. (Arpit Agarwal)

  BREAKDOWN OF HDFS-4949 SUBTASKS AND RELATED JIRAS

    HDFS-5049.  Add JNI mlock support.  (Andrew Wang via Colin Patrick McCabe)

    HDFS-5051.  Propagate cache status information from the DataNode to the
    NameNode  (Andrew Wang via Colin Patrick McCabe)

    HDFS-5052. Add cacheRequest/uncacheRequest support to NameNode.
    (Contributed by Colin Patrick McCabe.)

    HDFS-5050.  Add DataNode support for mlock and munlock  (contributed by
    Andrew Wang)

    HDFS-5141. Add cache status information to datanode heartbeat. (Contributed
    by Andrew Wang)

    HDFS-5121.  Add RPCs for creating and manipulating cache pools.
    (Contributed by Colin Patrick McCabe)

    HDFS-5163. Miscellaneous cache pool RPC fixes (Contributed by Colin Patrick
    McCabe)

    HDFS-5169. hdfs.c: translateZCRException: null pointer deref when
    translating some exceptions (Contributed by Colin Patrick McCabe)

    HDFS-5120. Add command-line support for manipulating cache pools. (cmccabe)

    HDFS-5158. Add command-line support for manipulating cache directives.
    (cmccabe)

    HDFS-5198. NameNodeRpcServer must not send back DNA_FINALIZE in reply to a
    cache report. (cmccabe)

    HDFS-5195. Prevent passing null pointer to mlock and munlock. Contributed
    by Chris Nauroth.

    HDFS-5053. NameNode should invoke DataNode APIs to coordinate caching.
    (Andrew Wang)

    HDFS-5201. NativeIO: consolidate getrlimit into NativeIO#getMemlockLimit.
    (Contributed by Colin Patrick McCabe)

    HDFS-5197. Document dfs.cachereport.intervalMsec in hdfs-default.xml.
    Contributed by Chris Nauroth.

    HDFS-5210. Fix some failing unit tests on HDFS-4949 branch. (Contributed by
    Andrew Wang)

    HDFS-5213. Separate PathBasedCacheEntry and PathBasedCacheDirectiveWithId.
    Contributed by Colin Patrick McCabe.

    HDFS-5236. Change PathBasedCacheDirective APIs to be a single value rather
    than batch. (Contributed by Andrew Wang)

    HDFS-5119. Persist CacheManager state in the edit log. (Contributed by
    Andrew Wang)

    HDFS-5190. Move cache pool related CLI commands to CacheAdmin. (Contributed
    by Andrew Wang)

    HDFS-5309. Fix failing caching unit tests. (Andrew Wang)

    HDFS-5314.  Do not expose CachePool type in AddCachePoolOp (Colin Patrick
    McCabe)

    HDFS-5304. Expose if a block replica is cached in getFileBlockLocations.
    (Contributed by Andrew Wang)

    HDFS-5224. Refactor PathBasedCache* methods to use a Path rather than a
    String. Contributed by Chris Nauroth.

    HDFS-5348. Fix error message when dfs.datanode.max.locked.memory is
    improperly configured. (Contributed by Colin Patrick McCabe)

    HDFS-5349. DNA_CACHE and DNA_UNCACHE should be by blockId only (cmccabe)

    HDFS-5358. Add replication field to PathBasedCacheDirective. (Contributed
    by Colin Patrick McCabe)

    HDFS-5359. Allow LightWeightGSet#Iterator to remove elements. (Contributed
    by Colin Patrick McCabe)

    HDFS-5373. hdfs cacheadmin -addDirective short usage does not mention
    -replication parameter. Contributed by Chris Nauroth.

    HDFS-5096. Automatically cache new data added to a cached path (contributed
    by Colin Patrick McCabe)

    HDFS-5383. fix broken caching unit tests (Andrew Wang)

    HDFS-5388. Loading fsimage fails to find cache pools during namenode
    startup (Chris Nauroth via Colin Patrick McCabe)

    HDFS-5203. Concurrent clients that add a cache directive on the same path
    may prematurely uncache each other.  (Chris Nauroth via Colin Patrick McCabe)

    HDFS-5378. In CacheReport, don't send genstamp and length on the wire
    (Contributed by Colin Patrick McCabe)

    HDFS-5385. Caching RPCs are AtMostOnce, but do not persist client ID and
    call ID to edit log.  (Chris Nauroth via Colin Patrick McCabe)

    HDFS-5404 Resolve regressions in Windows compatibility on HDFS-4949 branch.
    Contributed by Chris Nauroth.

    HDFS-5405. Fix possible RetryCache hang for caching RPC handlers in
    FSNamesystem. (Contributed by Andrew Wang)

    HDFS-5419. Fixup test-patch.sh warnings on HDFS-4949 branch. (wang)

    HDFS-5386. Add feature documentation for datanode caching. Contributed by
    Colin Patrick McCabe.

    HDFS-5468. CacheAdmin help command does not recognize commands  (Stephen
    Chu via Colin Patrick McCabe)

    HDFS-5326. add modifyDirective to cacheAdmin (cmccabe)

    HDFS-5394: Fix race conditions in DN caching and uncaching (cmccabe)

    HDFS-5320. Add datanode caching metrics. Contributed by Andrew Wang.

    HDFS-5482. DistributedFileSystem#listPathBasedCacheDirectives must support
    relative paths. Contributed by Colin Patrick McCabe.

    HDFS-5471. CacheAdmin -listPools fails when user lacks permissions to view
    all pools (Andrew Wang via Colin Patrick McCabe)

    HDFS-5450. better API for getting the cached blocks locations. Contributed
    by Andrew Wang.

    HDFS-5485. add command-line support for modifyDirective (cmccabe)

    HDFS-5366. recaching improvements (cmccabe)

    HDFS-5520. loading cache path directives from edit log doesnt update
    nextEntryId (cmccabe)

    HDFS-5512. CacheAdmin -listPools fails with NPE when user lacks permissions
    to view all pools (awang via cmccabe)

    HDFS-5513. CacheAdmin commands fail when using . as the path. Contributed
    by Andrew Wang.

    HDFS-5511. improve CacheManipulator interface to allow better unit testing
    (cmccabe)

    HDFS-5451. Add byte and file statistics to PathBasedCacheEntry. Contributed
    by Colin Patrick McCabe.

    HDFS-5473. Consistent naming of user-visible caching classes and methods
    (cmccabe)

    HDFS-5543. Fix narrow race condition in TestPathBasedCacheRequests
    (cmccabe)

    HDFS-5565. CacheAdmin help should match against non-dashed commands (wang
    via cmccabe)

    HDFS-5556. Add some more NameNode cache statistics, cache pool stats
    (cmccabe)

    HDFS-5562. TestCacheDirectives and TestFsDatasetCache should stub out
    native mlock. Contributed by Colin Patrick McCabe and Akira Ajisaka.

    HDFS-5430. Support TTL on CacheDirectives. Contributed by Andrew Wang.

    HDFS-5555. CacheAdmin commands fail when first listed NameNode is in
    Standby (jxiang via cmccabe)

    HDFS-5626. dfsadmin report shows incorrect values (cmccabe)

    HDFS-5630. Hook up cache directive and pool usage statistics. (wang)

    HDFS-5665. Remove the unnecessary writeLock while initializing CacheManager
    in FsNameSystem Ctor. (Uma Maheswara Rao G via Andrew Wang)

    HDFS-5431. Support cachepool-based limit management in path-based caching.
    (awang via cmccabe)

    HDFS-5679. TestCacheDirectives should handle the case where native code is
    not available. (wang)

    HDFS-5636. Enforce a max TTL per cache pool (awang via cmccabe)

    HDFS-5701. Fix the CacheAdmin -addPool -maxTtl option name. Contributed by
    Stephen Chu.

    HDFS-5708. The CacheManager throws a NPE in the DataNode logs when
    processing cache reports that refer to a block not known to the BlockManager.
    Contributed by Colin Patrick McCabe.

    HDFS-5659. dfsadmin -report doesn't output cache information properly.
    Contributed by Andrew Wang.

    HDFS-5651. Remove dfs.namenode.caching.enabled and improve CRM locking.
    Contributed by Colin Patrick McCabe.

    HDFS-5589. Namenode loops caching and uncaching when data should be
    uncached. (awang via cmccabe)

    HDFS-5724. modifyCacheDirective logging audit log command wrongly as
    addCacheDirective (Uma Maheswara Rao G via Colin Patrick McCabe)

Release 2.2.0 - 2013-10-13

  INCOMPATIBLE CHANGES

  NEW FEATURES

    HDFS-4817.  Make HDFS advisory caching configurable on a per-file basis.
    (Colin Patrick McCabe)

    HDFS-5230. Introduce RpcInfo to decouple XDR classes from the RPC API.
    (Haohui Mai via brandonli)

  IMPROVEMENTS

    HDFS-5246. Make Hadoop nfs server port and mount daemon port
    configurable. (Jinghui Wang via brandonli)

    HDFS-5256. Use guava LoadingCache to implement DFSClientCache. (Haohui Mai
    via brandonli)

    HDFS-5308. Replace HttpConfig#getSchemePrefix with implicit schemes in HDFS 
    JSP. (Haohui Mai via jing9)

  OPTIMIZATIONS

  BUG FIXES

    HDFS-5139. Remove redundant -R option from setrep.

    HDFS-5251. Race between the initialization of NameNode and the http
    server. (Haohui Mai via suresh)

    HDFS-5258. Skip tests in TestHDFSCLI that are not applicable on Windows.
    (Chuan Liu via cnauroth)

    HDFS-5186. TestFileJournalManager fails on Windows due to file handle leaks.
    (Chuan Liu via cnauroth)

    HDFS-5031. BlockScanner scans the block multiple times. (Vinay via Arpit
    Agarwal)

    HDFS-5268. NFS write commit verifier is not set in a few places (brandonli)

    HDFS-5265. Namenode fails to start when dfs.https.port is unspecified.
    (Haohui Mai via jing9)

    HDFS-5255. Distcp job fails with hsftp when https is enabled in insecure
    cluster. (Arpit Agarwal)

    HDFS-5279. Guard against NullPointerException in NameNode JSP pages before
    initialization of FSNamesystem. (cnauroth)

    HDFS-5289. Race condition in TestRetryCacheWithHA#testCreateSymlink causes
    spurious test failure. (atm)

    HDFS-5300. FSNameSystem#deleteSnapshot() should not check owner in case of 
    permissions disabled. (Vinay via jing9)

    HDFS-5306. Datanode https port is not available at the namenode. (Suresh
    Srinivas via brandonli)

    HDFS-5299. DFS client hangs in updatePipeline RPC when failover happened.
    (Vinay via jing9)

    HDFS-5259. Support client which combines appended data with old data
    before sends it to NFS server. (brandonli)

Release 2.1.1-beta - 2013-09-23

  INCOMPATIBLE CHANGES

  NEW FEATURES

    HDFS-4962 Use enum for nfs constants (Nicholas SZE via jing9)

    HDFS-5071 Change hdfs-nfs parent project to hadoop-project (brandonli)

    HDFS-4763 Add script changes/utility for starting NFS gateway (brandonli)

    HDFS-5076 Add MXBean methods to query NN's transaction information and 
    JournalNode's journal status. (jing9)

    HDFS-5104 Support dotdot name in NFS LOOKUP operation (brandonli)

    HDFS-5107 Fix array copy error in Readdir and Readdirplus responses
    (brandonli)

    HDFS-5110 Change FSDataOutputStream to HdfsDataOutputStream for opened
    streams to fix type cast error. (brandonli)

    HDFS-5069 Include hadoop-nfs and hadoop-hdfs-nfs into hadoop dist for
    NFS deployment (brandonli)

    HDFS-4947 Add NFS server export table to control export by hostname or
    IP range (Jing Zhao via brandonli)

    HDFS-5078 Support file append in NFSv3 gateway to enable data streaming
    to HDFS (brandonli)

    HDFS-5136 MNT EXPORT should give the full group list which can mount the
    exports (brandonli)

    HDFS-5118. Provide testing support for DFSClient to drop RPC responses.
    (jing9)

    HDFS-5085. Refactor o.a.h.nfs to support different types of 
    authentications. (jing9)

    HDFS-5067 Support symlink operations in NFS gateway. (brandonli)

    HDFS-5199 Add more debug trace for NFS READ and WRITE. (brandonli)

    HDFS-5234 Move RpcFrameDecoder out of the public API.
    (Haohui Mai via brandonli)

  IMPROVEMENTS

    HDFS-4513. Clarify in the WebHDFS REST API that all JSON respsonses may
    contain additional properties.  (szetszwo)

    HDFS-5061. Make FSNameSystem#auditLoggers an unmodifiable list. 
    (Arpit Agarwal via suresh)

    HDFS-4905. Add appendToFile command to "hdfs dfs". (Arpit Agarwal via
    cnauroth)

    HDFS-4926. Namenode webserver's page has a tooltip that is inconsistent 
    with the datanode HTML link. (Vivek Ganesan via jing9)

    HDFS-5047. Supress logging of full stack trace of quota and lease
    exceptions. (Robert Parker via kihwal)

    HDFS-2933. Improve DataNode Web UI Index Page. (Vivek Ganesan via
    Arpit Agarwal)

    HDFS-5111. Remove duplicated error message for snapshot commands when 
    processing invalid arguments. (jing9)

    HDFS-5045. Add more unit tests for retry cache to cover all AtMostOnce 
    methods. (jing9)

    HDFS-3245. Add metrics and web UI for cluster version summary. (Ravi
    Prakash via kihwal)

    HDFS-5128. Allow multiple net interfaces to be used with HA namenode RPC
    server. (kihwal)

    HDFS-5150. Allow per NN SPN for internal SPNEGO. (kihwal)

    HDFS-4680. Audit logging of delegation tokens for MR tracing. (Andrew Wang)

    HDFS-5212. Refactor RpcMessage and NFS3Response to support different 
    types of authentication information. (jing9)

    HDFS-4971. Move IO operations out of locking in OpenFileCtx. (brandonli and
    jing9)

  OPTIMIZATIONS

  BUG FIXES

    HDFS-5028. LeaseRenewer throws ConcurrentModificationException when timeout.
    (zhaoyunjiong via szetszwo)

    HDFS-5043. For HdfsFileStatus, set default value of childrenNum to -1
    instead of 0 to avoid confusing applications. (brandonli)

    HDFS-4993. Fsck can fail if a file is renamed or deleted. (Robert Parker
    via kihwal)

    HDFS-5091. Support for spnego keytab separate from the JournalNode keytab 
    for secure HA. (jing9)

    HDFS-5055. nn fails to download checkpointed image from snn in some
    setups. (Vinay and suresh via suresh)

    HDFS-4898. BlockPlacementPolicyWithNodeGroup.chooseRemoteRack() fails to
    properly fallback to local rack. (szetszwo)

    HDFS-4632. globStatus using backslash for escaping does not work on Windows.
    (Chuan Liu via cnauroth)

    HDFS-5093. TestGlobPaths should re-use the MiniDFSCluster to avoid failure
    on Windows. (Chuan Liu via cnauroth)

    HDFS-5080. BootstrapStandby not working with QJM when the existing NN is 
    active. (jing9)

    HDFS-5099. Namenode#copyEditLogSegmentsToSharedDir should close
    EditLogInputStreams upon finishing. (Chuan Liu via cnauroth)

    HDFS-2994. If lease soft limit is recovered successfully
    the append can fail. (Tao Luo via shv)

    HDFS-5100. TestNamenodeRetryCache fails on Windows due to incorrect cleanup.
    (Chuan Liu via cnauroth)

    HDFS-5103. TestDirectoryScanner fails on Windows. (Chuan Liu via cnauroth)

    HDFS-5102. Snapshot names should not be allowed to contain slash characters.
    (jing9)

    HDFS-5105. TestFsck fails on Windows. (Chuan Liu via arp)

    HDFS-5106. TestDatanodeBlockScanner fails on Windows due to incorrect path
    format. (Chuan Liu via cnauroth)

    HDFS-4594. WebHDFS open sets Content-Length header to what is specified by
    length parameter rather than how much data is actually returned. (cnauroth)

    HDFS-5124. DelegationTokenSecretManager#retrievePassword can cause deadlock 
    in NameNode. (Daryn Sharp via jing9)

    HDFS-5132. Deadlock in NameNode between SafeModeMonitor#run and 
    DatanodeManager#handleHeartbeat. (kihwal)

    HDFS-5077. NPE in FSNamesystem.commitBlockSynchronization().
    (Plamen Jeliazkov via shv)

    HDFS-5140. Too many safemode monitor threads being created in the standby 
    namenode causing it to fail with out of memory error. (jing9)

    HDFS-5159. Secondary NameNode fails to checkpoint if error occurs
    downloading edits on first checkpoint. (atm)

    HDFS-5192. NameNode may fail to start when 
    dfs.client.test.drop.namenode.response.number is set. (jing9)

    HDFS-5219. Add configuration keys for retry policy in WebHDFSFileSystem.
    (Haohui Mai via jing9)

    HDFS-5231. Fix broken links in the document of HDFS Federation. (Haohui Mai
    via jing9)

    HDFS-5249. Fix dumper thread which may die silently. (brandonli)

Release 2.1.0-beta - 2013-08-22

  INCOMPATIBLE CHANGES

    HDFS-4053. Increase the default block size. (eli)

    HDFS-4305. Add a configurable limit on number of blocks per file, and min
    block size. (Andrew Wang via atm)

    HDFS-4434. Provide a mapping from INodeId to INode. (suresh)

    HDFS-2802. Add HDFS Snapshot feature.  (See breakdown of tasks below for
    subtasks and contributors)

    HDFS-4866. Protocol buffer support cannot compile under C. (Arpit Agarwal via
    cnauroth)

    HDFS-5083. Update the HDFS compatibility version range. (kihwal)

  NEW FEATURES

    HDFS-1804. Add a new block-volume device choosing policy that looks at
    free space. (atm)

    HDFS-4296. Reserve layout version for release 1.2.0. (suresh)

    HDFS-4334. Add a unique id to INode.  (Brandon Li via szetszwo)

    HDFS-4339. Persist inode id in fsimage and editlog. (Brandon Li via
    suresh)

    HDFS-4340. Update addBlock() to inculde inode id as additional argument.
    (Brandon Li via suresh)

    HDFS-4502. JsonUtil.toFileStatus(..) should check if the fileId property
    exists.  (Brandon Li via suresh)

    HDFS-2576. Enhances the DistributedFileSystem's create API so that clients
    can specify favored datanodes for a file's blocks. (ddas)

    HDFS-347. DFS read performance suboptimal when client co-located on nodes
    with data. (Colin Patrick McCabe via todd and atm)

    HADOOP-8562. Enhancements to support Hadoop on Windows Server and Windows
    Azure environments. (See breakdown of tasks below for subtasks and
    contributors)
    
    HDFS-3601. Add BlockPlacementPolicyWithNodeGroup to support block placement
    with 4-layer network topology.  (Junping Du via szetszwo)

    HDFS-3495. Update Balancer to support new NetworkTopology with NodeGroup.
    (Junping Du via szetszwo)

    HDFS-4659 Support setting execution bit for regular files (Brandon Li via sanjay)

    HDFS-4762 Provide HDFS based NFSv3 and Mountd implementation (brandonli)

    HDFS-4372. Track NameNode startup progress. (cnauroth)

    HDFS-4373. Add HTTP API for querying NameNode startup progress. (cnauroth)

    HDFS-4374. Display NameNode startup progress in UI. (cnauroth)

    HDFS-4974. Add Idempotent and AtMostOnce annotations to namenode
    protocol methods. (suresh)

    HDFS-4979. Implement retry cache on Namenode. (suresh)

    HDFS-5025. Record ClientId and CallId in EditLog to enable rebuilding 
    retry cache in case of HA failover. (Jing Zhao via suresh)
    
  IMPROVEMENTS

    HDFS-4461. DirectoryScanner: volume path prefix takes up memory for every
    block that is scanned (Colin Patrick McCabe)

    HDFS-4222. NN is unresponsive and loses heartbeats from DNs when 
    configured to use LDAP and LDAP has issues. (Xiaobo Peng, suresh)

    HDFS-4304. Make FSEditLogOp.MAX_OP_SIZE configurable. (Colin Patrick
    McCabe via atm)

    HDFS-4518. Finer grained metrics for HDFS capacity.
    (Arpit Agarwal via suresh)

    HDFS-4519. Support overriding jsvc binary and log file locations
    when launching secure datanode. (Chris Nauroth via suresh)

    HDFS-4569. Small image transfer related cleanups.
    (Andrew Wang via suresh)

    HDFS-4521. Invalid network toploogies should not be cached. (Colin Patrick
    McCabe via atm)

    HDFS-4246. The exclude node list should be more forgiving, for each output
    stream. (harsh via atm)

    HDFS-4635. Move BlockManager#computeCapacity to LightWeightGSet. (suresh)

    HDFS-4621. Additional logging to help diagnose slow QJM syncs. (todd)

    HDFS-4618. Default transaction interval for checkpoints is too low. (todd)

    HDFS-4525. Provide an API for knowing that whether file is closed or not. 
    (SreeHari via umamahesh)

    HDFS-3940. Add Gset#clear method and clear the block map when namenode is
    shutdown. (suresh)

    HDFS-4679. Namenode operation checks should be done in a consistent
    manner. (suresh)

    HDFS-4693. Some test cases in TestCheckpoint do not clean up after 
    themselves. (Arpit Agarwal, suresh via suresh)

    HDFS-3817. Avoid printing SafeModeException stack trace.
    (Brandon Li via suresh)

    HDFS-4124. Refactor INodeDirectory#getExistingPathINodes() to enable 
    returning more than INode array. (Jing Zhao via suresh)

    HDFS-4151. Change the methods in FSDirectory to pass INodesInPath instead
    of INode[] as a parameter. (szetszwo)

    HDFS-4129. Add utility methods to dump NameNode in memory tree for 
    testing. (szetszwo via suresh)

    HDFS-4152. Add a new class BlocksMapUpdateInfo for the parameter in
    INode.collectSubtreeBlocksAndClear(..). (Jing Zhao via szetszwo)

    HDFS-4206. Change the fields in INode and its subclasses to private.
    (szetszwo)

    HDFS-4215. Remove locking from addToParent(..) since it is used in image
    loading, and add INode.isFile().  (szetszwo)

    HDFS-4243. When replacing an INodeDirectory, the parent pointers of the
    children of the child have to be updated to the new child.  (Jing Zhao
    via szetszwo)

    HDFS-4209. Clean up the addNode/addChild/addChildNoQuotaCheck methods in
    FSDirectory and INodeDirectory. (szetszwo)

    HDFS-4346. Add SequentialNumber as a base class for INodeId and
    GenerationStamp.  (szetszwo)

    HDFS-4721. Speed up lease recovery by avoiding stale datanodes and choosing
    the datanode with the most recent heartbeat as the primary.  (Varun Sharma
    via szetszwo)

    HDFS-4804. WARN when users set the block balanced preference percent below
    0.5 or above 1.0. (Stephen Chu via atm)

    HDFS-4698. Provide client-side metrics for remote reads, local reads, and
    short-circuit reads. (Colin Patrick McCabe via atm)

    HDFS-3498. Support replica removal in BlockPlacementPolicy and make
    BlockPlacementPolicyDefault extensible for reusing code in subclasses.
    (Junping Du via szetszwo)

    HDFS-4234. Use generic code for choosing datanode in Balancer.  (szetszwo)

    HDFS-4880. Print the image and edits file loaded by the namenode in the
    logs. (Arpit Agarwal via suresh)

    HDFS-2572. Remove unnecessary double-check in DN#getHostName. (harsh)

    HDFS-2857. Cleanup BlockInfo class. (suresh)

    HDFS-3009. Remove duplicate code in DFSClient#isLocalAddress by using 
    NetUtils. (Hari Mankude via suresh)

    HDFS-4914. Use DFSClient.Conf instead of Configuration.  (szetszwo)

    HDFS-4883. complete() should verify fileId. (Tao Luo via shv)

    HDFS-4772. Add number of children in HdfsFileStatus. (brandonli)

    HDFS-4932. Avoid a wide line on the name node webUI if we have more Journal
    nodes. (Fengdong Yu via cnauroth)

    HDFS-4908. Reduce snapshot inode memory usage.  (szetszwo)

    HDFS-4645. Move from randomly generated block ID to sequentially generated
    block ID.  (Arpit Agarwal via szetszwo)

    HDFS-4912. Cleanup FSNamesystem#startFileInternal. (suresh)

    HDFS-4903. Print trash configuration and trash emptier state in
    namenode log. (Arpit Agarwal via suresh)

    HDFS-4992. Make balancer's mover thread count and dispatcher thread count
    configurable.  (Max Lapan via szetszwo)

    HDFS-4996. ClientProtocol#metaSave can be made idempotent by overwriting the
    output file instead of appending to it. (cnauroth)

    HADOOP-9418.  Add symlink support to DistributedFileSystem (Andrew Wang via
    Colin Patrick McCabe)

    HDFS-5007. Replace hard-coded property keys with DFSConfigKeys fields. 
    (Kousuke Saruta via jing9)

    HDFS-5008. Make ClientProtocol#abandonBlock() idempotent. (jing9)

    HADOOP-9760. Move GSet and related classes to common from HDFS.
    (suresh)

    HDFS-5020. Make DatanodeProtocol#blockReceivedAndDeleted idempotent. 
    (jing9)

    HDFS-5024. Make DatanodeProtocol#commitBlockSynchronization idempotent. 
    (Arpit Agarwal via jing9)

    HDFS-3880. Use Builder to build RPC server in HDFS.
    (Brandon Li and Junping Du via szetszwo)

  OPTIMIZATIONS

    HDFS-4465. Optimize datanode ReplicasMap and ReplicaInfo. (atm)

    HDFS-5027. On startup, DN should scan volumes in parallel. (atm)

  BUG FIXES

    HDFS-4626. ClientProtocol#getLinkTarget should throw an exception for
    non-symlink and non-existent paths.  (Andrew Wang via cmccabe)

    HDFS-3934. duplicative dfs_hosts entries handled wrong. (Colin Patrick
    McCabe)
    
    HDFS-4470. Several HDFS tests attempt file operations on invalid HDFS
    paths when running on Windows. (Chris Nauroth via suresh)

    HDFS-4471. Namenode WebUI file browsing does not work with wildcard
    addresses configured. (Andrew Wang via atm)

    HDFS-4342. Directories configured in dfs.namenode.edits.dir.required
    but not in dfs.namenode.edits.dir are silently ignored.  (Arpit Agarwal
    via szetszwo)

    HDFS-4482. ReplicationMonitor thread can exit with NPE due to the race 
    between delete and replication of same file. (umamahesh)

    HDFS-4269. Datanode rejects all datanode registrations from localhost
    in single-node developer setup on Windows. (Chris Nauroth via suresh)

    HDFS-4235. When outputting XML, OfflineEditsViewer can't handle some edits
    containing non-ASCII strings. (Colin Patrick McCabe via atm)

    HDFS-4541. Set hadoop.log.dir and hadoop.id.str when starting secure
    datanode to write the logs to right dir by default. (Arpit Gupta via
    suresh)

    HDFS-4540. Namenode http server should use the web authentication 
    keytab for spnego principal. (Arpit Gupta via suresh)

    HDFS-4544. Error in deleting blocks should not do check disk, for
    all types of errors. (Arpit Agarwal via suresh)

    HDFS-4565. Use DFSUtil.getSpnegoKeytabKey() to get the spnego keytab key
    in secondary namenode and namenode http server. (Arpit Gupta via suresh)

    HDFS-4571. WebHDFS should not set the service hostname on the server side. 
    (tucu)

    HDFS-4013. TestHftpURLTimeouts throws NPE. (Chao Shi via suresh)

    HDFS-4592. Default values for access time precision are out of sync between
    hdfs-default.xml and the code. (atm)

    HDFS-4522. LightWeightGSet expects incrementing a volatile to be atomic.
    (Colin Patrick McCabe via atm)

    HDFS-4484. libwebhdfs compilation broken with gcc 4.6.2. (Colin Patrick
    McCabe via atm)

    HDFS-4595. When short circuit read is fails, DFSClient does not fallback
    to regular reads. (suresh)

    HDFS-4583. TestNodeCount fails. (Ivan Mitic via suresh)

    HDFS-4591. HA clients can fail to fail over while Standby NN is performing
    long checkpoint. (atm)

    HDFS-3277. fail over to loading a different FSImage if the first one we
    try to load is corrupt. (Colin Patrick McCabe and Andrew Wang via atm)

    HDFS-4596. Shutting down namenode during checkpointing can lead to md5sum
    error. (Andrew Wang via atm)

    HDFS-4614. FSNamesystem#getContentSummary should use getPermissionChecker
    helper method. (atm)

    HDFS-4620. Documentation for dfs.namenode.rpc-address specifies wrong
    format. (Sandy Ryza via atm)

    HDFS-4609. TestAuditLogs should release log handles between tests. 
    (Ivan Mitic via szetszwo)

    HDFS-4598. Fix the default value of ConcatSourcesParam and the WebHDFS doc.
    (szetszwo)

    HDFS-4655. DNA_FINALIZE is logged as being an unknown command by the DN
    when received from the standby NN. (atm)

    HDFS-4656. DN heartbeat loop can be briefly tight. (atm)

    HDFS-4658. Standby NN will log that it has received a block report "after
    becoming active" (atm)

    HDFS-4646. createNNProxyWithClientProtocol ignores configured timeout
    value (Jagane Sundar via cos)

    HDFS-3981. Fix handling of FSN lock in getBlockLocations. (Xiaobo Peng
    and todd via todd)

    HDFS-4676. TestHDFSFileSystemContract should set MiniDFSCluster variable
    to null to free up memory. (suresh)

    HDFS-4669. TestBlockPoolManager fails using IBM java. (Tian Hong Wang via
    suresh)

    HDFS-4643. Fix flakiness in TestQuorumJournalManager. (todd)

    HDFS-4639. startFileInternal() should not increment generation stamp.
    (Plamen Jeliazkov via shv)

    HDFS-4695. TestEditLog leaks open file handles between tests.
    (Ivan Mitic via suresh)

    HDFS-4737. JVM path embedded in fuse binaries. (Sean Mackrory via atm)

    HDFS-4739. NN can miscalculate the number of extra edit log segments to
    retain. (atm)

    HDFS-4745. TestDataTransferKeepalive#testSlowReader has race condition that
    causes sporadic failure. (Chris Nauroth via suresh)

    HDFS-4768. File handle leak in datanode when a block pool is removed.
    (Chris Nauroth via suresh)

    HDFS-4748. MiniJournalCluster#restartJournalNode leaks resources, which 
    causes sporadic test failures. (Chris Nauroth via suresh)

    HDFS-4733. Make HttpFS username pattern configurable. (tucu via atm)

    HDFS-4778. Fixes some issues that the first patch on HDFS-2576 missed.
    (ddas)

    HDFS-4785. Concat operation does not remove concatenated files from
    InodeMap. (suresh)

    HDFS-4784. NPE in FSDirectory.resolvePath(). (Brandon Li via suresh)

    HDFS-4810. several HDFS HA tests have timeouts that are too short. (Chris
    Nauroth via atm)

    HDFS-4799. Corrupt replica can be prematurely removed from 
    corruptReplicas map. (todd via kihwal)

    HDFS-4751. TestLeaseRenewer#testThreadName flakes. (Andrew Wang via atm)

    HDFS-4533. start-dfs.sh ignores additional parameters besides -upgrade.
    (Fengdong Yu via suresh)

    HDFS-4765. Permission check of symlink deletion incorrectly throws
    UnresolvedLinkException. (Andrew Wang via atm)

    HDFS-4300. TransferFsImage.downloadEditsToStorage should use a tmp file for
    destination. (Andrew Wang via atm)

    HDFS-4813. Add volatile to BlocksMap.blocks so that the replication thread
    can see the updated value.  (Jing Zhao via szetszwo)

    HDFS-3180. Add socket timeouts to WebHdfsFileSystem.  (Chris Nauroth via
    szetszwo)

    HDFS-4787. Create a new HdfsConfiguration before each TestDFSClientRetries
    testcases. (Tian Hong Wang via atm)

    HDFS-4830. Typo in config settings for AvailableSpaceVolumeChoosingPolicy
    in hdfs-default.xml. (atm)

    HDFS-4824. FileInputStreamCache.close leaves dangling reference to
    FileInputStreamCache.cacheCleaner. (Colin Patrick McCabe via todd)

    HDFS-4298. StorageRetentionManager spews warnings when used with QJM. (atm)

    HDFS-4725. Fix HDFS file handle leaks in FSEditLog, NameNode,
    OfflineEditsBinaryLoader and some tests.  (Chris Nauroth via szetszwo)

    HDFS-4825. webhdfs / httpfs tests broken because of min block size change.
    (Andrew Wang via suresh)

    HDFS-4780. Use the correct relogin method for services. (Robert Parker via
    kihwal)

    HDFS-4827. Slight update to the implementation of API for handling favored
    nodes in DFSClient (ddas)

    HDFS-4865. Remove sub resource warning from httpfs log at startup time. 
    (ywskycn via tucu)

    HDFS-4240. For nodegroup-aware block placement, when a node is excluded,
    the nodes in the same nodegroup should also be excluded.  (Junping Du
    via szetszwo)

    HDFS-4261. Fix bugs in Balaner causing infinite loop and
    TestBalancerWithNodeGroup timeing out.  (Junping Du via szetszwo)

    HDFS-4382. Fix typo MAX_NOT_CHANGED_INTERATIONS. (Ted Yu via suresh)

    HDFS-4840. ReplicationMonitor gets NPE during shutdown. (kihwal)

    HDFS-4815. TestRBWBlockInvalidation: Double call countReplicas() to fetch
    corruptReplicas and liveReplicas is not needed. (Tian Hong Wang via atm)

    HADOOP-8957 HDFS tests for AbstractFileSystem#IsValidName should be overridden for
    embedded file systems like ViewFs (Chris Nauroth via Sanjay Radia)

    HDFS-4586. TestDataDirs.testGetDataDirsFromURIs fails with all directories
    in dfs.datanode.data.dir are invalid. (Ivan Mitic via atm)

    HDFS-3792. Fix two findbugs introduced by HDFS-3695 (todd)

    HADOOP-9635 Fix potential Stack Overflow in DomainSocket.c (V. Karthik Kumar
                via cmccabe)

    HDFS-3163. TestHDFSCLI.testAll fails if the user name is not all lowercase.
    (Brandon Li via atm)

    HDFS-4845. FSNamesystem.deleteInternal should acquire write-lock before
    changing the inode map.  (Arpit Agarwal via szetszwo)

    HDFS-4910. TestPermission failed in branch-2. (Chuan Liu via cnauroth)

    HDFS-4906. HDFS Output streams should not accept writes after being
    closed. (atm)

    HDFS-4917. Start-dfs.sh cannot pass the parameters correctly.
    (Fengdong Yu via suresh)

    HDFS-4205. fsck fails with symlinks. (jlowe)

    HDFS-4927. CreateEditsLog creates inodes with an invalid inode ID, which then
    cannot be loaded by a namenode. (cnauroth)

    HDFS-4944. WebHDFS cannot create a file path containing characters that must
    be URI-encoded, such as space. (cnauroth)

    HDFS-4888. Refactor and fix FSNamesystem.getTurnOffTip. (Ravi Prakash via
    kihwal)

    HDFS-4943. WebHdfsFileSystem does not work when original file path has
    encoded chars.  (Jerry He via szetszwo)

    HDFS-4954. In nfs, OpenFileCtx.getFlushedOffset() should handle IOException.
    (Brandon Li via szetszwo)

    HDFS-4948. mvn site for hadoop-hdfs-nfs fails. (brandonli)

    HDFS-4887. TestNNThroughputBenchmark exits abruptly. (kihwal)

    HDFS-4980. Incorrect logging.properties file for hadoop-httpfs.
    (Mark Grover via suresh)

    HDFS-4999. Fix TestShortCircuitLocalRead on branch-2. (cmccabe via kihwal)

    HDFS-4687. TestDelegationTokenForProxyUser#testWebHdfsDoAs is flaky with
    JDK7. (Andrew Wang via atm)

    HDFS-5003. TestNNThroughputBenchmark failed caused by existing directories.
    (Xi Fang via cnauroth)

    HDFS-5018. Misspelled DFSConfigKeys#DFS_NAMENODE_STALE_DATANODE_INTERVAL_DEFAULT
    in javadoc of DatanodeInfo#isStale(). (Ted Yu via jing9)

    HDFS-4602. TestBookKeeperHACheckpoints fails. (umamahesh)

    HDFS-5016. Deadlock in pipeline recovery causes Datanode to be marked dead.
    (suresh)

    HDFS-5228. The RemoteIterator returned by DistributedFileSystem.listFiles
    may throw NullPointerException.  (szetszwo and cnauroth via szetszwo)

  BREAKDOWN OF HDFS-347 SUBTASKS AND RELATED JIRAS

    HDFS-4353. Encapsulate connections to peers in Peer and PeerServer classes.
    (Colin Patrick McCabe via todd)

    HDFS-4354. Create DomainSocket and DomainPeer and associated unit tests.
    (Colin Patrick McCabe via todd)
    
    HDFS-4356. BlockReaderLocal should use passed file descriptors rather than paths.
    (Colin Patrick McCabe via todd)
    
    HDFS-4388. DomainSocket should throw AsynchronousCloseException when appropriate.
    (Colin Patrick McCabe via todd)
    
    HDFS-4390. Bypass UNIX domain socket unit tests when they cannot be run.
    (Colin Patrick McCabe via todd)
    
    HDFS-4400. DFSInputStream#getBlockReader: last retries should ignore the cache
    (Colin Patrick McCabe via todd)
    
    HDFS-4401. Fix bug in DomainSocket path validation
    (Colin Patrick McCabe via todd)
    
    HDFS-4402. Some small DomainSocket fixes: avoid findbugs warning, change
    log level, etc. (Colin Patrick McCabe via todd)
    
    HDFS-4418. increase default FileInputStreamCache size (todd)
    
    HDFS-4416. Rename dfs.datanode.domain.socket.path to dfs.domain.socket.path
    (Colin Patrick McCabe via todd)
    
    HDFS-4417. Fix case where local reads get disabled incorrectly
    (Colin Patrick McCabe and todd via todd)
    
    HDFS-4433. Make TestPeerCache not flaky (Colin Patrick McCabe via todd)
    
    HDFS-4438. TestDomainSocket fails when system umask is set to 0002. (Colin
    Patrick McCabe via atm)
    
    HDFS-4440. Avoid annoying log message when dfs.domain.socket.path is not
    set. (Colin Patrick McCabe via atm)
    
    HDFS-4473. Don't create domain socket unless we need it. (Colin Patrick McCabe via atm)
    
    HDFS-4485. DN should chmod socket path a+w. (Colin Patrick McCabe via atm)
    
    HDFS-4453. Make a simple doc to describe the usage and design of the
    shortcircuit read feature. (Colin Patrick McCabe via atm)
    
    HDFS-4496. DFSClient: don't create a domain socket unless we need it (Colin
    Patrick McCabe via todd)
    
    HDFS-347: style cleanups (Colin Patrick McCabe via atm)
    
    HDFS-4538. Allow use of legacy blockreader (Colin Patrick McCabe via todd)

    HDFS-4661. A few little code cleanups of some HDFS-347-related code. (Colin
    Patrick McCabe via atm)

  BREAKDOWN OF HADOOP-8562 and HDFS-3602 SUBTASKS AND RELATED JIRAS

    HDFS-4145. Merge hdfs cmd line scripts from branch-1-win. (David Lao,
    Bikas Saha, Lauren Yang, Chuan Liu, Thejas M Nair and Ivan Mitic via suresh)

    HDFS-4163. HDFS distribution build fails on Windows. (Chris Nauroth via
    suresh)

    HDFS-4316. branch-trunk-win contains test code accidentally added during 
    work on fixing tests on Windows. (Chris Nauroth via suresh)

    HDFS-4297. Fix issues related to datanode concurrent reading and writing on
    Windows. (Arpit Agarwal, Chuan Liu via suresh)

    HDFS-4573. Fix TestINodeFile on Windows. (Arpit Agarwal via suresh)

    HDFS-4572. Fix TestJournal failures on Windows. (Arpit Agarwal via suresh)

    HDFS-4287. HTTPFS tests fail on Windows. (Chris Nauroth via suresh)

    HDFS-4593. TestSaveNamespace fails on Windows. (Arpit Agarwal via suresh)

    HDFS-4582. TestHostsFiles fails on Windows. (Ivan Mitic via suresh)

    HDFS-4603. TestMiniDFSCluster fails on Windows. (Ivan Mitic via suresh)

    HDFS-4604. TestJournalNode fails on Windows. (Ivan Mitic via suresh)

    HDFS-4607.  In TestGetConf.testGetSpecificKey(), use a platform-specific
    line separator; otherwise, it fails on Windows.  (Ivan Mitic via szetszwo)

    HDFS-4625. Make TestNNWithQJM#testNewNamenodeTakesOverWriter work on
    Windows. (Ivan Mitic via suresh)

    HDFS-4674. TestBPOfferService fails on Windows due to failure parsing 
    datanode data directory as URI. (Chris Nauroth via suresh)

    HDFS-4615. Fix TestDFSShell failures on Windows.  (Arpit Agarwal
    via szetszwo)

    HDFS-4584. Skip TestNNWithQJM.testNewNamenodeTakesOverWriter() on Windows.
    (Arpit Agarwal via szetszwo)

    HDFS-4732. Fix TestDFSUpgradeFromImage which fails on Windows due to
    failure to unpack old image tarball that contains hard links.
    (Chris Nauroth via szetszwo)

    HDFS-4741. TestStorageRestore#testStorageRestoreFailure fails on Windows.
    (Arpit Agarwal via suresh)

    HDFS-4743. TestNNStorageRetentionManager fails on Windows.
    (Chris Nauroth via suresh)

    HDFS-4740. Fixes for a few test failures on Windows.
    (Arpit Agarwal via suresh)

    HDFS-4722. TestGetConf#testFederation times out on Windows.
    (Ivan Mitic via suresh)

    HDFS-4705. Address HDFS test failures on Windows because of invalid
    dfs.namenode.name.dir. (Ivan Mitic via suresh)

    HDFS-4734. HDFS Tests that use ShellCommandFencer are broken on Windows.
    (Arpit Agarwal via suresh)

    HDFS-4610. Use common utils FileUtil#setReadable/Writable/Executable and 
    FileUtil#canRead/Write/Execute. (Ivan Mitic via suresh)

    HDFS-4677. Editlog should support synchronous writes. (ivanmi)

    HDFS-4752. TestRBWBlockInvalidation fails on Windows due to file locking.
    (Chris Nauroth via suresh)

    HDFS-4783. TestDelegationTokensWithHA#testHAUtilClonesDelegationTokens fails
    on Windows. (cnauroth)

    HDFS-4818. Several HDFS tests that attempt to make directories unusable do
    not work correctly on Windows. (cnauroth)

  BREAKDOWN OF HDFS-2802 HDFS SNAPSHOT SUBTASKS AND RELATED JIRAS

    HDFS-4076. Support snapshot of single files.  (szetszwo)

    HDFS-4082. Add editlog opcodes for snapshot create and delete operations.
    (suresh via szetszwo)

    HDFS-4086. Add editlog opcodes to allow and disallow snapshots on a
    directory. (Brandon Li via suresh)

    HDFS-4083. Protocol changes for snapshots. (suresh)

    HDFS-4077. Add support for Snapshottable Directory. (szetszwo via suresh)

    HDFS-4087. Protocol changes for listSnapshots functionality.
    (Brandon Li via suresh)

    HDFS-4079. Add SnapshotManager which maintains a list for all the
    snapshottable directories and supports snapshot methods such as setting a
    directory to snapshottable and creating a snapshot.  (szetszwo)

    HDFS-4078. Handle replication in snapshots.  (szetszwo)

    HDFS-4084. Provide CLI support to allow and disallow snapshot
    on a directory. (Brondon Li via suresh)

    HDFS-4091. Add snapshot quota to limit the number of snapshots allowed.
    (szetszwo)

    HDFS-4097. Provide CLI support for createSnapshot. (Brandon Li via suresh)

    HDFS-4092. Update file deletion logic for snapshot so that the current inode
    is removed from the circular linked list; and if some blocks at the end of
    the block list no longer belong to any other inode, collect them and update
    the block list.  (szetszwo)

    HDFS-4111. Support snapshot of subtrees. (szetszwo via suresh)

    HDFS-4119. Complete the allowSnapshot code and add a test for it. (szetszwo)

    HDFS-4133. Add testcases for testing basic snapshot functionalities.
    (Jing Zhao via suresh)

    HDFS-4116. Add auditlog for some snapshot operations. (Jing Zhao via suresh)

    HDFS-4095. Add some snapshot related metrics. (Jing Zhao via suresh)

    HDFS-4141. Support directory diff - the difference between the current state
    and a previous snapshot of an INodeDirectory. (szetszwo)

    HDFS-4146. Use getter and setter in INodeFileWithLink to access blocks and
    initialize root directory as snapshottable. (szetszwo)

    HDFS-4149. Implement the disallowSnapshot(..) in FSNamesystem and add
    resetSnapshottable(..) to SnapshotManager. (szetszwo)

    HDFS-4147. When there is a snapshot in a subtree, deletion of the subtree
    should fail. (Jing Zhao via szetszwo)

    HDFS-4150.  Update the inode in the block map when a snapshotted file or a
    snapshot file is deleted. (Jing Zhao via szetszwo)

    HDFS-4159. Rename should fail when the destination directory is
    snapshottable and has snapshots. (Jing Zhao via szetszwo)

    HDFS-4170. Add snapshot information to INodesInPath.  (szetszwo)

    HDFS-4177. Add a snapshot parameter to INodeDirectory.getChildrenList() for
    selecting particular snapshot children list views.  (szetszwo)

    HDFS-4148. Disallow write/modify operations on files and directories in a
    snapshot. (Brandon Li via suresh)

    HDFS-4188. Add Snapshot.ID_COMPARATOR for comparing IDs and fix a bug in
    ReadOnlyList.Util.binarySearch(..).  (szetszwo)

    HDFS-4187. Add tests for replication handling in snapshots. (Jing Zhao via
    szetszwo)

    HDFS-4196. Support renaming of snapshots. (Jing Zhao via szetszwo)

    HDFS-4175. Additional snapshot tests for more complicated directory
    structure and modifications. (Jing Zhao via suresh)

    HDFS-4293. Fix TestSnapshot failure. (Jing Zhao via suresh)

    HDFS-4317. Change INode and its subclasses to support HDFS-4103. (szetszwo)

    HDFS-4103. Support O(1) snapshot creation. (szetszwo)

    HDFS-4330. Support snapshots up to the snapshot limit. (szetszwo)

    HDFS-4357. Fix a bug that if an inode is replaced, further INode operations
    should apply to the new inode. (Jing Zhao via szetszwo)

    HDFS-4230. Support listing of all the snapshottable directories.  (Jing Zhao
    via szetszwo)

    HDFS-4244. Support snapshot deletion.  (Jing Zhao via szetszwo)

    HDFS-4245. Include snapshot related operations in TestOfflineEditsViewer.
    (Jing Zhao via szetszwo)

    HDFS-4395. In INodeDirectorySnapshottable's constructor, the passed-in dir
    could be an INodeDirectoryWithSnapshot.  (Jing Zhao via szetszwo)

    HDFS-4397. Fix a bug in INodeDirectoryWithSnapshot.Diff.combinePostDiff(..)
    that it may put the wrong node into the deleted list.  (szetszwo)

    HDFS-4407. Change INodeDirectoryWithSnapshot.Diff.combinePostDiff(..) to
    merge-sort like and keep the postDiff parameter unmodified.  (szetszwo)

    HDFS-4098. Add FileWithSnapshot, INodeFileUnderConstructionWithSnapshot and
    INodeFileUnderConstructionSnapshot for supporting append to snapshotted
    files.  (szetszwo)

    HDFS-4126. Add reading/writing snapshot information to FSImage.
    (Jing Zhao via suresh)

    HDFS-4436. Change INode.recordModification(..) to return only the current
    inode and remove the updateCircularList parameter from some methods in
    INodeDirectoryWithSnapshot.Diff.  (szetszwo)

    HDFS-4429. When the latest snapshot exists, INodeFileUnderConstruction
    should be replaced with INodeFileWithSnapshot but not INodeFile.
    (Jing Zhao via szetszwo)

    HDFS-4441. Move INodeDirectoryWithSnapshot.Diff and the related classes to a
    package.  (szetszwo)

    HDFS-4432. Support INodeFileUnderConstructionWithSnapshot in FSImage
    saving/loading. (Jing Zhao via suresh)

    HDFS-4131. Add capability to namenode to get snapshot diff. (Jing Zhao via
    suresh)

    HDFS-4447. Refactor INodeDirectoryWithSnapshot for supporting general INode
    diff lists.  (szetszwo)

    HDFS-4189. Renames the getMutableXxx methods to getXxx4Write and fix a bug
    that some getExistingPathINodes calls should be getINodesInPath4Write.
    (szetszwo)

    HDFS-4361. When listing snapshottable directories, only return those
    where the user has permission to take snapshots.  (Jing Zhao via szetszwo)

    HDFS-4464. Combine collectSubtreeBlocksAndClear with deleteDiffsForSnapshot
    and rename it to destroySubtreeAndCollectBlocks.  (szetszwo)

    HDFS-4414. Add support for getting snapshot diff from DistributedFileSystem.
    (Jing Zhao via suresh)

    HDFS-4446. Support file snapshots with diff lists.  (szetszwo)

    HDFS-4480. Eliminate the file snapshot circular linked list.  (szetszwo)

    HDFS-4481. Change fsimage to support snapshot file diffs.  (szetszwo)

    HDFS-4500. Refactor snapshot INode methods.  (szetszwo)

    HDFS-4487. Fix snapshot diff report for HDFS-4446.  (Jing Zhao via szetszwo)

    HDFS-4431. Support snapshot in OfflineImageViewer.  (Jing Zhao via szetszwo)

    HDFS-4503. Update computeContentSummary(..), spaceConsumedInTree(..) and
    diskspaceConsumed(..) in INode for snapshot.  (szetszwo)

    HDFS-4499. Fix file/directory/snapshot deletion for file diff.  (Jing Zhao
    via szetszwo)

    HDFS-4524. Update SnapshotManager#snapshottables when loading fsimage.
    (Jing Zhao via szetszwo)

    HDFS-4520. Support listing snapshots under a snapshottable directory using
    ls.  (Jing Zhao via szetszwo)

    HDFS-4514. Add CLI for supporting snapshot rename, diff report, and
    snapshottable directory listing.  (Jing Zhao via szetszwo)

    HDFS-4523. Fix INodeFile replacement, TestQuota and javac errors from trunk
    merge.  (szetszwo)

    HDFS-4507. Update quota verification for snapshots.  (szetszwo)

    HDFS-4545. With snapshots, FSDirectory.unprotectedSetReplication(..) always
    changes file replication but it may or may not changes block replication.
    (szetszwo)

    HDFS-4557. Fix FSDirectory#delete when INode#cleanSubtree returns 0.
    (Jing Zhao via szetszwo)

    HDFS-4579. Annotate snapshot tests. (Arpit Agarwal via suresh)

    HDFS-4574. Move Diff to the util package.  (szetszwo)

    HDFS-4563. Update namespace/diskspace usage after deleting snapshots.
    (Jing Zhao via szetszwo)

    HDFS-4144. Create test for all snapshot-related metrics.
    (Jing Zhao via suresh)

    HDFS-4556. Add snapshotdiff and LsSnapshottableDir tools to hdfs script.
    (Arpit Agarwal via szetszwo)

    HDFS-4534. Add INodeReference in order to support rename with snapshots.
    (szetszwo)

    HDFS-4616. Update the FilesDeleted metric while deleting file/dir in the
    current tree.  (Jing Zhao via szetszwo)

    HDFS-4627. Fix FSImageFormat#Loader NPE and synchronization issues.
    (Jing Zhao via suresh)

    HDFS-4612. Not to use INode.getParent() when generating snapshot diff
    report.  (Jing Zhao via szetszwo)

    HDFS-4636. Update quota usage when deleting files/dirs that were created
    after taking the latest snapshot. (Jing Zhao via szetszwo)

    HDFS-4648. For snapshot deletion, when merging the diff from to-delete
    snapshot to the prior snapshot, make sure files/directories created after
    the prior snapshot get deleted. (Jing Zhao via szetszwo)

    HDFS-4637. INodeDirectory#replaceSelf4Quota may incorrectly convert a newly
    created directory to an INodeDirectoryWithSnapshot. (Jing Zhao via szetszwo)

    HDFS-4611. Update FSImage for INodeReference.  (szetszwo)

    HDFS-4647. Rename should call setLocalName after an inode is removed from
    snapshots.  (Arpit Agarwal via szetszwo)

    HDFS-4684. Use INode id for image serialization when writing INodeReference.
    (szetszwo)

    HDFS-4675. Fix rename across snapshottable directories.  (Jing Zhao via
    szetszwo)

    HDFS-4692. Use timestamp as default snapshot names.  (szetszwo)

    HDFS-4666. Define ".snapshot" as a reserved inode name so that users cannot
    create a file/directory with ".snapshot" as the name.  If ".snapshot" is
    used in a previous version of HDFS, it must be renamed before upgrade;
    otherwise, upgrade will fail.  (szetszwo)

    HDFS-4700. Fix the undo section of rename with snapshots.  (Jing Zhao via
    szetszwo)

    HDFS-4529. Disallow concat when one of the src files is in some snapshot.
    (szetszwo)

    HDFS-4550. Refactor INodeDirectory.INodesInPath to a standalone class.
    (szetszwo)

    HDFS-4707. Add snapshot methods to FilterFileSystem and fix findbugs
    warnings.  (szetszwo)

    HDFS-4706. Do not replace root inode for disallowSnapshot.  (szetszwo)

    HDFS-4717. Change the path parameter type of the snapshot methods in
    HdfsAdmin from String to Path.  (szetszwo)

    HDFS-4708. Add snapshot user documentation.  (szetszwo)

    HDFS-4726. Fix test failures after merging the INodeId-INode mapping
    from trunk.  (Jing Zhao via szetszwo)

    HDFS-4727. Update inodeMap after deleting files/directories/snapshots.
    (Jing Zhao via szetszwo)

    HDFS-4719. Remove AbstractINodeDiff.Factory and move its methods to
    AbstractINodeDiffList.  (Arpit Agarwal via szetszwo)

    HDFS-4735. DisallowSnapshot throws IllegalStateException for nested
    snapshottable directories.  (Jing Zhao via szetszwo)

    HDFS-4738. Changes AbstractINodeDiff to implement Comparable<Integer>, and
    fix javadoc and other warnings.  (szetszwo)

    HDFS-4686. Update quota computation for rename and INodeReference.
    (Jing Zhao via szetszwo)

    HDFS-4729. Fix OfflineImageViewer and permission checking for snapshot
    operations.  (Jing Zhao via szetszwo)

    HDFS-4749. Use INodeId to identify the corresponding directory node in
    FSImage saving/loading.  (Jing Zhao via szetszwo)

    HDFS-4742. Fix appending to a renamed file with snapshot.  (Jing Zhao via
    szetszwo)

    HDFS-4755. Fix AccessControlException message and moves "implements
    LinkedElement" from INode to INodeWithAdditionalFields.  (szetszwo)

    HDFS-4650. Fix a bug in FSDirectory and add more unit tests for rename with
    existence of snapshottable directories and snapshots.  (Jing Zhao via
    szetszwo)

    HDFS-4650. When passing two non-existing snapshot names to snapshotDiff, it
    returns success if the names are the same.  (Jing Zhao via szetszwo)

    HDFS-4767. If a directory is snapshottable, do not replace it when clearing
    quota.  (Jing Zhao via szetszwo)

    HDFS-4578.  Restrict snapshot IDs to 24-bit wide.  (Arpit Agarwal via
    szetszwo)

    HDFS-4773. Fix bugs in quota usage computation and OfflineImageViewer.
    (Jing Zhao via szetszwo)

    HDFS-4760. Update inodeMap after node replacement.  (Jing Zhao via szetszwo)

    HDFS-4758. Disallow nested snapshottable directories and unwrap
    RemoteException.  (szetszwo)

    HDFS-4781. Fix a NullPointerException when listing .snapshot under
    a non-existing directory.  (szetszwo)

    HDFS-4791. Update and fix deletion of reference inode.  (Jing Zhao via
    szetszwo)

    HDFS-4798. Update computeContentSummary() for the reference nodes in
    snapshots.  (szetszwo)

    HDFS-4800. Fix INodeDirectoryWithSnapshot#cleanDeletedINode.  (Jing Zhao via
    szetszwo)

    HDFS-4801. lsSnapshottableDir throws IllegalArgumentException when root is
    snapshottable.  (Jing Zhao via szetszwo)

    HDFS-4802. Disallowing snapshot on / twice should throw SnapshotException
    but not IllegalStateException.  (Jing Zhao via szetszwo)

    HDFS-4806. In INodeDirectoryWithSnapshot, use isInLatestSnapshot() to
    determine if an added/removed child should be recorded in the snapshot diff.
    (Jing Zhao via szetszwo)

    HDFS-4809. When a QuotaExceededException is thrown during rename, the quota
    usage should be subtracted back.  (Jing Zhao via szetszwo)

    HDFS-4842. Identify the correct prior snapshot when deleting a 
    snapshot under a renamed subtree. (jing9)

    HDFS-4846. Clean up snapshot CLI commands output stacktrace for invalid
    arguments. (Jing Zhao via brandonli)

    HDFS-4857. Snapshot.Root and AbstractINodeDiff#snapshotINode should not be 
    put into INodeMap when loading FSImage. (jing9)

    HDFS-4863. The root directory should be added to the snapshottable 
    directory list while loading fsimage. (jing9)

    HDFS-4848. copyFromLocal and renaming a file to ".snapshot" should output 
    that ".snapshot" is a reserved name. (Jing Zhao via brandonli)

    HDFS-4826. TestNestedSnapshots times out due to repeated slow edit log
    flushes when running on virtualized disk.  (Chris Nauroth via szetszwo)

    HDFS-4876. Fix the javadoc of FileWithSnapshot and move FileDiffList to
    FileWithSnapshot.  (szetszwo)

    HDFS-4850. Fix OfflineImageViewer to work on fsimages with empty files or 
    snapshots. (jing9) 

    HDFS-4877. Snapshot: fix the scenario where a directory is renamed under 
    its prior descendant. (jing9)

    HDFS-4873. callGetBlockLocations returns incorrect number of blocks for 
    snapshotted files. (jing9)

    HDFS-4819. Update Snapshot doc to clarify that nested snapshots are not
    allowed.  (szetszwo)

    HDFS-4902. DFSClient.getSnapshotDiffReport should use string path rather 
    than o.a.h.fs.Path. (Binglin Chang via jing9) 

    HDFS-4875. Add a test for testing snapshot file length. 
    (Arpit Agarwal via jing9)

    HDFS-4841. FsShell commands using secure webhfds fail ClientFinalizer 
    shutdown hook. (rkanter via tucu)

    HDFS-4951. FsShell commands using secure httpfs throw exceptions due 
    to missing TokenRenewer. (rknater via tucu)

    HDFS-4969. WebhdfsFileSystem expects non-standard WEBHDFS Json element. 
    (rkanter via tucu)

    HDFS-4797. BlockScanInfo does not override equals(..) and hashCode()
    consistently.  (szetszwo)

    HDFS-4978. Make disallowSnapshot idempotent. (jing9)

    HDFS-5005. Move SnapshotException and SnapshotAccessControlException 
    to o.a.h.hdfs.protocol. (jing9)

    HDFS-4982. JournalNode should relogin from keytab before fetching logs
    from other JNs (todd)

Release 2.0.6-alpha - 08/22/2013

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

  OPTIMIZATIONS

Release 2.0.5-alpha - 06/06/2013

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

  OPTIMIZATIONS

  BUG FIXES

Release 2.0.4-alpha - 2013-04-25

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

  OPTIMIZATIONS

  BUG FIXES

Release 2.0.3-alpha - 2013-02-06

  INCOMPATIBLE CHANGES

    HDFS-4122. Cleanup HDFS logs and reduce the size of logged messages.
    (suresh)

    HDFS-4362. GetDelegationTokenResponseProto does not handle null token.
    (suresh)

    HDFS-4367. GetDataEncryptionKeyResponseProto does not handle null
    response. (suresh)

    HDFS-4364. GetLinkTargetResponseProto does not handle null path. (suresh)

    HDFS-4369. GetBlockKeysResponseProto does not handle null response.
    (suresh)

    HDFS-4451. hdfs balancer command returns exit code 1 on success instead
    of 0. (Joshua Blatt via suresh)

    HDFS-4350. Make enabling of stale marking on read and write paths
    independent. (Andrew Wang via suresh)


  NEW FEATURES

    HDFS-2656. Add libwebhdfs, a pure C client based on WebHDFS.
    (Jaimin D Jetly and Jing Zhao via szetszwo)

    HDFS-3912. Detect and avoid stale datanodes for writes.
    (Jing Zhao via suresh)

    HDFS-4059. Add number of stale DataNodes to metrics. (Jing Zhao via suresh)

    HDFS-4155. libhdfs implementation of hsync API (Liang Xie via todd)

    HDFS-4213. Add an API to hsync for updating the last block length at the
    namenode. (Jing Zhao via szetszwo)

    HDFS-3077. Implement QuorumJournalManager, a distributed mechanism for
    reliably storing HDFS edit logs. See dedicated section below for breakdown
    of subtasks.

  IMPROVEMENTS
  
    HDFS-3925. Prettify PipelineAck#toString() for printing to a log
    (Andrew Wang via todd)

    HDFS-3939. NN RPC address cleanup. (eli)

    HDFS-3373. Change DFSClient input stream socket cache to global static and
    add a thread to cleanup expired cache entries. (John George via szetszwo)

    HDFS-3896. Add descriptions for dfs.namenode.rpc-address and
    dfs.namenode.servicerpc-address to hdfs-default.xml. (Jeff Lord via atm)

    HDFS-3996. Add debug log removed in HDFS-3873 back. (eli)

    HDFS-3916. libwebhdfs (C client) code cleanups.
    (Colin Patrick McCabe via eli)

    HDFS-3813. Log error message if security and WebHDFS are enabled but
    principal/keytab are not configured. (Stephen Chu via atm)

    HDFS-3483. Better error message when hdfs fsck is run against a ViewFS
    config. (Stephen Fritz via atm)

    HDFS-3682. MiniDFSCluster#init should provide more info when it fails.
    (todd via eli)

    HDFS-4008. TestBalancerWithEncryptedTransfer needs a timeout. (eli)

    HDFS-4007. Rehabilitate bit-rotted unit tests under
    hadoop-hdfs-project/hadoop-hdfs/src/test/unit/ 
    (Colin Patrick McCabe via todd)

    HDFS-4041. Hadoop HDFS Maven protoc calls must not depend on external
    sh script. (Chris Nauroth via suresh)

    HADOOP-8911. CRLF characters in source and text files.
    (Raja Aluri via suresh)

    HDFS-4037. Rename the getReplication() method in BlockCollection to
    getBlockReplication(). (szetszwo)

    HDFS-4036. Remove "throws UnresolvedLinkException" from
    FSDirectory.unprotectedAddFile(..). (Jing Zhao via szetszwo)

    HDFS-2946. HA: Put a cap on the number of completed edits files retained
    by the NN. (atm)

    HDFS-4029. GenerationStamp should use an AtomicLong. (eli)

    HDFS-4068. DatanodeID and DatanodeInfo member should be private. (eli)

    HDFS-4073. Two minor improvements to FSDirectory.  (Jing Zhao via szetszwo)

    HDFS-4074. Remove the unused default constructor from INode.  (Brandon Li
    via szetszwo)

    HDFS-4088. Remove "throws QuotaExceededException" from an
    INodeDirectoryWithQuota constructor. (szetszwo)

    HDFS-4099. Clean up replication code and add more javadoc. (szetszwo)

    HDFS-4107. Add utility methods for casting INode to INodeFile and
    INodeFileUnderConstruction. (szetszwo)

    HDFS-4112. A few improvements on INodeDirectory include adding a utility
    method for casting; avoiding creation of new empty lists; cleaning up 
    some code and rewriting some javadoc. (szetszwo)

    HDFS-4121. Add namespace declarations in hdfs .proto files for languages 
    other than java. (Binglin Chang via suresh)

    HDFS-3573. Supply NamespaceInfo when instantiating JournalManagers. 
    (todd and ivank via umamahesh)

    HDFS-3695. Genericize format() to non-file JournalManagers. 
    (todd via umamahesh)

    HDFS-3789. JournalManager#format() should be able to throw IOException. 
    (Ivan Kelly via umamahesh)

    HDFS-3809. Make BKJM use protobufs for all serialization with ZK. 
    (Ivan Kelly via umamhesh)

    HDFS-3916. libwebhdfs testing code cleanup. (Jing Zhao via suresh)

    HDFS-4143. Change blocks to private in INodeFile and renames isLink() to
    isSymlink() in INode. (szetszwo)

    HDFS-4046. Rename ChecksumTypeProto enum NULL since it is illegal in
    C/C++. (Binglin Chang via suresh)

    HDFS-4048. Use ERROR instead of INFO for volume failure logs.
    (Stephen Chu via eli)

    HDFS-1322. Document umask in DistributedFileSystem#mkdirs javadocs.
    (Colin Patrick McCabe via eli)

    HDFS-4038. Override toString() for BookKeeperEditLogInputStream.
    (Vinay via umamahesh)

    HDFS-4214. OfflineEditsViewer should print out the offset at which it
    encountered an error. (Colin Patrick McCabe via atm)

    HDFS-4199. Provide test for HdfsVolumeId. (Ivan A. Veselovsky via atm)

    HDFS-3049. During the normal NN startup process, fall back on a different
    edit log if we see one that is corrupt (Colin Patrick McCabe via todd)

    HDFS-3571. Allow EditLogFileInputStream to read from a remote URL (todd)

    HDFS-4110. Refine a log printed in JNStorage. (Liang Xie via suresh)

    HDFS-4153. Add START_MSG/SHUTDOWN_MSG for JournalNode. (liang xie via atm)

    HDFS-3935. Add JournalNode to the start/stop scripts (Andy Isaacson via todd)

    HDFS-4268. Remove redundant enum NNHAStatusHeartbeat.State. (shv)

    HDFS-3680. Allow customized audit logging in HDFS FSNamesystem. (Marcelo
    Vanzin via atm)

    HDFS-4130. BKJM: The reading for editlog at NN starting using bkjm is not efficient.
    (Han Xiao via umamahesh)

    HDFS-4326. bump up Tomcat version for HttpFS to 6.0.36. (tucu via acmurthy)

    HDFS-4270. Introduce soft and hard limits for max replication so that
    replications of the highest priority are allowed to choose a source datanode
    that has reached its soft limit but not the hard limit.  (Derek Dagit via
    szetszwo)

    HADOOP-9173. Add security token protobuf definition to common and
    use it in hdfs. (suresh)

    HDFS-4030. BlockManager excessBlocksCount and
    postponedMisreplicatedBlocksCount should be AtomicLongs. (eli)

    HDFS-4031. Update findbugsExcludeFile.xml to include findbugs 2
    exclusions. (eli)

    HDFS-4033. Miscellaneous findbugs 2 fixes. (eli)

    HDFS-4034. Remove redundant null checks. (eli)

    HDFS-4035. LightWeightGSet and LightWeightHashSet increment a
    volatile without synchronization. (eli)
    
    HDFS-4032. Specify the charset explicitly rather than rely on the
    default. (eli)

    HDFS-4363. Combine PBHelper and HdfsProtoUtil and remove redundant
    methods. (suresh)

    HDFS-4377. Some trivial DN comment cleanup. (eli)

    HDFS-4381. Document fsimage format details in FSImageFormat class javadoc.
    (Jing Zhao via suresh)

    HDFS-4375. Use token request messages defined in hadoop common.
    (suresh)

    HDFS-4392. Use NetUtils#getFreeSocketPort in MiniDFSCluster.
    (Andrew Purtell via suresh)

    HDFS-4393. Make empty request and responses in protocol translators can be
    static final members. (Brandon Li via suresh)

    HDFS-4403. DFSClient can infer checksum type when not provided by reading
    first byte (todd)

    HDFS-4259. Improve pipeline DN replacement failure message (harsh)

    HDFS-3598. WebHDFS support for file concat. (Plamen Jeliazkov via shv)

    HDFS-4456. Add concat to HttpFS and WebHDFS REST API docs. (plamenj2003 via tucu)

    HDFS-3131. Improve TestStorageRestore. (Brandon Li via atm)

  OPTIMIZATIONS

    HDFS-3429. DataNode reads checksums even if client does not need them (todd)

  BUG FIXES

    HDFS-3919. MiniDFSCluster:waitClusterUp can hang forever.
    (Andy Isaacson via eli)

    HDFS-3924. Multi-byte id in HdfsVolumeId. (Andrew Wang via atm)

    HDFS-3936. MiniDFSCluster shutdown races with BlocksMap usage. (eli)

    HDFS-3951. datanode web ui does not work over HTTPS when datanode is started in secure mode. (tucu)

    HDFS-3949. NameNodeRpcServer#join should join on both client and
    server RPC servers. (eli)

    HDFS-3932. NameNode Web UI broken if the rpc-address is set to the wildcard.
    (Colin Patrick McCabe via eli)

    HDFS-3931. TestDatanodeBlockScanner#testBlockCorruptionPolicy2 is broken.
    (Andy Isaacson via eli)

    HDFS-3964. Make NN log of fs.defaultFS debug rather than info. (eli)

    HDFS-3992. Method org.apache.hadoop.hdfs.TestHftpFileSystem.tearDown()
    sometimes throws NPEs. (Ivan A. Veselovsky via atm)

    HDFS-3753. Tests don't run with native libraries.
    (Colin Patrick McCabe via eli)

    HDFS-4000. TestParallelLocalRead fails with "input ByteBuffers
    must be direct buffers". (Colin Patrick McCabe via eli)

    HDFS-3999. HttpFS OPEN operation expects len parameter, it should be length. (tucu)

    HDFS-4006. TestCheckpoint#testSecondaryHasVeryOutOfDateImage
    occasionally fails due to unexpected exit. (todd via eli)

    HDFS-4018. testMiniDFSClusterWithMultipleNN is missing some
    cluster cleanup. (eli)

    HDFS-4020. TestRBWBlockInvalidation may time out. (eli)

    HDFS-4021. Misleading error message when resources are low on the NameNode.
    (Christopher Conner via atm)

    HDFS-4044. Duplicate ChecksumType definition in HDFS .proto files.
    (Binglin Chang via suresh)

    HDFS-4049. Fix hflush performance regression due to nagling delays
    (todd)

    HDFS-3678. Edit log files are never being purged from 2NN. (atm)

    HDFS-4058. DirectoryScanner may fail with IOOB if the directory
    scanning threads return out of volume order. (eli)

    HDFS-3985. Add timeouts to TestMulitipleNNDataBlockScanner. (todd via eli)

    HDFS-4061. TestBalancer and TestUnderReplicatedBlocks need timeouts. (eli)

    HDFS-3997. OfflineImageViewer incorrectly passes value of imageVersion when
    visiting IS_COMPRESSED element. (Mithun Radhakrishnan via atm)

    HDFS-4055. TestAuditLogs is flaky. (Binglin Chang via eli)

    HDFS-4072. On file deletion remove corresponding blocks pending
    replications. (Jing Zhao via suresh)

    HDFS-4022. Replication not happening for appended block.
    (Vinay via umamahesh)

    HDFS-3948. Do not use hflush in TestWebHDFS.testNamenodeRestart() since the
    out stream returned by WebHdfsFileSystem does not support it. (Jing Zhao
    via szetszwo)

    HDFS-3616. Fix a ConcurrentModificationException bug that BP actor threads
    may not be shutdown properly in DataNode.  (Jing Zhao via szetszwo)

    HDFS-4127. Log message is not correct in case of short of replica.
    (Junping Du via suresh)

    HADOOP-8994. TestDFSShell creates file named "noFileHere", making further
    tests hard to understand (Andy Isaacson via daryn)

    HDFS-3804.  TestHftpFileSystem fails intermittently with JDK7
    (Trevor Robinson via daryn)

    HDFS-4132. When libwebhdfs is not enabled, nativeMiniDfsClient frees
    uninitialized memory (Colin Patrick McCabe via todd)

    HDFS-1331. dfs -test should work like /bin/test (Andy Isaacson via daryn)

    HDFS-3979. For hsync, datanode should wait for the local sync to complete
    before sending ack. (Lars Hofhansl via szetszwo)

    HDFS-3810. Implement format() for BKJM (Ivan Kelly via umamahesh)

    HDFS-3625. Fix TestBackupNode by properly initializing edit log during
    startup. (Junping Du via todd)

    HDFS-4138. BackupNode startup fails due to uninitialized edit log.
    (Kihwal Lee via shv)

    HDFS-4162. Some malformed and unquoted HTML strings are returned from 
    datanode web ui. (Darek Dagit via suresh)

    HDFS-4164. fuse_dfs: add -lrt to the compiler command line on Linux.
    (Colin Patrick McCabe via eli)

    HDFS-3921. NN will prematurely consider blocks missing when entering active
    state while still in safe mode. (atm)

    HDFS-4106. BPServiceActor#lastHeartbeat, lastBlockReport and
    lastDeletedReport should be volatile. (Jing Zhao via suresh)

    HDFS-4139. fuse-dfs RO mode still allows file truncation.
    (Colin Patrick McCabe via eli)    

    HDFS-4104. dfs -test -d prints inappropriate error on nonexistent directory
    (Andy Isaacson via daryn)

    HDFS-3623. BKJM: zkLatchWaitTimeout hard coded to 6000. Make use of ZKSessionTimeout instead.
    (umamahesh)

    HDFS-4100. Fix all findbug security warings. (Liang Xie via eli)

    HDFS-3507. DFS#isInSafeMode needs to execute only on Active NameNode.
    (Vinay via atm)

    HDFS-4105. The SPNEGO user for secondary namenode should use the web
    keytab. (Arpit Gupta via jitendra)

    HDFS-4156. Seeking to a negative position should throw an IOE.
    (Eli Reisman via eli)

    HDFS-4171. WebHDFS and HttpFs should accept only valid Unix user 
    names. (tucu)

    HDFS-4178. Shell scripts should not close stderr (Andy Isaacson via daryn)

    HDFS-4179. BackupNode: allow reads, fix checkpointing, safeMode. (shv)

    HDFS-4216. Do not ignore QuotaExceededException when adding symlinks.
    (szetszwo)

    HDFS-4242. Map.Entry is incorrectly used in LeaseManager since the behavior
    of it is undefined after the iteration or modifications of the map.
    (szetszwo)

    HDFS-4231. BackupNode: Introduce BackupState. (shv)

    HDFS-4238. Standby namenode should not do purging of shared
    storage edits. (todd)

    HDFS-4282. TestEditLog.testFuzzSequences FAILED in all pre-commit test
    (todd)

    HDFS-4236. Remove artificial limit on username length introduced in
    HDFS-4171. (tucu via suresh)

    HDFS-4279. NameNode does not initialize generic conf keys when started
    with -recover. (Colin Patrick McCabe via atm)

    HDFS-4291. edit log unit tests leave stray test_edit_log_file around
    (Colin Patrick McCabe via todd)

    HDFS-4292. Sanity check not correct in RemoteBlockReader2.newBlockReader
    (Binglin Chang via todd)

    HDFS-4295. Using port 1023 should be valid when starting Secure DataNode
    (Stephen Chu via todd)

    HDFS-4294. Backwards compatibility is not maintained for TestVolumeId.
    (Ivan A. Veselovsky and Robert Parker via atm)

    HDFS-2264. NamenodeProtocol has the wrong value for clientPrincipal in
    KerberosInfo annotation. (atm)

    HDFS-4307. SocketCache should use monotonic time. (Colin Patrick McCabe
    via atm)

    HDFS-4315. DNs with multiple BPs can have BPOfferServices fail to start
    due to unsynchronized map access. (atm)

    HDFS-4140. fuse-dfs handles open(O_TRUNC) poorly. (Colin Patrick McCabe
    via atm)

    HDFS-4308. addBlock() should persist file blocks once.
    (Plamen Jeliazkov via shv)

    HDFS-4347. Avoid infinite waiting checkpoint to complete in TestBackupNode.
    (Plamen Jeliazkov via shv)

    HDFS-4349. Add test for reading files from BackupNode. (shv)

    HDFS-4302. Fix fatal exception when starting NameNode with DEBUG logs
    (Eugene Koontz via todd)

    HDFS-3970. Fix bug causing rollback of HDFS upgrade to result in bad
    VERSION file. (Vinay and Andrew Wang via atm)

    HDFS-4306. PBHelper.convertLocatedBlock miss convert BlockToken. (Binglin
    Chang via atm)

    HDFS-4384. test_libhdfs_threaded gets SEGV if JNIEnv cannot be
    initialized. (Colin Patrick McCabe via eli)

    HDFS-4328. TestLargeBlock#testLargeBlockSize is timing out. (Chris Nauroth
    via atm)

    HDFS-4274. BlockPoolSliceScanner does not close verification log during
    shutdown. (Chris Nauroth via suresh)

    HDFS-1245. Pluggable block id generation. (shv)

    HDFS-4415. HostnameFilter should handle hostname resolution failures and
    continue processing. (Robert Kanter via atm)

    HDFS-4359. Slow RPC responses from NN can prevent metrics collection on
    DNs. (liang xie via atm)

    HDFS-4444. Add space between total transaction time and number of
    transactions in FSEditLog#printStatistics. (Stephen Chu via suresh)

    HDFS-4428. FsDatasetImpl should disclose what the error is when a rename
    fails. (Colin Patrick McCabe via atm)

    HDFS-4452. getAdditionalBlock() can create multiple blocks if the client
    times out and retries. (shv)

    HDFS-4445. All BKJM ledgers are not checked while tailing, So failover will fail.
    (Vinay via umamahesh)

    HDFS-4462. 2NN will fail to checkpoint after an HDFS upgrade from a
    pre-federation version of HDFS. (atm)

    HDFS-4404. Create file failure when the machine of first attempted NameNode
    is down. (Todd Lipcon via atm)

    HDFS-4344. dfshealth.jsp throws NumberFormatException when
    dfs.hosts/dfs.hosts.exclude includes port number. (Andy Isaacson via atm)

    HDFS-4468.  Use the new StringUtils methods added by HADOOP-9252 and fix
    TestHDFSCLI and TestQuota. (szetszwo)

    HDFS-4458. In DFSUtil.getNameServiceUris(..), convert default fs URI using
    NetUtils.createSocketAddr(..) for being consistent with other addresses.
    (Binglin Chang via szetszwo)

  BREAKDOWN OF HDFS-3077 SUBTASKS

    HDFS-3077. Quorum-based protocol for reading and writing edit logs.
    (todd, Brandon Li, and Hari Mankude via todd)
    
    HDFS-3694. Fix getEditLogManifest to fetch httpPort if necessary (todd)
    
    HDFS-3692. Support purgeEditLogs() call to remotely purge logs on JNs
    (todd)
    
    HDFS-3693. JNStorage should read its storage info even before a writer
    becomes active (todd)
    
    HDFS-3725. Fix QJM startup when individual JNs have gaps (todd)
    
    HDFS-3741. Exhaustive failure injection test for skipped RPCs (todd)
    
    HDFS-3773. TestNNWithQJM fails after HDFS-3741. (atm)
    
    HDFS-3793. Implement genericized format() in QJM (todd)
    
    HDFS-3795. QJM: validate journal dir at startup (todd)
    
    HDFS-3798. Avoid throwing NPE when finalizeSegment() is called on invalid
    segment (todd)
    
    HDFS-3799. QJM: handle empty log segments during recovery (todd)
    
    HDFS-3797. QJM: add segment txid as a parameter to journal() RPC (todd)
    
    HDFS-3800. improvements to QJM fault testing (todd)
    
    HDFS-3823. QJM: TestQJMWithFaults fails occasionally because of missed
    setting of HTTP port. (todd and atm)
    
    HDFS-3826. QJM: Some trivial logging / exception text improvements. (todd
    and atm)
    
    HDFS-3839. QJM: hadoop-daemon.sh should be updated to accept "journalnode"
    (eli)
    
    HDFS-3845. Fixes for edge cases in QJM recovery protocol (todd)
    
    HDFS-3877. QJM: Provide defaults for dfs.journalnode.*address (eli)
    
    HDFS-3863. Track last "committed" txid in QJM (todd)
    
    HDFS-3869. Expose non-file journal manager details in web UI (todd)
    
    HDFS-3884. Journal format() should reset cached values (todd)
    
    HDFS-3870. Add metrics to JournalNode (todd)
    
    HDFS-3891. Make selectInputStreams throw IOE instead of RTE (todd)
    
    HDFS-3726. If a logger misses an RPC, don't retry that logger until next
    segment (todd)
    
    HDFS-3893. QJM: Make QJM work with security enabled. (atm)
    
    HDFS-3897. QJM: TestBlockToken fails after HDFS-3893. (atm)
    
    HDFS-3898. QJM: enable TCP_NODELAY for IPC (todd)
    
    HDFS-3885. QJM: optimize log sync when JN is lagging behind (todd)
    
    HDFS-3900. QJM: avoid validating log segments on log rolls (todd)
    
    HDFS-3901. QJM: send 'heartbeat' messages to JNs even when they are
    out-of-sync (todd)
    
    HDFS-3899. QJM: Add client-side metrics (todd)
    
    HDFS-3914. QJM: acceptRecovery should abort current segment (todd)
    
    HDFS-3915. QJM: Failover fails with auth error in secure cluster (todd)
    
    HDFS-3906. QJM: quorum timeout on failover with large log segment (todd)
    
    HDFS-3840. JournalNodes log JournalNotFormattedException backtrace error
    before being formatted (todd)
    
    HDFS-3894. QJM: testRecoverAfterDoubleFailures can be flaky due to IPC
    client caching (todd)
    
    HDFS-3926. QJM: Add user documentation for QJM. (atm)
    
    HDFS-3943. QJM: remove currently-unused md5sum field (todd)
    
    HDFS-3950. QJM: misc TODO cleanup, improved log messages, etc. (todd)
    
    HDFS-3955. QJM: Make acceptRecovery() atomic. (todd)
    
    HDFS-3956. QJM: purge temporary files when no longer within retention
    period (todd)
    
    HDFS-4004. TestJournalNode#testJournal fails because of test case execution
    order (Chao Shi via todd)
    
    HDFS-4017. Unclosed FileInputStream in GetJournalEditServlet
    (Chao Shi via todd)

    HDFS-4351. In BlockPlacementPolicyDefault.chooseTarget(..), numOfReplicas
    needs to be updated when avoiding stale nodes.  (Andrew Wang via szetszwo)

    HDFS-2908. Add apache license header for StorageReport.java. (Brandon Li
    via tgraves)

    HDFS-4399. Fix RAT warnings by excluding images sub-dir in docs. (Thomas
    Graves via acmurthy) 

Release 2.0.2-alpha - 2012-09-07 

  INCOMPATIBLE CHANGES

    HDFS-3446. HostsFileReader silently ignores bad includes/excludes
    (Matthew Jacobs via todd)

    HDFS-3755. Creating an already-open-for-write file with overwrite=true fails
    (todd)

  NEW FEATURES

    HDFS-744. Support hsync in HDFS. (Lars Hofhansl via szetszwo)

    HDFS-3042. Automatic failover support for NameNode HA (todd)
    (see dedicated section below for breakdown of subtasks)

    HDFS-3518. Add a utility method HdfsUtils.isHealthy(uri) for checking if
    the given HDFS is healthy. (szetszwo)

    HDFS-3113. httpfs does not support delegation tokens. (tucu)

    HDFS-3513. HttpFS should cache filesystems. (tucu)

    HDFS-3637. Add support for encrypting the DataTransferProtocol. (atm)

    HDFS-3150. Add option for clients to contact DNs via hostname. (eli)

    HDFS-2793. Add an admin command to trigger an edit log roll. (todd)

    HDFS-3703. Datanodes are marked stale if heartbeat is not received in
    configured timeout and are selected as the last location to read from.
    (Jing Zhao via suresh)
    
  IMPROVEMENTS

    HDFS-3040. TestMulitipleNNDataBlockScanner is misspelled. (Madhukara Phatak
    via atm)

    HDFS-3390. DFSAdmin should print full stack traces of errors when DEBUG
    logging is enabled. (atm)

    HDFS-3341. Change minimum RPC versions to respective SNAPSHOTs instead of
    final releases. (todd)

    HDFS-3369. Rename {get|set|add}INode(..) methods in BlockManager and
    BlocksMap to {get|set|add}BlockCollection(..).  (John George via szetszwo)

    HDFS-3134. harden edit log loader against malformed or malicious input.
    (Colin Patrick McCabe via eli)

    HDFS-3230. Cleanup DatanodeID creation in the tests. (eli)

    HDFS-3401. Cleanup DatanodeDescriptor creation in the tests. (eli)

    HDFS-3400. DNs should be able start with jsvc even if security is disabled.
    (atm via eli)

    HDFS-3404. Make putImage in GetImageServlet infer remote address to fetch
    from request. (atm)

    HDFS-3335. check for edit log corruption at the end of the log
    (Colin Patrick McCabe via todd)

    HDFS-3417. Rename BalancerDatanode#getName to getDisplayName to be
    consistent with Datanode. (eli)

    HDFS-3416. Cleanup DatanodeID and DatanodeRegistration
    constructors used by testing. (eli)

    HDFS-3419. Cleanup LocatedBlock. (eli)

    HDFS-3440. More effectively limit stream memory consumption when reading
    corrupt edit logs (Colin Patrick McCabe via todd)

    HDFS-3438. BootstrapStandby should not require a rollEdits on active node
    (todd)

    HDFS-2885. Remove "federation" from the nameservice config options.
    (Tsz Wo (Nicholas) Sze via eli)

    HDFS-3394. Do not use generic in INodeFile.getLastBlock(): the run-time
    ClassCastException check is useless since generic type information is only
    available in compile-time.  (szetszwo)

    HDFS-3454. Balancer unconditionally logs InterruptedException at
    INFO level on shutdown if security is enabled. (eli)

    HDFS-1013. Miscellaneous improvements to HTML markup for web UIs
    (Eugene Koontz via todd)

    HDFS-3052. Change INodeFile and INodeFileUnderConstruction to package
    private.  (szetszwo)

    HDFS-3520. Add transfer rate logging to TransferFsImage. (eli)

    HDFS-3504. Support configurable retry policy in DFSClient for RPC
    connections and RPC calls, and add MultipleLinearRandomRetry, a new retry
    policy.  (szetszwo)

    HDFS-3372. offlineEditsViewer should be able to read a binary
    edits file with recovery mode. (Colin Patrick McCabe via eli)

    HDFS-3516. Check content-type in WebHdfsFileSystem.  (szetszwo)

    HDFS-3535. Audit logging should log denied accesses. (Andy Isaacson via eli)

    HDFS-3481. Refactor HttpFS handling of JAX-RS query string parameters (tucu)

    HDFS-3572. Cleanup code which inits SPNEGO in HttpServer (todd)

    HDFS-3475. Make the replication monitor multipliers configurable.
    (harsh via eli)

    HDFS-3343. Improve metrics for DN read latency (Andrew Wang via todd)

    HDFS-3170. Add more useful metrics for write latency (Matthew Jacobs via
    todd)

    HDFS-3604. Add dfs.webhdfs.enabled to hdfs-default.xml. (eli)

    HDFS-2988. Improve error message when storage directory lock fails
    (Miomir Boljanovic via harsh)

    HDFS-2391. Newly set BalancerBandwidth value is not displayed anywhere.
    (harsh)

    HDFS-3067. NPE in DFSInputStream.readBuffer if read is repeated on
    corrupted block. (Henry Robinson via atm)

    HDFS-3555. idle client socket triggers DN ERROR log
    (should be INFO or DEBUG). (Andy Isaacson via harsh)

    HDFS-3568. fuse_dfs: add support for security. (Colin McCabe via atm)

    HDFS-3629. Fix the typo in the error message about inconsistent
    storage layout version. (Brandon Li via harsh)

    HDFS-3613. GSet prints some INFO level values, which aren't
    really very useful to all (Andrew Wang via harsh)

    HDFS-3611. NameNode prints unnecessary WARNs about edit log normally skipping 
    a few bytes. (Colin Patrick McCabe via harsh)

    HDFS-3582. Hook daemon process exit for testing. (eli)

    HDFS-3641. Move server Util time methods to common and use now
    instead of System#currentTimeMillis. (eli)

    HDFS-3633. libhdfs: hdfsDelete should pass JNI_FALSE or JNI_TRUE.
    (Colin Patrick McCabe via eli)

    HDFS-799. libhdfs must call DetachCurrentThread when a thread is destroyed.
    (Colin Patrick McCabe via eli)

    HDFS-3306. fuse_dfs: don't lock release operations.
    (Colin Patrick McCabe via eli)

    HDFS-3612. Single namenode image directory config warning can
    be improved. (Andy Isaacson via harsh)

    HDFS-3606. libhdfs: create self-contained unit test.
    (Colin Patrick McCabe via eli)

    HDFS-3539. libhdfs code cleanups. (Colin Patrick McCabe via eli)

    HDFS-3610. fuse_dfs: Provide a way to use the default (configured) NN URI.
    (Colin Patrick McCabe via eli)

    HDFS-3663. MiniDFSCluster should capture the code path that led to
    the first ExitException. (eli)

    HDFS-3659. Add missing @Override to methods across the hadoop-hdfs
    project. (Brandon Li via harsh)

    HDFS-3537. Move libhdfs and fuse-dfs source to native subdirectories.
    (Colin Patrick McCabe via eli)

    HDFS-3665. Add a test for renaming across file systems via a symlink. (eli)

    HDFS-3666. Plumb more exception messages to terminate. (eli)

    HDFS-3673. libhdfs: fix some compiler warnings. (Colin Patrick McCabe via eli)

    HDFS-3675. libhdfs: follow documented return codes. (Colin Patrick McCabe via eli)

    HDFS-1249. With fuse-dfs, chown which only has owner (or only group)
    argument fails with Input/output error. (Colin Patrick McCabe via eli)

    HDFS-3583. Convert remaining tests to Junit4. (Andrew Wang via atm)

    HDFS-3711. Manually convert remaining tests to JUnit4. (Andrew Wang via atm)

    HDFS-3650. Use MutableQuantiles to provide latency histograms for various
    operations. (Andrew Wang via atm)

    HDFS-3667.  Add retry support to WebHdfsFileSystem.  (szetszwo)

    HDFS-3291. add test that covers HttpFS working w/ a non-HDFS Hadoop
    filesystem (tucu)

    HDFS-3634. Add self-contained, mavenized fuse_dfs test. (Colin Patrick
    McCabe via atm)

    HDFS-3190. Simple refactors in existing NN code to assist
    QuorumJournalManager extension. (todd)

    HDFS-3276. initializeSharedEdits should have a -nonInteractive flag (todd)

    HDFS-3765. namenode -initializeSharedEdits should be able to initialize
    all shared storages. (Vinay and todd via todd)

    HDFS-3723. Add support -h, -help to all the commands. (Jing Zhao via
    suresh)

    HDFS-3803. Change BlockPoolSliceScanner chatty INFO log to DEBUG.
    (Andrew Purtell via suresh)

    HDFS-3802. StartupOption.name in HdfsServerConstants should be final.
    (Jing Zhao via szetszwo)

    HDFS-3796. Speed up edit log tests by avoiding fsync() (todd)

    HDFS-2963. Console Output is confusing while executing metasave
    (dfsadmin command). (Andrew Wang via eli)

    HDFS-3672. Expose disk-location information for blocks to enable better
    scheduling. (Andrew Wang via atm)

    HDFS-2727. libhdfs should get the default block size from the server.
    (Colin Patrick McCabe via eli)

    HDFS-3832. Remove protocol methods related to DistributedUpgrade. (suresh)

    HDFS-3819. Should check whether invalidate work percentage default value is
    not greater than 1.0f. (Jing Zhao via jitendra)

    HDFS-3177. Update DFSClient and DataXceiver to handle different checkum
    types in file checksum computation.  (Kihwal Lee via szetszwo)

    HDFS-3844. Add @Override and remove {@inheritdoc} and unnecessary
    imports. (Jing Zhao via suresh)

    HDFS-3853. Port MiniDFSCluster enableManagedDfsDirsRedundancy
    option to branch-2. (Colin Patrick McCabe via eli)

    HDFS-3871. Change NameNodeProxies to use RetryUtils.  (Arun C Murthy
    via szetszwo)

    HDFS-3887. Remove redundant chooseTarget methods in BlockPlacementPolicy.
    (Jing Zhao via szetszwo)

    HDFS-3888. Clean up BlockPlacementPolicyDefault.  (Jing Zhao via szetszwo)

    HDFS-3907. Allow multiple users for local block readers. (eli)

    HDFS-3510. Editlog pre-allocation is performed prior to writing edits
    to avoid partial edits case disk out of space. (Colin McCabe via todd)

    HDFS-3910. DFSTestUtil#waitReplication should timeout. (eli)
    
    HDFS-3920. libwebdhfs string processing and using strerror consistently
    to handle all errors. (Jing Zhao via suresh)

  OPTIMIZATIONS

    HDFS-2982. Startup performance suffers when there are many edit log
    segments. (Colin Patrick McCabe via todd)

    HDFS-2834. Add a ByteBuffer-based read API to DFSInputStream.
    (Henry Robinson via todd)

    HDFS-3110. Use directRead API to reduce the number of buffer copies in
    libhdfs (Henry Robinson via todd)

    HDFS-3697. Enable fadvise readahead by default. (todd)

    HDFS-2421. Improve the concurrency of SerialNumberMap in NameNode.
    (Jing Zhao and Weiyan Wang via szetszwo)

    HDFS-3866. HttpFS POM should have property where to download tomcat from (zero45 via tucu)

  BUG FIXES

    HDFS-3385. The last block of INodeFileUnderConstruction is not
    necessarily a BlockInfoUnderConstruction, so do not cast it in
    FSNamesystem.recoverLeaseInternal(..).  (szetszwo)

    HDFS-3414. Balancer does not find NameNode if rpc-address or
    servicerpc-address are not set in client configs. (atm)

    HDFS-3031. Fix complete() and getAdditionalBlock() RPCs to be idempotent
    (todd)

    HDFS-2759. Pre-allocate HDFS edit log files after writing version number.
    (atm)

    HDFS-3413. TestFailureToReadEdits timing out. (atm)

    HDFS-3422. TestStandbyIsHot timeouts too aggressive (todd)

    HDFS-3433. GetImageServlet should allow administrative requestors when
    security is enabled. (atm)

    HDFS-1153. dfsnodelist.jsp should handle invalid input parameters.
    (Ravi Phulari via eli)

    HDFS-3434. InvalidProtocolBufferException when visiting DN
    browseDirectory.jsp (eli)

    HDFS-2800. Fix cancellation of checkpoints in the standby node to be more
    reliable. (todd)

    HDFS-3391. Fix InvalidateBlocks to compare blocks including their
    generation stamps. (todd)

    HDFS-3444. hdfs groups command doesn't work with security enabled. (atm)

    HDFS-2717. BookKeeper Journal output stream doesn't check addComplete rc.
    (Ivan Kelly via umamahesh)

    HDFS-3415. Make sure all layout versions are the same for all storage
    directories in the Namenode.  (Brandon Li via szetszwo)

    HDFS-3436. In DataNode.transferReplicaForPipelineRecovery(..), it should
    use the stored generation stamp to check if the block is valid.  (Vinay
    via szetszwo)

    HDFS-3460. HttpFS proxyuser validation with Kerberos ON uses full 
    principal name. (tucu)

    HDFS-3058. HA: Bring BookKeeperJournalManager up to date with HA changes.
    (Ivan Kelly via umamahesh)

    HDFS-3368. Missing blocks due to bad DataNodes coming up and down. (shv)

    HDFS-3452. BKJM:Switch from standby to active fails and NN gets shut down
    due to delay in clearing of lock. (umamahesh)

    HDFS-3398. Client will not retry when primaryDN is down once it's just got pipeline.
    (Amith D K via umamahesh)

    HDFS-3474. Cleanup Exception handling in BookKeeper journal manager.
    (Ivan Kelly via umamahesh)

    HDFS-3468. Make BKJM-ZK session timeout configurable. (umamahesh)

    HDFS-3423. BKJM: NN startup is failing, when tries to recoverUnfinalizedSegments()
    a bad inProgress_ ZNodes. (Ivan Kelly and Uma via umamahesh)

    HDFS-3441. Race condition between rolling logs at active NN and purging at standby.
    (Rakesh R via umamahesh)

    HDFS-3484. hdfs fsck doesn't work if NN HTTP address is set to
    0.0.0.0 even if NN RPC address is configured. (atm via eli)

    HDFS-3486. offlineimageviewer can't read fsimage files that contain
    persistent delegation tokens. (Colin Patrick McCabe via eli)

    HDFS-3487. offlineimageviewer should give byte offset information
    when it encounters an exception. (Colin Patrick McCabe via eli)

    HDFS-3442. Incorrect count for Missing Replicas in FSCK report. (Andrew
    Wang via atm)

    HDFS-2025. Go Back to File View link is not working in tail.jsp.
    (Ashish and Sravan via umamahesh)

    HDFS-3501. Checkpointing with security enabled will stop working
    after ticket lifetime expires. (atm via eli)

    HDFS-3266. DFSTestUtil#waitCorruptReplicas doesn't sleep between checks.
    (Madhukara Phatak via atm)

    HDFS-3505. DirectoryScanner does not join all threads in shutdown.
    (Colin Patrick McCabe via eli)

    HDFS-3485. DataTransferThrottler will over-throttle when currentTimeMillis
    jumps (Andy Isaacson via todd)

    HDFS-2914. HA: Standby should not enter safemode when resources are low.
    (Vinay via atm)

    HDFS-3235. MiniDFSClusterManager doesn't correctly support -format option.
    (Henry Robinson via atm)

    HDFS-3514. Add missing TestParallelLocalRead. (Henry Robinson via atm)

    HDFS-3243. TestParallelRead timing out on jenkins. (Henry Robinson via todd)

    HDFS-3490. DatanodeWebHdfsMethods throws NullPointerException if
    NamenodeRpcAddressParam is not set.  (szetszwo)

    HDFS-2797. Fix misuses of InputStream#skip in the edit log code.
    (Colin Patrick McCabe via eli)

    HDFS-3517. TestStartup should bind ephemeral ports. (eli)

    HDFS-3522. If a namenode is in safemode, it should throw SafeModeException
    when getBlockLocations has zero locations.  (Brandon Li via szetszwo)

    HDFS-3408. BKJM : Namenode format fails, if there is no BK root. (Rakesh R via umamahesh)

    HDFS-3389. Document the BKJM usage in Namenode HA. (umamahesh and Ivan Kelly via umamahesh)

    HDFS-3531. EditLogFileOutputStream#preallocate should check for
    incomplete writes. (Colin Patrick McCabe via eli)

    HDFS-766. Error message not clear for set space quota out of boundary
    values. (Jon Zuanich via atm)

    HDFS-3480. Multiple SLF4J binding warning. (Vinay via eli)

    HDFS-3524. Update TestFileLengthOnClusterRestart for HDFS-3522.  (Brandon
    Li via szetszwo)

    HDFS-3559. DFSTestUtil: use Builder class to construct DFSTestUtil
    instances. (Colin Patrick McCabe via atm)

    HDFS-3551. WebHDFS CREATE should use client location for HTTP redirection.
    (szetszwo)

    HDFS-3157. Fix a bug in the case that the generation stamps of the stored
    block in a namenode and the reported block from a datanode do not match.
    (Ashish Singhi via szetszwo)

    HDFS-3575. HttpFS does not log Exception Stacktraces (brocknoland via tucu)

    HDFS-3574. Fix small race and do some cleanup in GetImageServlet (todd)

    HDFS-3581. FSPermissionChecker#checkPermission sticky bit check
    missing range check. (eli)

    HDFS-3541. Deadlock between recovery, xceiver and packet responder.
    (Vinay via umamahesh)

    HDFS-3428. Move DelegationTokenRenewer to common (tucu)

    HDFS-3491. HttpFs does not set permissions correctly (tucu)

    HDFS-3580. incompatible types; no instance(s) of type variable(s) V exist 
    so that V conforms to boolean compiling HttpFSServer.java with OpenJDK 
    (adi2 via tucu)

    HDFS-3603. Decouple TestHDFSTrash from TestTrash. (Jason Lowe via eli)

    HDFS-711. hdfsUtime does not handle atime = 0 or mtime = 0 correctly.
    (Colin Patrick McCabe via eli)

    HDFS-3548. NamenodeFsck.copyBlock fails to create a Block Reader.
    (Colin Patrick McCabe via eli)

    HDFS-3615. Two BlockTokenSecretManager findbugs warnings. (atm)

    HDFS-470. libhdfs should handle 0-length reads from FSInputStream
    correctly. (Colin Patrick McCabe via eli)

    HDFS-3492. fix some misuses of InputStream#skip.
    (Colin Patrick McCabe via eli)

    HDFS-3609. libhdfs: don't force the URI to look like hdfs://hostname:port.
    (Colin Patrick McCabe via eli)

    HDFS-2966 TestNameNodeMetrics tests can fail under load. (stevel)

    HDFS-3605. Block mistakenly marked corrupt during edit log catchup
    phase of failover. (todd and Brahma Reddy Battula via todd)

    HDFS-3690. BlockPlacementPolicyDefault incorrectly casts LOG. (eli)

    HDFS-3597. SNN fails to start after DFS upgrade. (Andy Isaacson via todd)

    HDFS-3608. fuse_dfs: detect changes in UID ticket cache. (Colin Patrick
    McCabe via atm)

    HDFS-3709. TestStartup tests still binding to the ephemeral port. (eli)

    HDFS-3720. hdfs.h must get packaged. (Colin Patrick McCabe via atm)

    HDFS-3626. Creating file with invalid path can corrupt edit log (todd)

    HDFS-3679. fuse_dfs notrash option sets usetrash. (Conrad Meyer via suresh)

    HDFS-3732. fuse_dfs: incorrect configuration value checked for connection
    expiry timer period. (Colin Patrick McCabe via atm)

    HDFS-3738. TestDFSClientRetries#testFailuresArePerOperation sets incorrect
    timeout config. (atm)

    HDFS-3756. DelegationTokenFetcher creates 2 HTTP connections, the second 
    one not properly configured. (tucu)

    HDFS-3579. libhdfs: fix exception handling. (Colin Patrick McCabe via atm)

    HDFS-3754. BlockSender doesn't shutdown ReadaheadPool threads. (eli)

    HDFS-3760. primitiveCreate is a write, not a read. (Andy Isaacson via atm)

    HDFS-3710. libhdfs misuses O_RDONLY/WRONLY/RDWR. (Andy Isaacson via atm)

    HDFS-3721. hsync support broke wire compatibility. (todd and atm)

    HDFS-3758. TestFuseDFS test failing. (Colin Patrick McCabe via eli)

    HDFS-2330. In NNStorage.java, IOExceptions of stream closures can mask
    root exceptions. (umamahesh via todd)

    HDFS-3790. test_fuse_dfs.c doesn't compile on centos 5. (Colin Patrick
    McCabe via atm)

    HDFS-3658. Fix bugs in TestDFSClientRetries and add more tests.  (szetszwo)

    HDFS-3794. WebHDFS OPEN returns the incorrect Content-Length in the HTTP
    header when offset is specified and length is omitted.
    (Ravi Prakash via szetszwo)

    HDFS-3048. Small race in BlockManager#close. (Andy Isaacson via eli)

    HDFS-3194. DataNode block scanner is running too frequently.
    (Andy Isaacson via eli)

    HDFS-3808. fuse_dfs: postpone libhdfs intialization until after fork.
    (Colin Patrick McCabe via atm)

    HDFS-3788. ByteRangeInputStream should not expect HTTP Content-Length header
    when chunked transfer-encoding is used.  (szetszwo)

    HDFS-3816. Invalidate work percentage default value should be 0.32f
    instead of 32. (Jing Zhao via suresh)

    HDFS-3707. TestFSInputChecker: improper use of skip.
    (Colin Patrick McCabe via eli)

    HDFS-3830. test_libhdfs_threaded: use forceNewInstance.
    (Colin Patrick McCabe via eli)

    HDFS-3835. Long-lived 2NN cannot perform a checkpoint if security is
    enabled and the NN restarts with outstanding delegation tokens. (atm)

    HDFS-3715. Fix TestFileCreation#testFileCreationNamenodeRestart.
    (Andrew Whang via eli)

    HDFS-3683. Edit log replay progress indicator shows >100% complete. (Plamen
    Jeliazkov via atm)

    HDFS-3731. Release upgrade must handle blocks being written from 1.0.
    (Colin Patrick McCabe via eli)

    HDFS-3856. TestHDFSServerPorts failure is causing surefire fork failure.
    (eli)

    HDFS-3860. HeartbeatManager#Monitor may wrongly hold the writelock of
    namesystem. (Jing Zhao via atm)

    HDFS-3849. When re-loading the FSImage, we should clear the existing
    genStamp and leases. (Colin Patrick McCabe via atm)

    HDFS-3864. NN does not update internal file mtime for OP_CLOSE when reading
    from the edit log. (atm)

    HDFS-3837. Fix DataNode.recoverBlock findbugs warning. (eli)

    HDFS-3733. Audit logs should include WebHDFS access. (Andy Isaacson via 
    eli)

    HDFS-2686. Remove DistributedUpgrade related code. (suresh)

    HDFS-3833. TestDFSShell fails on windows due to concurrent file 
    read/write. (Brandon Li via suresh)

    HDFS-3466. Get HTTP kerberos principal from the web authentication keytab.
    (omalley)

    HDFS-3879. Fix findbugs warning in TransferFsImage on branch-2. (eli)

    HDFS-3469. start-dfs.sh will start zkfc, but stop-dfs.sh will not stop zkfc similarly.
    (Vinay via umamahesh)

    HDFS-1490. TransferFSImage should timeout (Dmytro Molkov and Vinay via todd)

    HDFS-3828. Block Scanner rescans blocks too frequently.
    (Andy Isaacson via eli)

    HDFS-3895. hadoop-client must include commons-cli (tucu)

    HDFS-2757. Cannot read a local block that's being written to when
    using the local read short circuit. (Jean-Daniel Cryans via eli)

    HDFS-3664. BlockManager race when stopping active services.
    (Colin Patrick McCabe via eli)

    HDFS-3928. MiniDFSCluster should reset the first ExitException on shutdown. (eli)
   
    HDFS-3938. remove current limitations from HttpFS docs. (tucu)

    HDFS-3944. Httpfs resolveAuthority() is not resolving host correctly. (tucu)

    HDFS-3972. Trash emptier fails in secure HA cluster. (todd via eli)

    HDFS-4443. Remove a trailing '`' character from the HTML code generated by
    NamenodeJspHelper.generateNodeData(..).  (Christian Rohling via szetszwo)
 
  BREAKDOWN OF HDFS-3042 SUBTASKS

    HDFS-2185. HDFS portion of ZK-based FailoverController (todd)
    
    HDFS-3200. Scope all ZKFC configurations by nameservice (todd)
    
    HDFS-3223. add zkfc to hadoop-daemon.sh script (todd)
    
    HDFS-3261. TestHASafeMode fails on HDFS-3042 branch (todd)
    
    HDFS-3159. Document NN auto-failover setup and configuration (todd)
    
    HDFS-3412. Fix findbugs warnings in auto-HA branch (todd)
    
    HDFS-3432. TestDFSZKFailoverController tries to fail over too early (todd)

    HDFS-3902. TestDatanodeBlockScanner#testBlockCorruptionPolicy is broken.
    (Andy Isaacson via eli)

Release 2.0.0-alpha - 05-23-2012

  INCOMPATIBLE CHANGES

    HDFS-2676. Remove Avro RPC. (suresh)

    HDFS-2303. Unbundle jsvc. (Roman Shaposhnik and Mingjie Lai via eli)

    HDFS-3137. Bump LAST_UPGRADABLE_LAYOUT_VERSION to -16. (eli)
    
    HDFS-3138. Move DatanodeInfo#ipcPort to DatanodeID. (eli)

    HDFS-3164. Move DatanodeInfo#hostName to DatanodeID. (eli)

  NEW FEATURES

    HDFS-2978. The NameNode should expose name dir statuses via JMX. (atm)

    HDFS-395.  DFS Scalability: Incremental block reports. (Tomasz Nykiel
    via hairong)

    HDFS-2517. Add protobuf service for JounralProtocol. (suresh)

    HDFS-2518. Add protobuf service for NamenodeProtocol. (suresh)

    HDFS-2520. Add protobuf service for InterDatanodeProtocol. (suresh)

    HDFS-2519. Add protobuf service for DatanodeProtocol. (suresh)

    HDFS-2581. Implement protobuf service for JournalProtocol. (suresh)

    HDFS-2618. Implement protobuf service for NamenodeProtocol. (suresh)

    HDFS-2629. Implement protobuf service for InterDatanodeProtocol. (suresh)

    HDFS-2636. Implement protobuf service for ClientDatanodeProtocol. (suresh)

    HDFS-2642. Protobuf translators for DatanodeProtocol. (jitendra)

    HDFS-2647. Used protobuf based RPC for InterDatanodeProtocol, 
    ClientDatanodeProtocol, JournalProtocol, NamenodeProtocol. (suresh)

    HDFS-2661. Enable protobuf RPC for DatanodeProtocol. (jitendra)

    HDFS-2697. Move RefreshAuthPolicy, RefreshUserMappings, GetUserMappings 
    protocol to protocol buffers. (jitendra)

    HDFS-2880. Protobuf changes in DatanodeProtocol to add multiple storages.
    (suresh)

    HDFS-2899. Service protocol changes in DatanodeProtocol to add multiple 
    storages. (suresh)

    HDFS-2430. The number of failed or low-resource volumes the NN can tolerate
    should be configurable. (atm)

    HDFS-1623. High Availability Framework for HDFS NN. Contributed by Todd
    Lipcon, Aaron T. Myers, Eli Collins, Uma Maheswara Rao G, Bikas Saha,
    Suresh Srinivas, Jitendra Nath Pandey, Hari Mankude, Brandon Li, Sanjay
    Radia, Mingjie Lai, and Gregory Chanan

    HDFS-2941. Add an administrative command to download a copy of the fsimage
    from the NN. (atm)

    HDFS-2413. Add an API DistributedFileSystem.isInSafeMode() and change
    DistributedFileSystem to @InterfaceAudience.LimitedPrivate.
    (harsh via szetszwo)

    HDFS-3167. CLI-based driver for MiniDFSCluster. (Henry Robinson via atm)

    HDFS-3148. The client should be able to use multiple local interfaces
    for data transfer. (eli)

    HDFS-3000. Add a public API for setting quotas. (atm)

    HDFS-3102. Add CLI tool to initialize the shared-edits dir. (atm)

    HDFS-3004. Implement Recovery Mode. (Colin Patrick McCabe via eli)

    HDFS-3282. Add HdfsDataInputStream as a public API. (umamahesh)

    HDFS-3298. Add HdfsDataOutputStream as a public API.  (szetszwo)

    HDFS-234. Integration with BookKeeper logging system. (Ivan Kelly 
    via umamahesh)

  IMPROVEMENTS

    HDFS-2018. Move all journal stream management code into one place.
    (Ivan Kelly via jitendra)

    HDFS-2223. Untangle depencencies between NN components (todd)

    HDFS-2351. Change Namenode and Datanode to register each of their protocols
    seperately (sanjay)

    HDFS-2337. DFSClient shouldn't keep multiple RPC proxy references (atm)
 
    HDFS-2181. Separate HDFS Client wire protocol data types (sanjay)

    HDFS-2459. Separate datatypes for Journal Protocol. (suresh)

    HDFS-2480. Separate datatypes for NamenodeProtocol. (suresh)

    HDFS-2489. Move Finalize and Register to separate file out of
    DatanodeCommand.java. (suresh)

    HDFS-2488. Separate datatypes for InterDatanodeProtocol. (suresh)

    HDFS-2496. Separate datatypes for DatanodeProtocol. (suresh)

    HDFS-2479. HDFS Client Data Types in Protocol Buffers (sanjay)

    HADOOP-7862. Hdfs changes to work with HADOOP-7862: Move the support for
    multiple protocols to lower layer so that Writable, PB and Avro can all
    use it. (sanjay)

    HDFS-2597. ClientNameNodeProtocol in Protocol Buffers. (sanjay)

    HDFS-2651. ClientNameNodeProtocol Translators for Protocol Buffers. (sanjay)

    HDFS-2650. Replace @inheritDoc with @Override. (Hari Mankude via suresh).

    HDFS-2669. Enable protobuf rpc for ClientNamenodeProtocol. (sanjay)

    HDFS-2801. Provide a method in client side translators to check for a 
    methods supported in underlying protocol. (jitendra)

    HDFS-2895. Remove Writable wire protocol types and translators to
    complete transition to protocol buffers. (suresh)

    HDFS-2992. Edit log failure trace should include transaction ID of
    error.  (Colin Patrick McCabe via eli)

    HDFS-3030. Remove getProtocolVersion and getProtocolSignature from 
    translators. (jitendra)

    HDFS-2158. Add JournalSet to manage the set of journals. (jitendra)

    HDFS-2334. Add Closeable to JournalManager. (Ivan Kelly via jitendra)

    HDFS-1580. Add interface for generic Write Ahead Logging mechanisms.
    (Ivan Kelly via jitendra)

    HDFS-3060. Bump TestDistributedUpgrade#testDistributedUpgrade timeout (eli)

    HDFS-2410. Further cleanup of hardcoded configuration keys and values.
    (suresh)

    HDFS-2878. Fix TestBlockRecovery and move it back into main test directory.
    (todd)

    HDFS-3003. Remove getHostPortString() from NameNode, replace it with
    NetUtils.getHostPortString(). (Brandon Li via atm)

    HDFS-3014. FSEditLogOp and its subclasses should have toString() method.
    (Sho Shimauchi via atm)

    HDFS-3021. Use generic type to declare FSDatasetInterface.  (szetszwo)

    HDFS-3056.  Add a new interface RollingLogs for DataBlockScanner logging.
    (szetszwo)

    HDFS-2731. Add command to bootstrap the Standby Node's name directories
    from the Active NameNode. (todd)

    HDFS-3082. Clean up FSDatasetInterface and change DataNode.data to package
    private.  (szetszwo)

    HDFS-3057. httpfs and hdfs launcher scripts should honor CATALINA_HOME 
    and HADOOP_LIBEXEC_DIR (rvs via tucu)

    HDFS-3088. Move FSDatasetInterface inner classes to a package.  (szetszwo)

    HDFS-3111. Missing license headers in trunk. (umamahesh)

    HDFS-3091. Update the usage limitations of ReplaceDatanodeOnFailure policy in
    the config description for the smaller clusters. (szetszwo via umamahesh)

    HDFS-3105. Add DatanodeStorage information to block recovery.  (szetszwo)

    HDFS-3086. Change Datanode not to send storage list in registration.
    (szetszwo)

    HDFS-309. FSEditLog should log progress during replay. (Sho Shimauchi
    via todd)

    HDFS-3044. fsck move should be non-destructive by default.
    (Colin Patrick McCabe via eli)

    HDFS-3071. haadmin failover command does not provide enough detail when
    target NN is not ready to be active. (todd)

    HDFS-3089. Move FSDatasetInterface and the related classes to a package.
    (szetszwo)

    HDFS-3129. NetworkTopology: add test that getLeaf should check for
    invalid topologies. (Colin Patrick McCabe via eli)

    HDFS-3155. Clean up FSDataset implemenation related code.  (szetszwo)

    HDFS-3158. LiveNodes member of NameNodeMXBean should list non-DFS used
    space and capacity per DN. (atm)

    HDFS-3172. dfs.upgrade.permission is dead code. (eli)

    HDFS-3171. The DatanodeID "name" field is overloaded. (eli)

    HDFS-3144. Refactor DatanodeID#getName by use. (eli)

    HDFS-3130. Move fsdataset implementation to a package.  (szetszwo)

    HDFS-3120. Enable hsync and hflush by default. (eli)

    HDFS-3187. Upgrade guava to 11.0.2 (todd)

    HDFS-3168. Remove unnecessary "throw IOException" and change fields to
    final in FSNamesystem and BlockManager.  (szetszwo)

    HDFS-2564. Cleanup unnecessary exceptions thrown and unnecessary casts.
    (Hari Mankude via eli)

    HDFS-3084. FenceMethod.tryFence() and ShellCommandFencer should pass
    namenodeId as well as host:port (todd)

    HDFS-3050. rework OEV to share more code with the NameNode.
    (Colin Patrick McCabe via eli)

    HDFS-3204. Minor modification to JournalProtocol.proto to make
    it generic. (suresh)

    HDFS-3226. Allow GetConf tool to print arbitrary keys (todd)

    HDFS-3240. Drop log level of "heartbeat: ..." in BPServiceActor to DEBUG
    (todd)

    HDFS-3238. ServerCommand and friends don't need to be writables. (eli)

    HDFS-3094. add -nonInteractive and -force option to namenode -format
    command (Arpit Gupta via todd)

    HDFS-3244. Remove dead writable code from hdfs/protocol. (eli)

    HDFS-3247. Improve bootstrapStandby behavior when original NN is not active
    (todd)

    HDFS-3249. Use ToolRunner.confirmPrompt in NameNode (todd)

    HDFS-3179.  Improve the exception message thrown by DataStreamer when 
    it failed to add a datanode.  (szetszwo)

    HDFS-2983. Relax the build version check to permit rolling upgrades within a release. (atm)

    HDFS-3259. NameNode#initializeSharedEdits should populate shared edits dir
    with edit log segments. (atm)

    HDFS-2708. Stats for the # of blocks per DN. (atm)

    HDFS-3279. Move the FSEditLog constructor with @VisibleForTesting to
    TestEditLog.  (Arpit Gupta via szetszwo)

    HDFS-3294. Fix code indentation in NamenodeWebHdfsMethods and
    DatanodeWebHdfsMethods.  (szetszwo)

    HDFS-3263. HttpFS should read HDFS config from Hadoop site.xml files (tucu)

    HDFS-3206. Miscellaneous xml cleanups for OEV.
    (Colin Patrick McCabe via eli)

    HDFS-3169. TestFsck should test multiple -move operations in a row.
    (Colin Patrick McCabe via eli)

    HDFS-3258. Test for HADOOP-8144 (pseudoSortByDistance in
    NetworkTopology for first rack local node). (Junping Du via eli)

    HDFS-3322. Use HdfsDataInputStream and HdfsDataOutputStream in Hdfs.
    (szetszwo)

    HDFS-3339. Change INode to package private.  (John George via szetszwo)

    HDFS-3303. Remove Writable implementation from RemoteEditLogManifest.
    (Brandon Li via szetszwo)

    HDFS-2617. Replaced Kerberized SSL for image transfer and fsck
    with SPNEGO-based solution. (jghoman, omalley, tucu, and atm via eli)

    HDFS-3365. Enable users to disable socket caching in DFS client
    configuration (todd)

    HDFS-3375. Put client name in DataXceiver thread name for readBlock
    and keepalive (todd)

    HDFS-3363. Define BlockCollection and MutableBlockCollection interfaces
    so that INodeFile and INodeFileUnderConstruction do not have to be used in
    block management.  (John George via szetszwo)

    HDFS-3211. Add fence(..) and replace NamenodeRegistration with JournalInfo
    and epoch in JournalProtocol. (suresh via szetszwo)

    HADOOP-8285 HDFS changes for Use ProtoBuf for RpcPayLoadHeader (sanjay radia)

    HDFS-3418. Rename BlockWithLocationsProto datanodeIDs field to storageIDs.
    (eli)

  OPTIMIZATIONS

    HDFS-2477. Optimize computing the diff between a block report and the
    namenode state. (Tomasz Nykiel via hairong)

    HDFS-2495. Increase granularity of write operations in ReplicationMonitor
    thus reducing contention for write lock. (Tomasz Nykiel via hairong)

    HDFS-2476. More CPU efficient data structure for under-replicated,
    over-replicated, and invalidated blocks. (Tomasz Nykiel via todd)

    HDFS-3036. Remove unused method DFSUtil#isDefaultNamenodeAddress. (atm)

    HDFS-3378. Remove DFS_NAMENODE_SECONDARY_HTTPS_PORT_KEY and DEFAULT. (eli)

  BUG FIXES
 
    HDFS-2481. Unknown protocol: org.apache.hadoop.hdfs.protocol.ClientProtocol.
    (sanjay)

    HDFS-2497. Fix TestBackupNode failure. (suresh)

    HDFS-2499. RPC client is created incorrectly introduced in HDFS-2459.
    (suresh)

    HDFS-2526. (Client)NamenodeProtocolTranslatorR23 do not need to keep a
    reference to rpcProxyWithoutRetry (atm)

    HDFS-2532. TestDfsOverAvroRpc timing out in trunk (Uma Maheswara Rao G
    via todd)

    HDFS-2666. Fix TestBackupNode failure. (suresh)

    HDFS-2663. Optional protobuf parameters are not handled correctly. (suresh)

    HDFS-2694. Removal of Avro broke non-PB NN services. (atm)

    HDFS-2687. Tests failing with ClassCastException post protobuf RPC
    changes. (suresh)

    HDFS-2700. Fix failing TestDataNodeMultipleRegistrations in trunk
    (Uma Maheswara Rao G via todd)

    HDFS-2739. SecondaryNameNode doesn't start up. (jitendra)

    HDFS-2768. BackupNode stop can not close proxy connections because
    it is not a proxy instance. (Uma Maheswara Rao G via eli)

    HDFS-2968. Protocol translator for BlockRecoveryCommand broken when
    multiple blocks need recovery. (todd)

    HDFS-3020. Fix editlog to automatically sync when buffer is full. (todd)

    HDFS-3038. Add FSEditLog.metrics to findbugs exclude list. (todd via atm)

    HDFS-2188. Make FSEditLog create its journals from a list of URIs rather 
    than NNStorage. (Ivan Kelly via jitendra)

    HDFS-1765. Block Replication should respect under-replication
    block priority. (Uma Maheswara Rao G via eli)

    HDFS-2285. BackupNode should reject requests to modify namespace.
    (shv and Uma Maheswara Rao)

    HDFS-2764. TestBackupNode is racy. (atm)

    HDFS-3093. Fix bug where namenode -format interpreted the -force flag in
    reverse. (todd)

    HDFS-3005. FSVolume.decDfsUsed(..) should be synchronized.  (szetszwo)

    HDFS-3099. SecondaryNameNode does not properly initialize metrics system.
    (atm)

    HDFS-3062. Fix bug which prevented MR job submission from creating
    delegation tokens on an HA cluster. (Mingjie Lai via todd)

    HDFS-3083. Cannot run an MR job with HA and security enabled when
    second-listed NN active. (atm)

    HDFS-3100. In BlockSender, throw an exception when it needs to verify
    checksum but the meta data does not exist.  (Brandon Li via szetszwo)

    HDFS-3132. Fix findbugs warning on HDFS trunk. (todd)

    HDFS-3156. TestDFSHAAdmin is failing post HADOOP-8202. (atm)

    HDFS-3143. TestGetBlocks.testGetBlocks is failing. (Arpit Gupta via atm)

    HDFS-3142. TestHDFSCLI.testAll is failing. (Brandon Li via atm)

    HDFS-3070. HDFS balancer doesn't ensure that hdfs-site.xml is loaded. (atm)

    HDFS-2995. start-dfs.sh should only start the 2NN for namenodes
    with dfs.namenode.secondary.http-address configured. (eli)

    HDFS-3174. Fix assert in TestPendingDataNodeMessages. (eli)

    HDFS-3199. TestValidateConfigurationSettings is failing. (todd via eli)

    HDFS-3202. NamespaceInfo PB translation drops build version. (atm)

    HDFS-3109. Remove hsqldf exclusions from pom.xml. (Ravi Prakash
    via suresh)

    HDFS-3210. JsonUtil#toJsonMap for for a DatanodeInfo should use
    "ipAddr" instead of "name". (eli)

    HDFS-3208. Bogus entries in hosts files are incorrectly displayed
    in the report. (eli)

    HDFS-3136. Remove SLF4J dependency as HDFS does not need it to fix
    unnecessary warnings. (Jason Lowe via suresh)

    HDFS-3214. InterDatanodeProtocolServerSideTranslatorPB doesn't handle
    null response from initReplicaRecovery (todd)

    HDFS-3119. Overreplicated block is not deleted even after the replication 
    factor is reduced after sync follwed by closing that file. (Ashish Singhi 
    via umamahesh)

    HDFS-3234. Accidentally left log message in GetConf after HDFS-3226 (todd)

    HDFS-3236. NameNode does not initialize generic conf keys when started
    with -initializeSharedEditsDir (atm)

    HDFS-3248. bootstrapStandby repeated twice in hdfs namenode usage message
    (Colin Patrick McCabe via todd)

    HDFS-2696. Fix the fuse-fds build. (Bruno Mahé via eli)

    HDFS-3254. Branch-2 build broken due to wrong version number in
    fuse-dfs' pom.xml. (Anupam Seth via eli)

    HDFS-3260. TestDatanodeRegistration should set minimum DN version in
    addition to minimum NN version. (atm)

    HDFS-3255. HA DFS returns wrong token service (Daryn Sharp via todd)

    HDFS-3256. HDFS considers blocks under-replicated if topology script is
    configured with only 1 rack. (atm)

    HDFS-2799. Trim fs.checkpoint.dir values. (Amith D K via eli)

    HDFS-2765. TestNameEditsConfigs is incorrectly swallowing IOE. (atm)

    HDFS-3280. DFSOutputStream.sync should not be synchronized (todd)

    HDFS-3268. FileContext API mishandles token service and incompatible with
    HA (Daryn Sharp via todd)

    HDFS-3284. bootstrapStandby fails in secure cluster (todd)

    HDFS-3165. HDFS Balancer scripts are refering to wrong path of
    hadoop-daemon.sh (Amith D K via eli)

    HDFS-891. DataNode no longer needs to check for dfs.network.script.
    (harsh via eli)

    HDFS-3305. GetImageServlet should consider SBN a valid requestor in a
    secure HA setup. (atm)

    HDFS-3314. HttpFS operation for getHomeDirectory is incorrect. (tucu)

    HDFS-3319. Change DFSOutputStream to not to start a thread in constructors.
    (szetszwo)

    HDFS-3222. DFSInputStream#openInfo should not silently get the length as 0 
    when locations length is zero for last partial block. (umamahesh)

    HDFS-3181. Fix a test case in TestLeaseRecovery2.  (szetszwo)

    HDFS-3309. HttpFS (Hoop) chmod not supporting octal and sticky bit 
    permissions. (tucu)

    HDFS-3326. Append enabled log message uses the wrong variable.
    (Matthew Jacobs via eli)

    HDFS-3275. Skip format for non-file based directories. 
    (Amith D K via umamahesh)

    HDFS-3286. When the threshold value for balancer is zero, unexpected output is displayed.
    (Ashish Singhi via umamahesh)

    HDFS-3336. hdfs launcher script will be better off not special casing 
    namenode command with regards to hadoop.security.logger (rvs via tucu)

    HDFS-3330. If GetImageServlet throws an Error or RTE, response should not
    have HTTP "OK" status. (todd)

    HDFS-3351. NameNode#initializeGenericKeys should always set fs.defaultFS
    regardless of whether HA or Federation is enabled. (atm)

    HDFS-3332. NullPointerException in DN when directoryscanner is trying to 
    report bad blocks. (Amith D K via umamahesh)

    HDFS-3359. DFSClient.close should close cached sockets. (todd)

    HDFS-3350. In INode, add final to compareTo(..), equals(..) and hashCode(),
    and remove synchronized from updatePermissionStatus(..).  (szetszwo)

    HDFS-3357. DataXceiver reads from client socket with incorrect/no timeout
    (todd)

    HDFS-3376. DFSClient fails to make connection to DN if there are many
    unusable cached sockets (todd)

    HDFS-3328. NPE in DataNode.getIpcPort. (eli)

    HDFS-3396. FUSE build fails on Ubuntu 12.04. (Colin Patrick McCabe via eli)

    HDFS-3395. NN doesn't start with HA+security enabled and HTTP address set to 0.0.0.0. (atm)

    HDFS-3026. HA: Handle failure during HA state transition. (atm)

    HDFS-860. fuse-dfs truncate behavior causes issues with scp.
    (Brian Bockelman via eli)

  BREAKDOWN OF HDFS-1623 SUBTASKS

    HDFS-2179. Add fencing framework and mechanisms for NameNode HA. (todd)
    
    HDFS-1974. Introduce active and standy states to the namenode. (suresh)
    
    HDFS-2407. getServerDefaults and getStats don't check operation category (atm)
    
    HDFS-1973. HA: HDFS clients must handle namenode failover and switch over to
    the new active namenode. (atm)
    
    HDFS-2301. Start/stop appropriate namenode services when transition to active
    and standby states. (suresh)
    
    HDFS-2231. Configuration changes for HA namenode. (suresh)
    
    HDFS-2418. Change ConfiguredFailoverProxyProvider to take advantage of
    HDFS-2231. (atm)
    
    HDFS-2393. Mark appropriate methods of ClientProtocol with the idempotent
    annotation. (atm)
    
    HDFS-2523. Small NN fixes to include HAServiceProtocol and prevent NPE on
    shutdown. (todd)
    
    HDFS-2577. NN fails to start since it tries to start secret manager in
    safemode. (todd)
    
    HDFS-2582. Scope dfs.ha.namenodes config by nameservice (todd)
    
    HDFS-2591. MiniDFSCluster support to mix and match federation with HA (todd)
    
    HDFS-1975. Support for sharing the namenode state from active to standby.
    (jitendra, atm, todd)
    
    HDFS-1971. Send block report from datanode to both active and standby
    namenodes. (sanjay, todd via suresh)
    
    HDFS-2616. Change DatanodeProtocol#sendHeartbeat() to return HeartbeatResponse.
    (suresh)
    
    HDFS-2622. Fix TestDFSUpgrade in HA branch. (todd)
    
    HDFS-2612. Handle refreshNameNodes in federated HA clusters (todd)
    
    HDFS-2623. Add test case for hot standby capability (todd)
    
    HDFS-2626. BPOfferService.verifyAndSetNamespaceInfo needs to be synchronized
    (todd)
    
    HDFS-2624. ConfiguredFailoverProxyProvider doesn't correctly stop
    ProtocolTranslators (todd)
    
    HDFS-2625. TestDfsOverAvroRpc failing after introduction of HeartbeatResponse
    type (todd)
    
    HDFS-2627. Determine DN's view of which NN is active based on heartbeat
    responses (todd)
    
    HDFS-2634. Standby needs to ingest latest edit logs before transitioning to
    active (todd)
    
    HDFS-2671. NN should throw StandbyException in response to RPCs in STANDBY
    state (todd)
    
    HDFS-2680. DFSClient should construct failover proxy with exponential backoff
    (todd)
    
    HDFS-2683. Authority-based lookup of proxy provider fails if path becomes
    canonicalized (todd)
    
    HDFS-2689. HA: BookKeeperEditLogInputStream doesn't implement isInProgress()
    (atm)
    
    HDFS-2602. NN should log newly-allocated blocks without losing BlockInfo (atm)
    
    HDFS-2667. Fix transition from active to standby (todd)
    
    HDFS-2684. Fix up some failing unit tests on HA branch (todd)
    
    HDFS-2679. Add interface to query current state to HAServiceProtocol (eli via
    todd)
    
    HDFS-2677. Web UI should indicate the NN state. (eli via todd)
    
    HDFS-2678. When a FailoverProxyProvider is used, DFSClient should not retry
    connection ten times before failing over (atm via todd)
    
    HDFS-2682. When a FailoverProxyProvider is used, Client should not retry for 45
    times if it is timing out to connect to server. (Uma Maheswara Rao G via todd)
    
    HDFS-2693. Fix synchronization issues around state transition (todd)
    
    HDFS-1972. Fencing mechanism for block invalidations and replications (todd)
    
    HDFS-2714. Fix test cases which use standalone FSNamesystems (todd)
    
    HDFS-2692. Fix bugs related to failover from/into safe mode. (todd)
    
    HDFS-2716. Configuration needs to allow different dfs.http.addresses for each
    HA NN (todd)
    
    HDFS-2720. Fix MiniDFSCluster HA support to work properly on Windows. (Uma
    Maheswara Rao G via todd)
    
    HDFS-2291. Allow the StandbyNode to make checkpoints in an HA setup. (todd)
    
    HDFS-2709. Appropriately handle error conditions in EditLogTailer (atm via
    todd)
    
    HDFS-2730. Refactor shared HA-related test code into HATestUtil class (todd)
    
    HDFS-2762. Fix TestCheckpoint timing out on HA branch. (Uma Maheswara Rao G via
    todd)
    
    HDFS-2724. NN web UI can throw NPE after startup, before standby state is
    entered. (todd)
    
    HDFS-2753. Fix standby getting stuck in safemode when blocks are written while
    SBN is down. (Hari Mankude and todd via todd)
    
    HDFS-2773. Reading edit logs from an earlier version should not leave blocks in
    under-construction state. (todd)
    
    HDFS-2775. Fix TestStandbyCheckpoints.testBothNodesInStandbyState failing
    intermittently. (todd)
    
    HDFS-2766. Test for case where standby partially reads log and then performs
    checkpoint. (atm)
    
    HDFS-2738. FSEditLog.selectinputStreams is reading through in-progress streams
    even when non-in-progress are requested. (atm)
    
    HDFS-2789. TestHAAdmin.testFailover is failing (eli)
    
    HDFS-2747. Entering safe mode after starting SBN can NPE. (Uma Maheswara Rao G
    via todd)
    
    HDFS-2772. On transition to active, standby should not swallow ELIE. (atm)
    
    HDFS-2767. ConfiguredFailoverProxyProvider should support NameNodeProtocol.
    (Uma Maheswara Rao G via todd)
    
    HDFS-2795. Standby NN takes a long time to recover from a dead DN starting up.
    (todd)
    
    HDFS-2592. Balancer support for HA namenodes. (Uma Maheswara Rao G via todd)
    
    HDFS-2367. Enable the configuration of multiple HA cluster addresses. (atm)
    
    HDFS-2812. When becoming active, the NN should treat all leases as freshly
    renewed. (todd)
    
    HDFS-2737. Automatically trigger log rolls periodically on the active NN. (todd
    and atm)
    
    HDFS-2820. Add a simple sanity check for HA config (todd)
    
    HDFS-2688. Add tests for quota tracking in an HA cluster. (todd)
    
    HDFS-2804. Should not mark blocks under-replicated when exiting safemode (todd)
    
    HDFS-2807. Service level authorizartion for HAServiceProtocol. (jitendra)
    
    HDFS-2809. Add test to verify that delegation tokens are honored after
    failover. (jitendra and atm)
    
    HDFS-2838. NPE in FSNamesystem when in safe mode. (Gregory Chanan via eli)
    
    HDFS-2805. Add a test for a federated cluster with HA NNs. (Brandon Li via
    jitendra)
    
    HDFS-2841. HAAdmin does not work if security is enabled. (atm)
    
    HDFS-2691. Fixes for pipeline recovery in an HA cluster: report RBW replicas
    immediately upon pipeline creation. (todd)
    
    HDFS-2824. Fix failover when prior NN died just after creating an edit log
    segment. (atm via todd)
    
    HDFS-2853. HA: NN fails to start if the shared edits dir is marked required
    (atm via eli)
    
    HDFS-2845. SBN should not allow browsing of the file system via web UI. (Bikas
    Saha via atm)
    
    HDFS-2742. HA: observed dataloss in replication stress test. (todd via eli)
    
    HDFS-2870. Fix log level for block debug info in processMisReplicatedBlocks
    (todd)
    
    HDFS-2859. LOCAL_ADDRESS_MATCHER.match has NPE when called from
    DFSUtil.getSuffixIDs when the host is incorrect (Bikas Saha via todd)
    
    HDFS-2861. checkpointing should verify that the dfs.http.address has been
    configured to a non-loopback for peer NN (todd)
    
    HDFS-2860. TestDFSRollback#testRollback is failing. (atm)
    
    HDFS-2769. HA: When HA is enabled with a shared edits dir, that dir should be
    marked required. (atm via eli)
    
    HDFS-2863. Failures observed if dfs.edits.dir and shared.edits.dir have same
    directories. (Bikas Saha via atm)
    
    HDFS-2874. Edit log should log to shared dirs before local dirs. (todd)
    
    HDFS-2890. DFSUtil#getSuffixIDs should skip unset configurations. (atm)
    
    HDFS-2792. Make fsck work. (atm)
    
    HDFS-2808. HA: haadmin should use namenode ids. (eli)
    
    HDFS-2819. Document new HA-related configs in hdfs-default.xml. (eli)
    
    HDFS-2752. HA: exit if multiple shared dirs are configured. (eli)
    
    HDFS-2894. HA: automatically determine the nameservice Id if only one
    nameservice is configured. (eli)
    
    HDFS-2733. Document HA configuration and CLI. (atm)
    
    HDFS-2794. Active NN may purge edit log files before standby NN has a chance to
    read them (todd)
    
    HDFS-2901. Improvements for SBN web UI - not show under-replicated/missing
    blocks. (Brandon Li via jitendra)
    
    HDFS-2905. HA: Standby NN NPE when shared edits dir is deleted. (Bikas Saha via
    jitendra)
    
    HDFS-2579. Starting delegation token manager during safemode fails. (todd)
    
    HDFS-2510. Add HA-related metrics. (atm)
    
    HDFS-2924. Standby checkpointing fails to authenticate in secure cluster.
    (todd)
    
    HDFS-2915. HA: TestFailureOfSharedDir.testFailureOfSharedDir() has race
    condition. (Bikas Saha via jitendra)
    
    HDFS-2912. Namenode not shutting down when shared edits dir is inaccessible.
    (Bikas Saha via atm)
    
    HDFS-2917. HA: haadmin should not work if run by regular user (eli)
    
    HDFS-2939. TestHAStateTransitions fails on Windows. (Uma Maheswara Rao G via
    atm)
    
    HDFS-2947. On startup NN throws an NPE in the metrics system. (atm)
    
    HDFS-2942. TestActiveStandbyElectorRealZK fails if build dir does not exist.
    (atm)
    
    HDFS-2948. NN throws NPE during shutdown if it fails to startup (todd)
    
    HDFS-2909. HA: Inaccessible shared edits dir not getting removed from FSImage
    storage dirs upon error. (Bikas Saha via jitendra)
    
    HDFS-2934. Allow configs to be scoped to all NNs in the nameservice. (todd)
    
    HDFS-2935. Shared edits dir property should be suffixed with nameservice and
    namenodeID (todd)
    
    HDFS-2928. ConfiguredFailoverProxyProvider should not create a NameNode proxy
    with an underlying retry proxy. (Uma Maheswara Rao G via atm)
    
    HDFS-2955. IllegalStateException during standby startup in getCurSegmentTxId.
    (Hari Mankude via atm)
    
    HDFS-2937. TestDFSHAAdmin needs tests with MiniDFSCluster. (Brandon Li via
    suresh)
    
    HDFS-2586. Add protobuf service and implementation for HAServiceProtocol.
    (suresh via atm)
    
    HDFS-2952. NN should not start with upgrade option or with a pending an
    unfinalized upgrade. (atm)
    
    HDFS-2974. MiniDFSCluster does not delete standby NN name dirs during format.
    (atm)
    
    HDFS-2929. Stress test and fixes for block synchronization (todd)
    
    HDFS-2972. Small optimization building incremental block report (todd)
    
    HDFS-2973. Re-enable NO_ACK optimization for block deletion. (todd)
    
    HDFS-2922. HA: close out operation categories (eli)
    
    HDFS-2993. HA: BackupNode#checkOperation should permit CHECKPOINT operations
    (eli)
    
    HDFS-2904. Client support for getting delegation tokens. (todd)
    
    HDFS-3013. HA: NameNode format doesn't pick up
    dfs.namenode.name.dir.NameServiceId configuration (Mingjie Lai via todd)
    
    HDFS-3019. Fix silent failure of TestEditLogJournalFailures (todd)
    
    HDFS-2958. Sweep for remaining proxy construction which doesn't go through
    failover path. (atm)
    
    HDFS-2920. fix remaining TODO items. (atm and todd)
    
    HDFS-3027. Implement a simple NN health check. (atm)
    
    HDFS-3023. Optimize entries in edits log for persistBlocks call. (todd)
    
    HDFS-2979. Balancer should use logical uri for creating failover proxy with HA
    enabled. (atm)
    
    HDFS-3035. Fix failure of TestFileAppendRestart due to OP_UPDATE_BLOCKS (todd)
    
    HDFS-3039. Address findbugs and javadoc warnings on branch. (todd via atm)

Release 0.23.10 - UNRELEASED

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

    HDFS-5010. Reduce the frequency of getCurrentUser() calls from namenode
    (kihwal)

    HDFS-5346. Avoid unnecessary call to getNumLiveDataNodes() for each block 
    during IBR processing (Ravi Prakash via kihwal)

  OPTIMIZATIONS

  BUG FIXES

    HDFS-4998. TestUnderReplicatedBlocks fails intermittently (kihwal)

    HDFS-4329. DFSShell issues with directories with spaces in name (Cristina
    L. Abad via jeagles)

    HDFS-5526. Datanode cannot roll back to previous layout version (kihwal)

    HDFS-5557. Write pipeline recovery for the last packet in the block may
    cause rejection of valid replicas. (kihwal)

    HDFS-5558. LeaseManager monitor thread can crash if the last block is
    complete but another block is not. (kihwal)

Release 0.23.9 - 2013-07-08

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

  OPTIMIZATIONS

  BUG FIXES

    HDFS-4867. metaSave NPEs when there are invalid blocks in repl queue.
    (Plamen Jeliazkov and Ravi Prakash via shv)

    HDFS-4862. SafeModeInfo.isManual() returns true when resources are low even
    if it wasn't entered into manually (Ravi Prakash via kihwal)

    HDFS-4832. Namenode doesn't change the number of missing blocks in
    safemode when DNs rejoin or leave (Ravi Prakash via kihwal)

    HDFS-4878. On Remove Block, block is not removed from neededReplications
    queue. (Tao Luo via shv)

    HDFS-4205. fsck fails with symlinks. (jlowe)

Release 0.23.8 - 2013-06-05

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

    HDFS-4714. Log short messages in Namenode RPC server for exceptions 
    meant for clients. (kihwal)

  OPTIMIZATIONS

  BUG FIXES

    HDFS-4477. Secondary namenode may retain old tokens (daryn via kihwal)

    HDFS-4699. TestPipelinesFailover#testPipelineRecoveryStress fails
    sporadically (Chris Nauroth via kihwal)

    HDFS-4805. Webhdfs client is fragile to token renewal errors 
    (daryn via kihwal)

    HDFS-3875. Issue handling checksum errors in write pipeline. (kihwal)

    HDFS-4807. createSocketForPipeline() should not include timeout extension
    on connect. (Cristina L. Abad via kihwal)

Release 0.23.7 - 2013-04-08

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

  OPTIMIZATIONS

    HDFS-4532. RPC call queue may fill due to current user lookup (daryn)

  BUG FIXES

    HDFS-4288. NN accepts incremental BR as IBR in safemode (daryn via kihwal)

    HDFS-4495. Allow client-side lease renewal to be retried beyond soft-limit
    (kihwal)

    HDFS-4128. 2NN gets stuck in inconsistent state if edit log replay fails
    in the middle (kihwal via daryn)

    HDFS-4542. Webhdfs doesn't support secure proxy users (Daryn Sharp via
    kihwal)

    HDFS-4560. Webhdfs cannot use tokens obtained by another user (daryn)

    HDFS-4566. Webdhfs token cancelation should use authentication (daryn)

    HDFS-4567. Webhdfs does not need a token for token operations (daryn via
    kihwal)

    HDFS-4577. Webhdfs operations should declare if authentication is required
    (daryn via kihwal)

    HDFS-3344. Unreliable corrupt blocks counting in TestProcessCorruptBlocks
    (kihwal)

    HDFS-3367. WebHDFS doesn't use the logged in user when opening
    connections (daryn)

    HDFS-4581. checkDiskError should not be called on network errors (Rohit
    Kochar via kihwal)

    HDFS-4649. Webhdfs cannot list large directories (daryn via kihwal)

    HDFS-4548. Webhdfs doesn't renegotiate SPNEGO token (daryn via kihwal)

Release 0.23.6 - 2013-02-06

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

  OPTIMIZATIONS

  BUG FIXES

    HDFS-4247. saveNamespace should be tolerant of dangling lease (daryn)

    HDFS-4248. Renaming directories may incorrectly remove the paths in leases
    under the tree.  (daryn via szetszwo)

    HDFS-4385. Maven RAT plugin is not checking all source files (tgraves)

    HDFS-4426. Secondary namenode shuts down immediately after startup.
    (Arpit Agarwal via suresh)

Release 0.23.5 - 2012-11-28

  INCOMPATIBLE CHANGES

    HDFS-4080. Add a separate logger for block state change logs to enable turning
    off those logs. (Kihwal Lee via suresh)

  NEW FEATURES

  IMPROVEMENTS

  OPTIMIZATIONS

    HDFS-4075. Reduce recommissioning overhead (Kihwal Lee via daryn)

    HDFS-3990.  NN's health report has severe performance problems (daryn)

    HDFS-4181.  LeaseManager tries to double remove and prints extra messages
    (Kihwal Lee via daryn)

  BUG FIXES

    HDFS-3829. TestHftpURLTimeouts fails intermittently with JDK7  (Trevor
    Robinson via tgraves)

    HDFS-3824. TestHftpDelegationToken fails intermittently with JDK7 (Trevor
    Robinson via tgraves)

    HDFS-3224. Bug in check for DN re-registration with different storage ID
    (jlowe)

    HDFS-4090. getFileChecksum() result incompatible when called against
    zero-byte files. (Kihwal Lee via daryn)

    HDFS-4172. namenode does not URI-encode parameters when building URI for
    datanode request (Derek Dagit via bobby)

    HDFS-4182. SecondaryNameNode leaks NameCache entries (bobby)

    HDFS-4186. logSync() is called with the write lock held while releasing
    lease (Kihwal Lee via daryn)

Release 0.23.4

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

  OPTIMIZATIONS

  BUG FIXES

    HDFS-3831. Failure to renew tokens due to test-sources left in classpath
    (jlowe via bobby)

Release 0.23.3

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

    HDFS-2505. Add a test to verify getFileChecksum(..) with ViewFS.  (Ravi
    Prakash via szetszwo)

  OPTIMIZATIONS

  BUG FIXES

    HDFS-3166. Add timeout to Hftp connections.  (Daryn Sharp via szetszwo)

    HDFS-3176. Use MD5MD5CRC32FileChecksum.readFields() in JsonUtil .  (Kihwal
    Lee via szetszwo)

    HDFS-2652. Add support for host-based delegation tokens.  (Daryn Sharp via
    szetszwo)

    HDFS-3308. Uses canonical URI to select delegation tokens in HftpFileSystem
    and WebHdfsFileSystem.  (Daryn Sharp via szetszwo)

    HDFS-3312. In HftpFileSystem, the namenode URI is non-secure but the
    delegation tokens have to use secure URI.  (Daryn Sharp via szetszwo)

    HDFS-3318. Use BoundedInputStream in ByteRangeInputStream, otherwise, it
    hangs on transfers >2 GB.  (Daryn Sharp via szetszwo)

    HDFS-3321. Fix safe mode turn off tip message.  (Ravi Prakash via szetszwo)

    HDFS-3334. Fix ByteRangeInputStream stream leakage.  (Daryn Sharp via
    szetszwo)

    HDFS-3331. In namenode, check superuser privilege for setBalancerBandwidth
    and acquire the write lock for finalizeUpgrade.  (szetszwo)

    HDFS-3037. TestMulitipleNNDataBlockScanner#testBlockScannerAfterRestart is
    racy. (atm)

    HDFS-3577. In DatanodeWebHdfsMethods, use MessageBodyWriter instead of
    StreamingOutput, otherwise, it will fail to transfer large files.
    (szetszwo)

    HDFS-3646. LeaseRenewer can hold reference to inactive DFSClient
    instances forever. (Kihwal Lee via daryn)

    HDFS-3696. Set chunked streaming mode in WebHdfsFileSystem write operations
    to get around a Java library bug causing OutOfMemoryError.  (szetszwo)

    HDFS-3553. Hftp proxy tokens are broken (daryn)

    HDFS-3718. Datanode won't shutdown because of runaway DataBlockScanner
    thread (Kihwal Lee via daryn)

    HDFS-3861. Deadlock in DFSClient (Kihwal Lee via daryn)

    HDFS-3873. Hftp assumes security is disabled if token fetch fails (daryn)

    HDFS-3852. TestHftpDelegationToken is broken after HADOOP-8225 (daryn)

    HDFS-3890. filecontext mkdirs doesn't apply umask as expected
    (Tom Graves via daryn)

Release 0.23.2 - UNRELEASED

  INCOMPATIBLE CHANGES

    HDFS-2887. FSVolume, is a part of FSDatasetInterface implementation, should
    not be referred outside FSDataset.  A new FSVolumeInterface is defined.
    The BlockVolumeChoosingPolicy.chooseVolume(..) method signature is also
    updated.  (szetszwo)

  NEW FEATURES

    HDFS-2943. Expose last checkpoint time and transaction stats as JMX
    metrics. (atm)

  IMPROVEMENTS

    HDFS-2931. Switch DataNode's BlockVolumeChoosingPolicy to private-audience.
    (harsh via szetszwo)

    HDFS-2655. BlockReaderLocal#skip performs unnecessary IO. (Brandon Li 
    via jitendra)

    HDFS-2725. hdfs script usage information is missing the information 
    about "dfs" command (Prashant Sharma via stevel)

    HDFS-2907.  Add a conf property dfs.datanode.fsdataset.factory to make
    FSDataset in Datanode pluggable.  (szetszwo)

    HDFS-2985. Improve logging when replicas are marked as corrupt. (todd)

    HDFS-3098. Update and add tests for HADOOP-8173. (Daryn Sharp via szetszwo)

    HDFS-3104. Add tests for HADOOP-8175. (Daryn Sharp via szetszwo)

    HDFS-3066. Cap space usage of default log4j rolling policy.
    (Patrick Hunt via eli)

  OPTIMIZATIONS

    HDFS-3024. Improve performance of stringification in addStoredBlock (todd)

  BUG FIXES
    HDFS-2923. Namenode IPC handler count uses the wrong configuration key
    (todd)

    HDFS-2764. TestBackupNode is racy. (atm)

    HDFS-2869. Fix an error in the webhdfs docs for the mkdir op (harsh)

    HDFS-776.  Fix exception handling in Balancer.  (Uma Maheswara Rao G
    via szetszwo)

    HDFS-2815. Namenode sometimes oes not come out of safemode during 
    NN crash + restart. (Uma Maheswara Rao via suresh)

    HDFS-2950. Secondary NN HTTPS address should be listed as a
    NAMESERVICE_SPECIFIC_KEY. (todd)

    HDFS-2525. Race between BlockPoolSliceScanner and append. (Brandon Li
    via jitendra)

    HDFS-2938. Recursive delete of a large directory make namenode
    unresponsive. (Hari Mankude via suresh)

    HDFS-2969. ExtendedBlock.equals is incorrectly implemented (todd)

    HDFS-2944. Typo in hdfs-default.xml causes
    dfs.client.block.write.replace-datanode-on-failure.enable to be mistakenly
    disabled. (atm)

    HDFS-2981. In hdfs-default.xml, the default value of
    dfs.client.block.write.replace-datanode-on-failure.enable should be true.
    (szetszwo)

    HDFS-3008. Negative caching of local addrs doesn't work. (eli)

    HDFS-3006. In WebHDFS, when the return body is empty, set the Content-Type
    to application/octet-stream instead of application/json.  (szetszwo)

    HDFS-2991. Fix case where OP_ADD would not be logged in append(). (todd)

    HDFS-3012. Exception while renewing delegation token. (Bobby Evans via
    jitendra)

    HDFS-3032. Change DFSClient.renewLease() so that it only retries up to the
    lease soft-limit.  (Kihwal Lee via szetszwo)

    HDFS-2038. Update TestHDFSCLI to handle relative paths with globs.
    (Kihwal Lee via szetszwo)

    HDFS-3101. Cannot read empty file using WebHDFS.  (szetszwo)

    HDFS-3160. httpfs should exec catalina instead of forking it.
    (Roman Shaposhnik via eli)

Release 0.23.1 - 2012-02-17 

  INCOMPATIBLE CHANGES

  NEW FEATURES

    HDFS-2316. [umbrella] WebHDFS: a complete FileSystem implementation for 
    accessing HDFS over HTTP (szetszwo)

    HDFS-2594. Support getDelegationTokens and createSymlink in WebHDFS.
    (szetszwo)

    HDFS-2545. Change WebHDFS to support multiple namenodes in federation.
    (szetszwo)

    HDFS-2178. Contributing Hoop to HDFS, replacement for HDFS proxy
    with read/write capabilities. (tucu)


  IMPROVEMENTS
    HDFS-2560. Refactor BPOfferService to be a static inner class (todd)

    HDFS-2544. Hadoop scripts unconditionally source
    "$bin"/../libexec/hadoop-config.sh. (Bruno Mahé via tomwhite)

    HDFS-2543. HADOOP_PREFIX cannot be overridden. (Bruno Mahé via tomwhite)

    HDFS-2562. Refactor DN configuration variables out of DataNode class
    (todd)

    HDFS-2563. Some cleanup in BPOfferService. (todd)

    HDFS-2568. Use a set to manage child sockets in XceiverServer.
    (harsh via eli)

    HDFS-2454. Move maxXceiverCount check to before starting the
    thread in dataXceiver. (harsh via eli)

    HDFS-2570. Add descriptions for dfs.*.https.address in hdfs-default.xml.
    (eli)

    HDFS-2536. Remove unused imports. (harsh via eli)

    HDFS-2566. Move BPOfferService to be a non-inner class. (todd)

    HDFS-2552. Add Forrest doc for WebHDFS REST API.  (szetszwo)

    HDFS-2587. Add apt doc for WebHDFS REST API.  (szetszwo)

    HDFS-2604. Add a log message to show if WebHDFS is enabled and a
    configuration section in the forrest doc.  (szetszwo)

    HDFS-2511. Add dev script to generate HDFS protobufs. (tucu)

    HDFS-2654. Make BlockReaderLocal not extend RemoteBlockReader2. (eli)

    HDFS-2675. Reduce warning verbosity when double-closing edit logs
    (todd)

    HDFS-2335. DataNodeCluster and NNStorage always pull fresh entropy.
    (Uma Maheswara Rao G via eli)

    HDFS-2574. Remove references to some deprecated properties in conf
    templates and defaults files. (Joe Crobak via harsh)

    HDFS-2722. HttpFs should not be using an int for block size. (harsh)

    HDFS-2710. Add HDFS tests related to HADOOP-7933. (Siddarth Seth via
    suresh)

    HDFS-2349. Corruption detected during block transfers between DNs
    should log a WARN instead of INFO. (harsh)

    HDFS-2729. Update BlockManager's comments regarding the invalid block
    set (harsh)
 
    HDFS-2726. Fix a logging issue under DFSClient's createBlockOutputStream
    method (harsh)

    HDFS-554. Use System.arraycopy in BlockInfo.ensureCapacity. (harsh)
 
    HDFS-1314. Make dfs.blocksize accept size-indicating prefixes.
    (Sho Shimauchi via harsh)

    HDFS-69. Improve the 'dfsadmin' commandline help. (harsh)

    HDFS-2788. HdfsServerConstants#DN_KEEPALIVE_TIMEOUT is dead code. (eli)

    HDFS-362.  FSEditLog should not writes long and short as UTF8, and should
    not use ArrayWritable for writing non-array items.  (Uma Maheswara Rao G
    via szetszwo)

    HDFS-2803. Add logging to LeaseRenewer for better lease expiration debugging.
    (Jimmy Xiang via todd)

    HDFS-2817. Combine the two TestSafeMode test suites. (todd)

    HDFS-2818. Fix a missing space issue in HDFS webapps' title tags. (Devaraj K via harsh)

    HDFS-2397. Undeprecate SecondaryNameNode. (eli)

    HDFS-2814. NamenodeMXBean does not account for svn revision in the version 
    information. (Hitesh Shah via jitendra)

    HDFS-2784. Update hftp and hdfs for host-based token support.
    (Kihwal Lee via jitendra)

    HDFS-2785. Update webhdfs and httpfs for host-based token support.
    (Robert Joseph Evans via jitendra)

    HDFS-2868. Expose xceiver counts via the DataNode MXBean. (harsh)

    HDFS-2786. Fix host-based token incompatibilities in DFSUtil. (Kihwal
    Lee via jitendra)

    HDFS-208. name node should warn if only one dir is listed in dfs.name.dir.
    (Uma Maheswara Rao G via eli)

    HDFS-3139. Minor Datanode logging improvement. (eli)

  OPTIMIZATIONS

    HDFS-2130. Switch default checksum to CRC32C. (todd)

    HDFS-2533. Remove needless synchronization on some FSDataSet methods.
    (todd)

    HDFS-2129. Simplify BlockReader to not inherit from FSInputChecker.
    (todd)

    HDFS-2246. Enable reading a block directly from local file system
    for a client on the same node as the block file.  (Andrew Purtell,
    Suresh Srinivas and Jitendra Nath Pandey via szetszwo)

    HDFS-2825. Add test hook to turn off the writer preferring its local
    DN. (todd)

    HDFS-2826. Add test case for HDFS-1476 (safemode can initialize
    replication queues before exiting) (todd)

    HDFS-2864. Remove some redundant methods and the constant METADATA_VERSION
    from FSDataset.  (szetszwo)

    HDFS-2879. Change FSDataset to package private.  (szetszwo)

  BUG FIXES

    HDFS-2541. For a sufficiently large value of blocks, the DN Scanner 
    may request a random number with a negative seed value. (harsh via eli)

    HDFS-2502. hdfs-default.xml should include dfs.name.dir.restore.
    (harsh via eli)

    HDFS-2567. When 0 DNs are available, show a proper error when
    trying to browse DFS via web UI. (harsh via eli)

    HDFS-2575. DFSTestUtil may create empty files (todd)

    HDFS-2588. hdfs jsp pages missing DOCTYPE. (Dave Vronay via mattf)

    HDFS-2590. Fix the missing links in the WebHDFS forrest doc.  (szetszwo)

    HDFS-2596. TestDirectoryScanner doesn't test parallel scans. (eli)

    HDFS-2606. webhdfs client filesystem impl must set the content-type
    header for create/append. (tucu)

    HDFS-2614. hadoop dist tarball is missing hdfs headers. (tucu)
 
    HDFS-2653. DFSClient should cache whether addrs are non-local when
    short-circuiting is enabled. (eli)

    HDFS-2649. eclipse:eclipse build fails for hadoop-hdfs-httpfs.
    (Jason Lowe via eli)

    HDFS-2640. Javadoc generation hangs. (tomwhite)

    HDFS-2553. Fix BlockPoolSliceScanner spinning in a tight loop (Uma
    Maheswara Rao G via todd)

    HDFS-2658. HttpFS introduced 70 javadoc warnings. (tucu)

    HDFS-2706. Use configuration for blockInvalidateLimit if it is set.
    (szetszwo)

    HDFS-2646. Hadoop HttpFS introduced 4 findbug warnings. (tucu)

    HDFS-2657. TestHttpFSServer and TestServerWebApp are failing on trunk. (tucu)

    HDFS-2705. HttpFS server should check that upload requests have correct 
    content-type. (tucu)

    HDFS-2707. HttpFS should read the hadoop-auth secret from a file instead 
    inline from the configuration. (tucu)

    HDFS-2790. FSNamesystem.setTimes throws exception with wrong
    configuration name in the message. (Arpit Gupta via eli)

    HDFS-2810. Leases not getting renewed properly by clients (todd)

    HDFS-2751. Datanode may incorrectly drop OS cache behind reads
    even for short reads. (todd)

    HDFS-2816. Fix missing license header in httpfs findbugsExcludeFile.xml.
    (hitesh via tucu)

    HDFS-2822. processMisReplicatedBlock incorrectly identifies
    under-construction blocks as under-replicated. (todd)

    HDFS-442. dfsthroughput in test jar throws NPE (harsh)

    HDFS-2836. HttpFSServer still has 2 javadoc warnings in trunk.
    (revans2 via tucu)

    HDFS-2837. mvn javadoc:javadoc not seeing LimitedPrivate class.
    (revans2 via tucu)

    HDFS-2840. TestHostnameFilter should work with localhost or 
    localhost.localdomain (tucu)

    HDFS-2791. If block report races with closing of file, replica is
    incorrectly marked corrupt. (todd)

    HDFS-2827.  When the parent of a directory is the root, renaming the
    directory results in leases updated incorrectly.  (Uma Maheswara Rao G
    via szetszwo)

    HDFS-2835. Fix findbugs and javadoc issue with GetConf.java.
    (suresh)

    HDFS-2889. getNumCurrentReplicas is package private but should be public on
    0.23 (see HDFS-2408). (Gregory Chanan via atm)

    HDFS-2893. The start/stop scripts don't start/stop the 2NN when
    using the default configuration. (eli)

Release 0.23.0 - 2011-11-01 

  INCOMPATIBLE CHANGES

    HDFS-1526. Dfs client name for a map/reduce task should be unique
    among threads. (hairong)

    HDFS-1536. Improve HDFS WebUI. (hairong)

    HDFS-2210. Remove hdfsproxy. (eli)

    HDFS-1073. Redesign the NameNode's storage layout for image checkpoints
    and edit logs to introduce transaction IDs and be more robust.
    Please see HDFS-1073 section below for breakout of individual patches.

  NEW FEATURES

    HDFS-1359. Add BlockPoolID to Block. (suresh)

    HDFS-1365. Federation: propose ClusterID and BlockPoolID format 
    (Tanping via boryas)

    HDFS-1394. Federation: modify -format option for namenode to generated 
    new blockpool id and accept newcluster (boryas)

    HDFS-1400. Federation: DataTransferProtocol uses ExtendedBlockPool to 
    include BlockPoolID in the protocol. (suresh)

    HDFS-1428. Federation : add cluster ID and block pool ID into 
    Name node web UI(Tanping via boryas)

    HDFS-1450. Federation: Introduce block pool ID into FSDatasetInterface.
    (suresh)

    HDFS-1632. Federation: data node storage structure changes and
    introduce block pool storage. (Tanping via suresh)

    HDFS-1634. Federation: Convert single threaded DataNode into 
    per BlockPool thread model.(boryas)

    HDFS-1637. Federation: FSDataset in Datanode should be created after 
    initial handshake with namenode. (boryas and jitendra)

    HDFS-1653. Federation: Block received message from datanode sends invalid 
    DatanodeRegistration. (Tanping via suresh)

    HDFS-1645. Federation: DatanodeCommond.Finalize needs to include 
    BlockPoolId.  (suresh)

    HDFS-1638. Federation: DataNode.handleDiskError needs to inform 
    ALL namenodes if a disk failed (boryas)

    HDFS-1647. Federation: Multiple namenode configuration. (jitendra)

    HDFS-1639. Federation: Add block pool management to FSDataset. (suresh)

    HDFS-1648. Federation: Only DataStorage must be locked using in_use.lock 
    and no locks must be associated with BlockPoolStorage. (Tanping via suresh)

    HDFS-1641. Federation: Datanode fields that are no longer used should 
    be removed (boryas)

    HDFS-1642. Federation: add Datanode.getDNRegistration(String bpid) 
    method  (boryas)

    HDFS-1643. Federation: remove namenode argument from DataNode 
    constructor (boryas)

    HDFS-1657. Federation: Tests that corrupt block files fail due to changed 
    file path in federation. (suresh)

    HDFS-1661. Federation: Remove unnecessary TODO:FEDERATION comments.
    (jitendra)

    HDFS-1660. Federation: Datanode doesn't start with two namenodes (boryas)

    HDFS-1650. Federation: TestReplication fails. (Tanping via suresh)

    HDFS-1651. Federation: Tests fail due to null pointer exception in 
    Datnode#shutdown() method. (Tanping via suresh)

    HDFS-1649. Federation: Datanode command to refresh namenode list at 
    the datanode. (jitendra)

    HDFS-1646. Federation: MiniDFSClsuter#waitActive() waits for ever 
    with the introduction of BPOfferService in datanode. (suresh)

    HDFS-1659. Federation: BPOfferService exits after one iteration 
    incorrectly.  (Tanping via suresh)

    HDFS-1654. Federation: Fix TestDFSUpgrade and TestDFSRollback failures.
    (suresh)
    
    HDFS-1668. Federation: Datanodes sends block pool usage information 
    to the namenode in heartbeat. (suresh)

    HDFS-1669. Federation: Fix TestHftpFileSystem failure. (suresh)

    HDFS-1670. Federation: remove dnRegistration from Datanode (boryas)

    HDFS-1662. Federation: fix unit test case, TestCheckpoint 
    and TestDataNodeMXBean (tanping via boryas)

    HDFS-1671. Federation: shutdown in DataNode should be able to 
    shutdown individual BP threads as well as the whole DN (boryas).

    HDFS-1663. Federation: Rename getPoolId() everywhere to 
    getBlockPoolId() (tanping via boryas)

    HDFS-1652. FederationL Add support for multiple namenodes in 
    MiniDFSCluster. (suresh)

    HDFS-1672. Federation: refactor stopDatanode(name) to work 
    with multiple Block Pools (boryas)

    HDFS-1687. Federation: DirectoryScanner changes for 
    federation (Matt Foley via boryas)

    HDFS-1626. Make BLOCK_INVALIDATE_LIMIT configurable. (szetszwo)

    HDFS-1655. Federation: DatablockScanner should scan blocks for 
    all the block pools. (jitendra)

    HDFS-1664. Federation: Add block pool storage usage to Namenode WebUI.
    (Tanping via suresh)

    HDFS-1674. Federation: Rename BlockPool class to BlockPoolSlice. 
    (jghoman, Tanping via suresh)

    HDFS-1673. Federation: Datanode changes to track block token secret per 
    namenode. (suresh)

    HDFS-1677. Federation: Fix TestFsck and TestListCorruptFileBlocks 
    failures. (Tanping via suresh)

    HDFS-1678. Federation: Remove unnecessary #getBlockpool() 
    for NameNodeMXBean in FSNameSystem. (Tanping via Suresh)

    HDFS-1688. Federation: Fix failures in fault injection tests,
    TestDiskError, TestDatanodeRestart and TestDFSTartupVersions. (suresh)

    HDFS-1696. Federation: when build version doesn't match - 
    datanode should wait (keep connecting) untill NN comes up 
    with the right version (boryas)

    HDFS-1681. Balancer: support per pool and per node policies. (szetszwo)

    HDFS-1695. Federation: Fix testOIV and TestDatanodeUtils 
    (jhoman and tanping via boryas)

    HDFS-1699. Federation: Fix failure of TestBlockReport.
    (Matt Foley via suresh)

    HDFS-1698. Federation: TestOverReplicatedBlocks and TestWriteToReplica 
    failing. (jhoman and jitendra)

    HDFS-1701. Federation: Fix TestHeartbeathandling.
    (Erik Steffl and Tanping Wang via suresh)

    HDFS-1693. Federation: Fix TestDFSStorageStateRecovery failure. (suresh)

    HDFS-1694. Federation: SimulatedFSDataset changes to work with
    federation and multiple block pools. (suresh)

    HDFS-1689. Federation: Configuration for namenodes. (suresh and jitendra)

    HDFS-1682. Change Balancer CLI for multiple namenodes and balancing
    policy.  (szetszwo)

    HDFS-1697. Federation: fix TestBlockRecovery (boryas)

    HDFS-1702. Federation: fix TestBackupNode and TestRefreshNamendoes
    failures. (suresh)

    HDFS-1706. Federation: TestFileAppend2, TestFileAppend3 and 
    TestBlockTokenWithDFS failing. (jitendra)

    HDFS-1704. Federation: Add a tool that lists namenodes, secondary and
    backup from configuration file. (suresh)

    HDFS-1711. Federation: create method for updating machine name in 
    DataNode.java (boryas)

    HDFS-1712. Federation: when looking up datanode we should use machineNmae 
    (in testOverReplicatedBlocks) (boryas)

    HDFS-1709. Federation: Error "nnaddr url param is null" when clicking on a 
    node from NN Live Node Link. (jitendra)

    HDFS-1714. Federation: refactor upgrade object in DataNode (boryas) 

    HDFS-1715. Federation: warning/error not generated when datanode sees 
    inconsistent/different Cluster ID between namenodes (boryas)

    HDFS-1715. Federation: warning/error not generated when datanode sees 
    inconsistent/different Cluster ID between namenodes (boryas)

    HDFS-1716. Federation: Add decommission tests for federated namenodes.
    (suresh)

    HDFS-1713. Federation: Prevent DataBlockScanner from running in tight loop.
    (jitendra)

    HDFS-1721. Federation: Configuration for principal names should not be 
    namenode specific. (jitendra)

    HDFS-1717. Federation: FSDataset volumeMap access is not synchronized
    correctly. (suresh)

    HDFS-1722. Federation: Add flag to MiniDFSCluser to differentiate between
    federation and non-federation modes. (boryas via suresh)

    HDFS-1718. Federation: MiniDFSCluster#waitActive() bug causes some tests
    to fail. (suresh)

    HDFS-1719. Federation: Fix TestDFSRemove that fails intermittently.
    (suresh)

    HDFS-1720. Federation: FSVolumeSet volumes is not synchronized correctly.
    (suresh)

    HDFS-1700. Federation: fsck needs to work with federation changes.
    (Matt Foley via suresh)

    HDFS-1482. Add listCorruptFileBlocks to DistributedFileSystem.
    (Patrick Kling via hairong)

    HDFS-1448. Add a new tool Offline Edits Viewer (oev).  (Erik Steffl
    via szetszwo)

    HDFS-1735. Federation: merge FSImage change in federation to
    FSImage+NNStorage refactoring in trunk. (suresh)

    HDFS-1737. Federation: Update the layout version for federation
    changes. (suresh)

    HDFS-1744. Federation: Add new layout version to offline image viewer
    and edits viewer. (suresh)

    HDFS-1745. Federation: Fix fault injection test failures. (suresh)

    HDFS-1746. Federation: TestFileAppend3 fails intermittently. (jitendra)

    HDFS-1703. Improve start/stop scripts and add decommission tool for
    federation. (Tanping Wang, Erik Steffl via suresh)

    HDFS-1749. Federation: TestListCorruptFileBlocks failing in federation 
    branch. (jitendra)

    HDFS-1754. Federation: testFsck fails. (boryas)

    HDFS-1755. Federation: The BPOfferService must always connect to namenode
    as the login user. (jitendra)

    HDFS-1675. Support transferring RBW between datanodes. (szetszwo)

    HDFS-1791. Federation: Add command to delete block pool directories 
    from a datanode. (jitendra)

    HDFS-1761. Add a new DataTransferProtocol operation, Op.TRANSFER_BLOCK,
    for transferring RBW/Finalized with acknowledgement and without using RPC.
    (szetszwo)

    HDFS-1813. Federation: Authentication using BlockToken in RPC to datanode 
               fails. (jitendra)

    HDFS-1630. Support fsedits checksum. (hairong)

    HDFS-1606. Provide a stronger data guarantee in the write pipeline by
    adding a new datanode when an existing datanode failed.  (szetszwo)

    HDFS-1442. Api to get delegation token in Hdfs class. (jitendra)

    HDFS-1070. Speedup namenode image loading and saving by storing only
    local file names. (hairong)
    
    HDFS-1751. Intrinsic limits for HDFS files, directories (daryn via boryas).

    HDFS-1873. Federation: Add cluster management web console.
    (Tanping Wang via suresh)

    HDFS-1911 HDFS tests for the newly added viewfs

    HDFS-1814. Add "hdfs groups" command to query the server-side groups
    resolved for a user. (Aaron T. Myers via todd)

    HDFS-1914. Federation: namenode storage directories must be configurable
    specific to name service. (suresh)

    HDFS-1963. Create RPM and Debian packages for HDFS. Changes deployment
    layout to be consistent across the binary tgz, rpm, and deb.
    (Eric Yang via omalley)

    HDFS-2058. Change Data Transfer wire protocol to use protocol buffers.
    (todd)

    HDFS-2055. Add hflush support to libhdfs. (Travis Crawford via eli)
   
    HDFS-2083. Query JMX statistics over http via JMXJsonServlet. (tanping)

    HDFS-2156. Make hdfs and mapreduce rpm only depend on the same major 
    version for common and hdfs. (eyang via omalley)

    HDFS-2202. Add a new DFSAdmin command to set balancer bandwidth of
    datanodes without restarting.  (Eric Payne via szetszwo)

    HDFS-2284. Add a new FileSystem, webhdfs://, for supporting write Http
    access to HDFS.  (szetszwo)

    HDFS-2317. Support read access to HDFS in WebHDFS.  (szetszwo)

    HDFS-2338. Add configuration option to enable/disable WebHDFS.
    (jitendra via szetszwo)

    HDFS-2318. Provide authentication to WebHDFS using SPNEGO and delegation
    tokens.  (szetszwo)

    HDFS-2340. Support getFileBlockLocations and getDelegationToken in WebHDFS.
    (szetszwo)

    HDFS-2348. Support getContentSummary and getFileChecksum in WebHDFS.
    (szetszwo)

    HDFS-2385. Support renew and cancel delegation tokens in WebHDFS.
    (szetszwo)

    HDFS-2539. Support doAs and GETHOMEDIRECTORY in WebHDFS.
    (szetszwo)

  IMPROVEMENTS

    HDFS-1875. MiniDFSCluster hard-codes dfs.datanode.address to localhost
    (Eric Payne via mattf)

    HDFS-2019. Fix all the places where Java method File.list is used with
    FileUtil.list API (Bharath Mundlapudi via mattf)

    HDFS-1934. Fix NullPointerException when certain File APIs return null
    (Bharath Mundlapudi via mattf)

    HDFS-1510. Added test-patch.properties required by test-patch.sh (nigel)

    HDFS-1628. Display full path in AccessControlException.  (John George
    via szetszwo)

    HDFS-1707. Federation: Failure in browsing data on new namenodes. 
    (jitendra)

    HDFS-1683. Test Balancer with multiple NameNodes.  (szetszwo)

    HDFS-1547. Improve decommission mechanism. (suresh)

    HDFS-2143. Federation: In cluster web console, add link to namenode page
    that displays live and dead datanodes. (Ravi Prakash via suresh)

    HDFS-1588. Remove hardcoded strings for configuration keys, "dfs.hosts"
    and "dfs.hosts.exlude". (Erik Steffl via suresh)

    HDFS-1481. NameNode should validate fsimage before rolling. (hairong)

    HDFS-1506. Refactor fsimage loading code. (hairong)

    HDFS-1533. A more elegant FileSystem#listCorruptFileBlocks API
    (HDFS portion) (Patrick Kling via hairong)

    HDFS-1476. listCorruptFileBlocks should be functional while the
    name node is in safe mode. (Patrick Kling via hairong)

    HDFS-1534. Fix some incorrect logs in FSDirectory. (eli)
    
    HDFS-1539. A config option for the datanode to fsycn a block file
    when block is completely written. (dhruba)

    HDFS-1335. HDFS side change of HADDOP-6904: RPC compatibility. (hairong)

    HDFS-1557. Separate Storage from FSImage. (Ivan Kelly via jitendra)
    
    HDFS-560 Enhancements/tuning to hadoop-hdfs/build.xml

    HDFS-1629. Add a method to BlockPlacementPolicy for keeping the chosen
    nodes in the output array.  (szetszwo)

    HDFS-1731. Allow using a file to exclude certain tests from build (todd)

    HDFS-1736. Remove the dependency from DatanodeJspHelper to FsShell.
    (Daryn Sharp via szetszwo)
    
    HDFS-780. Revive TestFuseDFS. (eli)

    HDFS-1445. Batch the calls in DataStorage to FileUtil.createHardLink().
    (Matt Foley via jghoman)

    HDFS-1763. Replace hard-coded option strings with variables from
    DFSConfigKeys. (eli)

    HDFS-1541. Not marking datanodes dead when namenode in safemode.
    (hairong)

    HDFS-1120. Make DataNode's block-to-device placement policy pluggable
    (Harsh J Chouraria via todd)

    HDFS-1785. In BlockReceiver and DataXceiver, clientName.length() is used
    multiple times for determining whether the source is a client or a
    datanode.  (szetszwo)

    HDFS-1789. Refactor frequently used codes from DFSOutputStream and
    DataXceiver.  (szetszwo)

    HDFS-1767. Namenode ignores non-initial block report from datanodes
    when in safemode during startup. (Matt Foley via suresh)

    HDFS-1817. Move pipeline_Fi_[39-51] from TestFiDataTransferProtocol
    to TestFiPipelineClose.  (szetszwo)

    HDFS-1760. In FSDirectory.getFullPathName(..), it is better to return "/"
    for root directory instead of an empty string.  (Daryn Sharp via szetszwo)

    HDFS-1833. Reduce repeated string constructions and unnecessary fields,
    and fix comments in BlockReceiver.PacketResponder.  (szetszwo)

    HDFS-1486. Generalize CLITest structure and interfaces to faciliate
    upstream adoption (e.g. for web testing). (cos)

    HDFS-1844. Move "fs -help" shell command tests from HDFS to COMMOM; see
    also HADOOP-7230.  (Daryn Sharp via szetszwo)

    HDFS-1840. In DFSClient, terminate the lease renewing thread when all files
    being written are closed for a grace period, and start a new thread when
    new files are opened for write.  (szetszwo)

    HDFS-1854. make failure message more useful in
    DFSTestUtil.waitReplication(). (Matt Foley via eli)

    HDFS-1562. Add rack policy tests. (eli)
 
    HDFS-1856. TestDatanodeBlockScanner waits forever, errs without giving 
    information. (Matt Foley via eli)

    HDFS-1295. Improve namenode restart times by short-circuiting the
    first block reports from datanodes. (Matt Foley via suresh)
    Corrected merge error in DataNode.java. (Matt Foley)

    HDFS-1843. Discover file not found early for file append. 
    (Bharath Mundlapudi via jitendra)

    HDFS-1862. Improve test reliability of HDFS-1594. (Aaron T. Myers via eli)

    HDFS-1846. Preallocate edit log with OP_INVALID instead of zero bytes
    to ensure blocks are actually allocated. (Aaron T. Myers via todd)

    HDFS-1741. Provide a minimal pom file to allow integration of HDFS into Sonar
    analysis (cos)

    HDFS-1870. Move and rename DFSClient.LeaseChecker to a seperated class
    LeaseRenewer.  (szetszwo)

    HDFS-1866. Document dfs.datanode.max.transfer.threads in hdfs-default.xml
    (Harsh J Chouraria via todd)

    HDFS-1890. Improve the name, class and value type of the map
    LeaseRenewer.pendingCreates.  (szetszwo)

    HDFS-1865. Share LeaseRenewer among DFSClients so that there is only a
    LeaseRenewer thread per namenode per user.  (szetszwo)

    HDFS-1906. Remove logging exception stack trace in client logs when one of
    the datanode targets to read from is not reachable. (suresh)

    HDFS-1378. Edit log replay should track and report file offsets in case of
    errors. (Aaron T. Myers and Todd Lipcon via todd)

    HDFS-1917. Separate hdfs jars from common in ivy configuration.  (Eric Yang
    via szetszwo)

    HDFS-1899. GenericTestUtils.formatNamenode should be moved to DFSTestUtil
    (Ted Yu via todd)

    HDFS-1117. Metrics 2.0 HDFS instrumentation. (Luke Lu via suresh)

    HDFS-1946. HDFS part of HADOOP-7291. (eli)

    HDFS-1945. Removed the deprecated fields in DataTransferProtocol.
    (szetszwo)

    HDFS-1730. Use DaemonFactory from common and delete it from HDFS.
    (Tanping via suresh)

    HDFS-1573. Add useful tracing information to Lease Renewer thread names
    (todd)

    HDFS-1939. In ivy.xml, test conf should not extend common conf.
    (Eric Yang via szetszwo)

    HDFS-1332  Include more information in exceptions and debug messages
    when BlockPlacementPolicy cannot be satisfied.  (Ted Yu via szetszwo)

    HDFS-1958. Confirmation should be more lenient of user input when
    formatting the NameNode. (todd)

    HDFS-1905. Improve namenode -format command by not making -clusterId
    parameter mandatory. (Bharath Mundlapudi via suresh)

    HDFS-1877. Add a new test for concurrent read and write.  (CW Chung
    via szetszwo)

    HDFS-1959. Better error message for missing namenode directory. (eli)

    HDFS-1996. ivy: hdfs test jar should be independent to common test jar.
    (Eric Yang via szetszwo)

    HDFS-1812. TestHDFSCLI should clean up cluster in teardown method.
    (Uma Maheswara Rao G via todd)

    HDFS-1884. Improve TestDFSStorageStateRecovery to properly throw in the
    case of errors. (Aaron T. Myers via todd)

    HDFS-1727. fsck command should display command usage if user passes any
    illegal argument. (Sravan Kumar via todd)

    HDFS-1636. If dfs.name.dir points to an empty dir, namenode format
    shouldn't require confirmation. (Harsh J Chouraria via todd)

    HDFS-1966. Encapsulate individual DataTransferProtocol op headers.
    (szetszwo)

    HDFS-2024. Format TestWriteRead source codes.  (CW Chung via szetszwo)

    HDFS-1968. Enhance TestWriteRead to support position/sequential read,
    append, truncate and verbose options.  (CW Chung via szetszwo)

    HDFS-1986. Add option to get http/https address from 
    DFSUtil#getInfoServer(). (Tanping via suresh)

    HDFS-2029. In TestWriteRead, check visible length immediately after
    openning the file and fix code style.  (John George via szetszwo)

    HDFS-2040. Only build libhdfs if a flag is passed. (eli)

    HDFS-1586. Add InterfaceAudience and InterfaceStability annotations to 
    MiniDFSCluster. (suresh)

    HDFS-2003. Separate FSEditLog reading logic from edit log memory state
    building logic. (Ivan Kelly via todd)

    HDFS-2066. Create a package and individual class files for
    DataTransferProtocol.  (szetszwo)

    HADOOP-7106. Reorganize project SVN layout to "unsplit" the projects.
    (todd, nigel)

    HDFS-2046. Force entropy to come from non-true random for tests. (todd)

    HDFS-2073. Add @Override annotation to NameNode. (suresh)

    HDFS-420. Fuse-dfs should cache fs handles. (Brian Bockelman and eli)

    HDFS-1568. Improve the log messages in DataXceiver.  (Joey Echeverria via
    szetszwo)

    HDFS-2100. Improve TestStorageRestore. (atm)

    HDFS-2092. Remove some object references to Configuration in DFSClient.
    (Bharath Mundlapudi via szetszwo)

    HDFS-2087. Declare methods in DataTransferProtocol interface, and change
    Sender and Receiver to implement the interface.  (szetszwo)

    HDFS-1723. quota errors messages should use the same scale. (Jim Plush via
    atm)

    HDFS-2110. StreamFile and ByteRangeInputStream cleanup. (eli)

    HDFS-2107. Move block management code from o.a.h.h.s.namenode to a new
    package o.a.h.h.s.blockmanagement.  (szetszwo)

    HDFS-2109. Store uMask as member variable to DFSClient.Conf.  (Bharath
    Mundlapudi via szetszwo)

    HDFS-2111. Add tests for ensuring that the DN will start with a few bad
    data directories. (Harsh J Chouraria via todd)

    HDFS-2134. Move DecommissionManager to the blockmanagement package.
    (szetszwo)

    HDFS-1977. Stop using StringUtils.stringifyException(). 
    (Bharath Mundlapudi via jitendra)

    HDFS-2131. Add new tests for the -overwrite/-f option in put and
    copyFromLocal by HADOOP-7361.  (Uma Maheswara Rao G via szetszwo)

    HDFS-2140. Move Host2NodesMap to the blockmanagement package.  (szetszwo)

    HDFS-2154. In TestDFSShell, use TEST_ROOT_DIR and fix some deprecated
    warnings.  (szetszwo)

    HDFS-2153. Move DFSClientAdapter to test and fix some javac warnings in
    OfflineEditsViewerHelper.  (szetszwo)

    HDFS-2159. Deprecate DistributedFileSystem.getClient() and fixed the
    deprecated warnings in DFSAdmin.  (szetszwo)

    HDFS-2157. Improve header comment in o.a.h.hdfs.server.namenode.NameNode.
    (atm via eli)

    HDFS-2147. Move cluster network topology to block management and fix some
    javac warnings.  (szetszwo)

    HDFS-2141. Remove NameNode roles Active and Standby (they become
    states of the namenode). (suresh)

    HDFS-2161. Move createNamenode(..), createClientDatanodeProtocolProxy(..)
    and Random object creation to DFSUtil; move DFSClient.stringifyToken(..)
    to DelegationTokenIdentifier.  (szetszwo)

    HDFS-1774. Small optimization to FSDataset. (Uma Maheswara Rao G via eli)

    HDFS-2167.  Move dnsToSwitchMapping and hostsReader from FSNamesystem to
    DatanodeManager.  (szetszwo)

    HDFS-2116. Use Mokito in TestStreamFile and TestByteRangeInputStream.
    (Plamen Jeliazkov via shv)

    HDFS-2112.  Move ReplicationMonitor to block management.  (Uma Maheswara
    Rao G via szetszwo)

    HDFS-1739.  Add available volume size to the error message when datanode
    throws DiskOutOfSpaceException.  (Uma Maheswara Rao G via szetszwo)

    HDFS-2144. If SNN shuts down during initialization it does not log the
    cause. (Ravi Prakash via atm)

    HDFS-2180. Refactor NameNode HTTP server into new class. (todd)
    
    HDFS-2198. Remove hardcoded configuration keys. (suresh)

    HDFS-2149. Move EditLogOp serialization formats into FsEditLogOp
    implementations. (Ivan Kelly via todd)

    HDFS-2191. Move datanodeMap from FSNamesystem to DatanodeManager.
    (szetszwo)

    HDFS-2200. Change FSNamesystem.LOG to package private. (szetszwo)

    HDFS-2195. Refactor StorageDirectory to not be an non-static inner class.
    (todd via eli)

    HDFS-2212. Refactor double-buffering code out of EditLogOutputStreams.
    (todd via eli)

    HDFS-2199. Move blockTokenSecretManager from FSNamesystem to BlockManager.
    (Uma Maheswara Rao G via szetszwo)

    HDFS-2187. Make EditLogInputStream act like an iterator over FSEditLogOps
    (Ivan Kelly and todd via todd)

    HDFS-2225. Refactor edit log file management so it's not in classes
    which should be generic to the type of edit log storage. (Ivan Kelly
    via todd)

    HDFS-2108. Move datanode heartbeat handling from namenode package to
    blockmanagement package.  (szetszwo)

    HDFS-2226. Clean up counting of operations in FSEditLogLoader (todd)

    HDFS-2228. Move block and datanode code from FSNamesystem to
    BlockManager and DatanodeManager.  (szetszwo)

    HDFS-2238. In NamenodeFsck.toString(), uses StringBuilder.(..) instead of
    string concatenation.  (Uma Maheswara Rao G via szetszwo)
   
    HDFS-2230. ivy to resolve/retrieve latest common-tests jar published by 
    hadoop common maven build. (gkesavan)

    HDFS-2227. getRemoteEditLogManifest should pull its information from
    FileJournalManager during checkpoint process (Ivan Kelly and Todd Lipcon
    via todd)

    HDFS-2239. Reduce access levels of the fields and methods in FSNamesystem.
    (szetszwo)

    HDFS-2241. Remove implementing FSConstants interface to just get the
    constants from the interface. (suresh)

    HDFS-2237. Change UnderReplicatedBlocks from public to package private.
    (szetszwo)

    HDFS-2233. Add WebUI tests with URI reserved chars. (eli)

    HDFS-2265. Remove unnecessary BlockTokenSecretManager fields/methods from
    BlockManager.  (szetszwo)

    HDFS-2260. Refactor BlockReader into an interface and implementation.
    (todd)

    HDFS-2096. Mavenization of hadoop-hdfs (Alejandro Abdelnur via tomwhite)

    HDFS-2273.  Refactor BlockManager.recentInvalidateSets to a new class.
    (szetszwo)

    HDFS-2266.  Add Namesystem and SafeMode interfaces to avoid directly
    referring to FSNamesystem in BlockManager. (szetszwo)

    HDFS-1217.  Change some NameNode methods from public to package private.
    (Laxman via szetszwo)

    HDFS-1620. Rename HdfsConstants -> HdfsServerConstants, FSConstants ->
               HdfsConstants. (Harsh J Chouraria via atm)

    HDFS-2197. Refactor RPC call implementations out of NameNode class (todd)

    HDFS-2332. Add test for HADOOP-7629 (using an immutable FsPermission
    object as an RPC parameter fails). (todd)

    HDFS-2363. Move datanodes size printing from FSNamesystem.metasave(..)
    to BlockManager.  (Uma Maheswara Rao G via szetszwo)

    HDFS-2209. Make MiniDFS easier to embed in other apps. (stevel)

    HDFS-2205. Log message for failed connection to datanode is not
    followed by a success message. (Ravi Prakash via stevel)

    HDFS-2401. Running a set of methods in a Single Test Class.
    (Jonathan Eagles via mahadev)

    HDFS-2471. Add federation documentation. (suresh)

    HDFS-2485. Improve code layout and constants in UnderReplicatedBlocks
    (stevel)

    HDFS-2356.  Support case insensitive query parameter names in WebHDFS.
    (szetszwo)

    HDFS-2368.  Move SPNEGO conf properties from hdfs-default.xml to
    hdfs-site.xml.  (szetszwo)

    HDFS-2395. Add a root element in the JSON responses of WebHDFS.
    (szetszwo)

    HDFS-2427. Change the default permission in WebHDFS to 755 and add range
    check/validation for all parameters.  (szetszwo)

    HDFS-2501. Add version prefix and root methods to WebHDFS.  (szetszwo)

    HDFS-1869. mkdirs should use the supplied permission for all of the created
    directories. (Daryn Sharp via szetszwo)

    HDFS-2355. Federation: enable using the same configuration file across 
    all the nodes in the cluster. (suresh)

    HDFS-2371. Refactor BlockSender.java for better readability. (suresh)

    HDFS-2493. Remove reference to FSNamesystem in blockmanagement classes.
    (szetszwo)

    HDFS-2294. Download of commons-daemon TAR should not be under target (tucu)

    HDFS-2322. the build fails in Windows because commons-daemon TAR cannot be
    fetched. (tucu)

    HDFS-2436. Change FSNamesystem.setTimes(..) for allowing setting times on
    directories.  (Uma Maheswara Rao G via szetszwo)

    HDFS-2512. Add textual error message to data transfer protocol responses
    (todd)

    HDFS-2521. Remove custom checksum headers from data transfer protocol
    (todd)

    HDFS-2308. NamenodeProtocol.endCheckpoint is vestigial and can be removed.
    (eli)

    HDFS-2507. Allow saveNamespace operations to be canceled. (todd)

  OPTIMIZATIONS

    HDFS-1458. Improve checkpoint performance by avoiding unnecessary image
    downloads and loading. (hairong)

    HDFS-1601. Pipeline ACKs are sent as lots of tiny TCP packets (todd)

    HDFS-1826. NameNode should save image to name directories in parallel
    during upgrade. (Matt Foley via hairong)

    HDFS-2030. Improve usability of namenode -upgrade command.
    (Bharath Mundlapudi via suresh)

    HDFS-2056. Update fetchdt usage. (Tanping Wang via jitendra)

    HDFS-2118. Couple dfs data dir improvements. (eli)

    HDFS-2500. Avoid file system operations in BPOfferService thread while
    processing deletes. (todd)

    HDFS-2465. Add HDFS support for fadvise readahead and drop-behind. (todd)

  BUG FIXES

    HDFS-2344. Fix the TestOfflineEditsViewer test failure in 0.23 branch.
    (Uma Maheswara Rao G via mattf)

    HDFS-2347. Fix checkpointTxnCount's comment about editlog size. 
    (Uma Maheswara Rao G via mattf)

    HDFS-2011. Removal and restoration of storage directories on checkpointing
    failure doesn't work properly. (Ravi Prakash via mattf)

    HDFS-1955. FSImage.doUpgrade() was made too fault-tolerant by HDFS-1826.
    (mattf)

    HDFS-2061. Two minor bugs in BlockManager block report processing. (mattf)

    HDFS-1449. Fix test failures - ExtendedBlock must return 
    block file name in #getBlockName(). (suresh)

    HDFS-1680. Fix TestBalancer. (szetszwo)

    HDFS-1705. Balancer command throws NullPointerException. (suresh via
    szetszwo)

    HDFS-1559. Add missing UGM overrides to TestRefreshUserMappings
    (Todd Lipcon via eli)

    HDFS-1585. Fix build after HDFS-1547 (todd)

    HDFS-1684. Balancer cannot start with with multiple namenodes.  (szetszwo)

    HDFS-1516. mvn-install is broken after 0.22 branch creation. (cos)

    HDFS-1360. TestBlockRecovery should bind ephemeral ports.
    (Todd Lipcon via hairong)

    HDFS-1551. Fix pom templates dependency list (gkesavan)

    HDFS-1509. A savenamespace command writes the fsimage and edits into
    all configured directories. (dhruba)

    HDFS-1540. Make Datanode handle errors from RPC calls to namenode
    more elegantly. (dhruba)

    HDFS-1463. Accesstime of a file is not updated in safeMode. (dhruba)

    HDFS-863. Potential deadlock in TestOverReplicatedBlocks. 
    (Ken Goodhope via jghoman)

    HDFS-1607. Fix referenced to misspelled method name getProtocolSigature
    (todd)

    HDFS-1610. Fix TestClientProtocolWithDelegationToken and TestBlockToken
    on trunk after HADOOP-6904 (todd)

    HDFS-1600. Fix release audit warnings on trunk. (todd)

    HDFS-1691. Remove a duplicated static initializer for reading default
    configurations in DFSck.  (Alexey Diomin via szetszwo)

    HDFS-1748. Balancer utilization classification is incomplete.  (szetszwo)

    HDFS-1738. change hdfs jmxget to return an empty string instead of 
    null when an attribute value is not available (tanping vi boryas)

    HDFS-1757. Don't compile fuse-dfs by default. (eli)

    HDFS-1770. TestFiRename fails due to invalid block size. (eli)

    HDFS-1797. Fix new findbugs warning introduced by HDFS-1120 (todd)

    HDFS-1611. Fix up some log messages in DFSClient and MBean registration
    (Uma Maheswara Rao G via todd)

    HDFS-1543. Reduce dev. cycle time by moving system testing artifacts from
    default build and push to maven for HDFS (Luke Lu via cos)

    HDFS-1818. TestHDFSCLI is failing on trunk after HADOOP-7202.
    (Aaron T. Myers via todd)

    HDFS-1828. TestBlocksWithNotEnoughRacks intermittently fails assert.
    (Matt Foley via eli)

    HDFS-1824. delay instantiation of file system object until it is
     needed (linked to HADOOP-7207) (boryas)

    HDFS-1831. Fix append bug in FileContext and implement CreateFlag
    check (related to HADOOP-7223). (suresh)

    HDFS-1594. When the disk becomes full Namenode is getting shutdown and 
    not able to recover. (Aaron T. Myers via eli)

    HDFS-1822. Handle editlog opcode conflict with 0.20.203 during upgrade,
    by throwing an error to indicate the editlog needs to be empty.
    (suresh)

    HDFS-1808. TestBalancer waits forever, errs without giving information.
    (Matt Foley via eli)

    HDFS-1829. TestNodeCount waits forever, errs without giving information.
    (Matt Foley via eli)

    HDFS-1860. when renewing/canceling DelegationToken over http we need to
     pass exception information back to the caller.(boryas)

    HDFS-1871. Mapreduce build fails due to MiniDFSCluster change from
    HDFS-1052. (suresh)

    HDFS-1876. One MiniDFSCluster constructor ignores numDataNodes parameter
    (todd)

    HDFS-1773. Do not show decommissioned datanodes, which are not in both
    include and exclude lists, on web and JMX interfaces.
    (Tanping Wang via szetszwo)

    HDFS-1888. MiniDFSCluster#corruptBlockOnDatanodes() access must be
    public. (suresh)

    HDFS-1889. incorrect path in start/stop dfs script. (John George via eli)

    HDFS-1891. Disable IPV6 for junit tests to fix TestBackupNode failure.
    (suresh)

    HDFS-1898. Tests failing on trunk due to use of NameNode.format.
    (todd via eli)

    HDFS-1902. Fix setrep path display for TestHDFSCLI.  (Daryn Sharp
    via szetszwo)

    HDFS-1827. Fix timeout problem in TestBlockReplacement.  (Matt Foley
    via szetszwo)

    HDFS-1908. Fix a NullPointerException in fi.DataTransferTestUtil.
    (szetszwo)

    HDFS-1912. Update tests for FsShell standardized error messages.
    (Daryn Sharp via szetszwo)

    HDFS-1903. Fix path display for rm/rmr in TestHDFSCLI and TestDFSShell.
    (Daryn Sharp via szetszwo)

    HDFS-1627. Fix NullPointerException in Secondary NameNode. (hairong)

    HDFS-1928. Fix path display for touchz in TestHDFSCLI.
    (Daryn Sharp via todd)

    HDFS-1938. Fix ivy-retrieve-hdfs dependence in build.xml and aop.xml.
    (Eric Yang via szetszwo)

    HDFS-1929. TestEditLogFileOutputStream fails if running on same host as NN
    (Aaron T. Myers via todd)

    HDFS-1933. Update TestDFSShell for improved "test" shell command. (Daryn
    Sharp via todd)
    
    HDFS-1931. Update TestDFSShell for improved "du" shell command. (Daryn
    Sharp via todd)

    HDFS-1439. HDFS Federation: Fix compilation error in TestFiHftp. (suresh)

    HDFS-1881. Federation: after taking snapshot the current directory 
    of datanode is empty. (Tanping Wang via suresh)

    HDFS-1927. Fix a bug which causes ip=null in NameNode audit log.
    (John George via szetszwo)

    HDFS-1953. Federation: Change name node mxbean name in cluster web 
    console. (Tanping Wang via suresh)

    HDFS-1922. Fix recurring failure of TestJMXGet (Luke Lu via todd)

    HDFS-1371. One bad node can incorrectly flag many files as corrupt.
    (Tanping Wang via jitendra)

    HDFS-1943. Fail to start datanode while start-dfs.sh is executed by 
    root user. (Wei Yongjun via jghoman)

    HDFS-1983. Fix path display for copy and rm commands in TestHDFSCLI and
    TestDFSShell. (Daryn Sharp via todd)

    HDFS-1999. Tests use deprecated configs. (Aaron T. Myers via eli)

    HDFS-1592. Datanode startup doesn't honor volumes.tolerated. 
    (Bharath Mundlapudi via jitendra)

    HDFS-1920. libhdfs does not build for ARM processors.
    (Trevor Robinson via eli)

    HDFS-1936. Layout version change from HDFS-1822 causes upgrade failure.
    (suresh)

    HDFS-2021. Update numBytesAcked before sending the ack in PacketResponder.
    (John George via szetszwo)

    HDFS-2020. Fix TestDFSUpgradeFromImage by removing the use of DataNode
    as a singleton. (suresh via todd)

    HDFS-2022. ant binary should build libhdfs. (Eric Yang via eli)

    HDFS-2014. Change HDFS scripts to work in developer enviroment post
    RPM packaging changes. (Eric Yang via suresh)

    HDFS-1995. Federation: Minor bug fixes and modification cluster web UI.
    (Tanping Wang via suresh)

    HDFS-1907. Fix position read for reading still-being-written file in
    DFSInputStream.  (John George via szetszwo)

    HDFS-1923. In TestFiDataTransferProtocol2, reduce random sleep time period
    and increase the number of datanodes.  (szetszwo)

    HDFS-1149. Lease reassignment should be persisted to the edit log.
    (Aaron T. Myers via todd)

    HDFS-1998. Federation: Make refresh-namenodes.sh refresh all the
    namenode. (Tanping Wang via suresh)

    HDFS-2041. OP_CONCAT_DELETE doesn't properly restore modification time
    of the concatenated file when edit logs are replayed. (todd)

    HDFS-2063. libhdfs test is broken. (Eric Yang via eli)

    HDFS-2067. Bump DATA_TRANSFER_VERSION constant in trunk after introduction
    of protocol buffers in the protocol. (szetszwo via todd)

    HDFS-2069. Incorrect default trash interval value in the docs.
    (Harsh J Chouraria via eli)

    HDFS-1942. Datanode must exist when all the block pool service threads
    exit. (Bharath Mundlapudi via suresh)

    HDFS-1656. Fixes an issue to do with fetching of delegation tokens in
    HftpFileSystem. Contributed by Kan Zhang.

    HDFS-1692. In secure mode, Datanode process doesn't exit when disks 
    fail. (Bharath Mundlapudi via suresh)

    HDFS-1734. 'Chunk size to view' option is not working in Name Node UI.
    (Uma Maheswara Rao G via jitendra)

    HDFS-2086. If the include hosts list contains host names, after restarting
    namenode, data nodes registration is denied.  Contributed by Tanping Wang.

    HDFS-2082. SecondaryNameNode web interface doesn't show the right info. (atm)

    HDFS-1321. If service port and main port are the same, there is no clear
    log message explaining the issue. (Jim Plush via atm)

    HDFS-1381. HDFS javadocs hard-code references to dfs.namenode.name.dir and
    dfs.datanode.data.dir parameters (Jim Plush via atm)

    HDFS-2053. Bug in INodeDirectory#computeContentSummary warning.
    (Michael Noll via eli)

    HDFS-1990. Fix resource leaks in BlockReceiver.close().  (Uma Maheswara
    Rao G via szetszwo)

    HDFS-2034. Length in DFSInputStream.getBlockRange(..) becomes -ve when
    reading only from a currently being written block. (John George via
    szetszwo)

    HDFS-2132. Potential resource leak in EditLogFileOutputStream.close. (atm)

    HDFS-2120. on reconnect, DN can connect to NN even with different source
    versions. (John George via atm)

    HDFS-2152. TestWriteConfigurationToDFS causing the random failures. (Uma
    Maheswara Rao G via atm)

    HDFS-2114. re-commission of a decommissioned node does not delete 
    excess replicas. (John George via mattf)

    HDFS-1776. Bug in Concat code. (Bharath Mundlapudi via Dmytro Molkov)

    HDFS-2196. Make ant build system work with hadoop-common JAR generated
    by Maven. (Alejandro Abdelnur via tomwhite)

    HDFS-2245. Fix a NullPointerException in BlockManager.chooseTarget(..).
    (szetszwo)

    HDFS-2229. Fix a deadlock in namenode by enforcing lock acquisition
    ordering.  (szetszwo)

    HDFS-2235. Encode servlet paths. (eli)

    HDFS-2186. DN volume failures on startup are not counted. (eli)

    HDFS-2240. Fix a deadlock in LeaseRenewer by enforcing lock acquisition
    ordering.  (szetszwo)

    HDFS-73. DFSOutputStream does not close all the sockets.
    (Uma Maheswara Rao G via eli)

    HDFS-1257. Fix a race condition on BlockManager.recentInvalidateSets.
    (Eric Payne via szetszwo)

    HDFS-2267. DataXceiver thread name incorrect while waiting on op during
    keepalive. (todd)

    HDFS-1480. All replicas of a block can end up on the same rack when
    some datanodes are decommissioning. (todd)

    HDFS-2286. DataXceiverServer logs AsynchronousCloseException at shutdown
    (todd)

    HDFS-2289. Ensure jsvc is bundled with the HDFS distribution artifact.
    (Alejandro Abdelnur via acmurthy) 

    HDFS-2314. MRV1 test compilation broken after HDFS-2197 (todd)

    HDFS-2323. start-dfs.sh script fails for tarball install (tomwhite)

    HDFS-2346. TestHost2NodesMap & TestReplicasMap will fail depending upon
               execution order of test methods (Laxman via atm)

    HDFS-2345. TestLeaseRecovery2 fails on 0.23 branch (Uma Maheswara Rao G
               via atm)

    HDFS-2412. Add backwards-compatibility layer for renamed FSConstants
               class (todd)

    HDFS-2414. Fix TestDFSRollback to avoid spurious failures. (todd)

    HDFS-2422. The NN should tolerate the same number of low-resource volumes
               as failed volumes (atm)

    HDFS-2467. HftpFileSystem uses incorrect compare for finding delegation
    tokens. (omalley)

    HDFS-2331. Fix WebHdfsFileSystem compilation problems for a bug in JDK
    version < 1.6.0_26.  (Abhijit Suresh Shingate via szetszwo)

    HDFS-2333. Change DFSOutputStream back to package private, otherwise,
    there are two SC_START_IN_CTOR findbugs warnings.  (szetszwo)

    HDFS-2366. Initialize WebHdfsFileSystem.ugi in object construction.
    (szetszwo)

    HDFS-2361. hftp is broken, fixed username checks in JspHelper. (jitendra)

    HDFS-2403. NamenodeWebHdfsMethods.generateDelegationToken(..) does not use
    the renewer parameter.  (szetszwo)

    HDFS-2409. _HOST in dfs.web.authentication.kerberos.principal. (jitendra)

    HDFS-2404. WebHDFS liststatus json response is not correct. (suresh)

    HDFS-2441. Remove the Content-Type set by HttpServer.QuotingInputFilter in
    WebHDFS responses.  (szetszwo)

    HDFS-2428. Convert com.sun.jersey.api.ParamException$QueryParamException
    to IllegalArgumentException and response it as http BAD_REQUEST in WebHDFS.
    (szetszwo)

    HDFS-2424. Added a root element "HdfsFileStatuses" for the response
    of WebHDFS listStatus.  (szetszwo)

    MAPREDUCE-2764. Fix renewal of dfs delegation tokens. (Owen via jitendra)

    HDFS-2439. Fix NullPointerException in WebHDFS when opening a non-existing
    file or creating a file without specifying the replication parameter.
    (szetszwo)

    HDFS-2453. Fix http response code for partial content in WebHDFS, added
    getDefaultBlockSize() and getDefaultReplication() in WebHdfsFileSystem
    and cleared content type in ExceptionHandler.  (szetszwo)

    HDFS-2411. The the auth to local mappings are not being respected, with 
    WebHDFS enabled. (jitendra)

    HDFS-2494. Close the streams and DFSClient in DatanodeWebHdfsMethods.
    (Uma Maheswara Rao G via szetszwo)

    HDFS-2298. Fix TestDfsOverAvroRpc by changing ClientProtocol to
    not include multiple methods of the same name. (cutting)

    HDFS-2432. WebHDFS: response FORBIDDEN when setReplication on non-files;
    clear umask before creating a flie; throw IllegalArgumentException if
    setOwner with both owner and group empty; throw FileNotFoundException if
    getFileStatus on non-existing files; fix bugs in getBlockLocations; and
    changed getFileChecksum json response root to "FileChecksum".  (szetszwo)

    HDFS-2065. Add null checks in DFSClient.getFileChecksum(..).  (Uma
    Maheswara Rao G via szetszwo)

    HDFS-2522. Disable TestDfsOverAvroRpc test. (suresh)

    HDFS-2416. distcp with a WebHDFS uri on a secure cluster fails. (jitendra)

    HDFS-2527. WebHDFS: remove the use of "Range" header in Open; use ugi
    username if renewer parameter is null in GetDelegationToken; response OK
    when setting replication for non-files; rename GETFILEBLOCKLOCATIONS to
    GET_BLOCK_LOCATIONS and state that it is a private unstable API; replace
    isDirectory and isSymlink with enum {FILE, DIRECTORY, SYMLINK} in
    HdfsFileStatus JSON object.  (szetszwo)

    HDFS-2528. WebHDFS: set delegation kind to WEBHDFS and add a HDFS token
    when http requests are redirected to datanode.  (szetszwo)

    HDFS-2540. WebHDFS: change "Expect: 100-continue" to two-step write; change 
    "HdfsFileStatus" and "localName" respectively to "FileStatus" and
    "pathSuffix" in JSON response.  (szetszwo)

  BREAKDOWN OF HDFS-1073 SUBTASKS

    HDFS-1521. Persist transaction ID on disk between NN restarts.
               (Ivan Kelly and Todd Lipcon via todd)

    HDFS-1538. Refactor more startup and image loading code out of FSImage.
               (todd)

    HDFS-1729. Add code to detect valid length of an edits file. (todd)

    HDFS-1793. Add code to inspect a storage directory with txid-based
               filenames (todd)

    HDFS-1794. Add code to list which edit logs are available on a remote NN
               (todd)

    HDFS-1858. Add state management variables to FSEditLog (Ivan Kelly and Todd
               Lipcon via todd)

    HDFS-1859. Add some convenience functions to iterate over edit log streams
               (Ivan Kelly and Todd Lipcon via todd)

    HDFS-1894. Add constants for LAYOUT_VERSIONs in edits log branch (todd)

    HDFS-1892. Fix EditLogFileInputStream.getValidLength to be aware of
               OP_INVALID filler (todd)

    HDFS-1799. Refactor log rolling and filename management out of FSEditLog
               (Ivan Kelly and Todd Lipcon via todd)

    HDFS-1801. Remove use of timestamps to identify checkpoints and logs (todd)

    HDFS-1930. TestDFSUpgrade failing in HDFS-1073 branch (todd)

    HDFS-1800. Extend image checksumming to function with multiple fsimage
               files per directory. (todd)

    HDFS-1725. Set storage directories only at FSImage construction (Ivan Kelly
               via todd)

    HDFS-1926. Remove references to StorageDirectory from JournalManager
               interface (Ivan Kelly via todd)

    HDFS-1893. Change edit logs and images to be named based on txid (todd)

    HDFS-1985. Clean up image transfer servlet (todd)

    HDFS-1984. Enable multiple secondary namenodes to run simultaneously (todd)

    HDFS-1987. Re-enable TestCheckpoint.testSecondaryImageDownload which was
               not running previously. (todd)

    HDFS-1993. TestCheckpoint needs to clean up between cases (todd)

    HDFS-1992. Remove vestiges of NNStorageListener. (todd)

    HDFS-1991. Some refactoring of Secondary NameNode to be able to share more
               code with the BackupNode or CheckpointNode. (todd)

    HDFS-1994. Fix race conditions when running two rapidly checkpointing
               Secondary NameNodes. (todd)

    HDFS-2001. Remove use of previous.checkpoint and lastcheckpoint.tmp
               directories (todd)

    HDFS-2015. Remove checkpointTxId from VERSION file. (todd)

    HDFS-2016. Add infrastructure to remove or archive old and unneeded storage
               files within the name directories. (todd)

    HDFS-2047. Improve TestNamespace and TestEditLog in HDFS-1073 branch.
               (todd)

    HDFS-2048. Add upgrade tests and fix upgrade from 0.22 with corrupt image.
               (todd)

    HDFS-2027. Image inspector should return finalized logs before unfinalized
               logs. (todd)

    HDFS-2074. Determine edit log validity by truly reading and validating
               transactions. (todd)

    HDFS-2085. Finalize in-progress edit logs at startup. (todd)

    HDFS-2026. SecondaryNameNode should properly handle the case where the
               NameNode is reformatted. (todd)

    HDFS-2077. Address checkpoint upload when one of the storage dirs is failed
               (todd)

    HDFS-2078. NameNode should not clear directory when restoring removed
               storage. (todd)

    HDFS-2088. Move edits log archiving logic into FSEditLog/JournalManager
               (todd)

    HDFS-2093. Handle case where an entirely empty log is left during NN crash
               (todd)

    HDFS-2102. Zero-pad edits filename to make them lexically sortable. (Ivan
               Kelly via todd)

    HDFS-2010. Fix NameNode to exit if all edit streams become inaccessible.
               (atm via todd)

    HDFS-2123. Checkpoint interval should be based on txn count, not size.
               (todd)

    HDFS-1979. Fix backupnode for new edits/image layout. (todd)

    HDFS-2101. Fix remaining unit tests for new storage filenames. (todd)

    HDFS-2133. Address remaining TODOs and pre-merge cleanup on HDFS-1073
               branch.  (todd)

    HDFS-1780. Reduce need to rewrite FSImage on startup. (todd)

    HDFS-2104. Add a flag to the 2NN to format its checkpoint dirs on startup.
               (todd)

    HDFS-2135. Fix regression of HDFS-1955 in HDFS-1073 branch. (todd)

    HDFS-2160. Fix CreateEditsLog test tool in HDFS-1073 branch. (todd)

    HDFS-2168. Reenable TestEditLog.testFailedOpen and fix exposed bug. (todd)

    HDFS-2169. Clean up TestCheckpoint and remove TODOs (todd)

    HDFS-2170. Address remaining TODOs in HDFS-1073 branch. (todd)

    HDFS-2172. Address findbugs and javadoc warnings in HDFS-1073 branch. 
               (todd)

    HDFS-2445. Ensure failed tests exit with proper error code. (Jonathan 
    Eagles via acmurthy)

Release 0.22.1 - Unreleased

  INCOMPATIBLE CHANGES

  NEW FEATURES

  IMPROVEMENTS

  OPTIMIZATIONS

    HDFS-2718. Optimize OP_ADD in edits loading. (shv)

    HDFS-2886. CreateEditLogs should generate a realistic edit log. (shv)

  BUG FIXES

   HDFS-2877. If locking of a storage dir fails, it will remove the other
   NN's lock file on exit. (todd)

Release 0.22.0 - 2011-11-29

  INCOMPATIBLE CHANGES

    HDFS-1825. Remove thriftfs contrib. (nigel via eli)

  NEW FEATURES

    HDFS-992. Re-factor block access token implementation to conform to the 
    generic Token interface in Common (Kan Zhang and Jitendra Pandey via jghoman)

    HDFS-599. Allow NameNode to have a seprate port for service requests from
    client requests. (Dmytro Molkov via hairong)

    HDFS-1004. Update NN to support Kerberized SSL from HADOOP-6584. 
    (jghoman and Kan Zhang via jghoman)

    HDFS-1005. Fsck security. (borya and Kan Zhang via jghoman)

    HDFS-1006. getImage/putImage http requests should be https for the case 
    of security enabled. (borya and jghoman via jghoman)

    HDFS-1033. In secure clusters, NN and SNN should verify that the remote 
    principal during image and edits transfer. (jghoman)

    HDFS-1023. Allow http server to start as regular principal if https 
    principal not defined. (jghoman)

    HDFS-1150. Verify datanodes' identities to clients in secure clusters.
    (jghoman)

    HDFS-1330. Make RPCs to DataNodes timeout. (hairong)
    Added additional unit tests per HADOOP-6889. (John George via mattf)

    HDFS-202.  HDFS support of listLocatedStatus introduced in HADOOP-6870.
    HDFS piggyback block locations to each file status when listing a
    directory.  (hairong)

    HDFS-1361. Add -fileStatus operation to NNThroughputBenchmark. (shv)

    HDFS-1435. Provide an option to store fsimage compressed. (hairong)

    HDFS-903.  Support fsimage validation through MD5 checksum. (hairong)

    HDFS-1457. Provide an option to throttle image transmission between
    pimary and secondary NameNodes. (Yifei Lu and hairong via hairong)

    HDFS-1164. TestHdfsProxy is failing. (Todd Lipcon via cos)

    HDFS-811. Add metrics, failure reporting and additional tests for HDFS-457.
    (eli)

    HDFS-895. Allow hflush/sync to occur in parallel with new writes
    to the file. (Todd Lipcon via hairong)

    HDFS-528. Add ability for safemode to wait for a minimum number of 
    live datanodes (Todd Lipcon via eli)

    HDFS-1753. Resource Leak in StreamFile. (Uma Maheswara Rao G via eli)

  IMPROVEMENTS

    HDFS-1304. Add a new unit test for HftpFileSystem.open(..).  (szetszwo)

    HDFS-1096. fix for prev. commit. (boryas)

    HDFS-1096. allow dfsadmin/mradmin refresh of superuser proxy group
     mappings (boryas)

    HDFS-1146. Javadoc for getDelegationTokenSecretManager in FSNamesystem (jnp via boryas)

    HDFS-1132. Refactor TestFileStatus (Eli Collins via cos)

    HDFS-1163. normalize property names for JT/NN kerberos principal 
    names in configuration (from HADOOP 6633) (boryas)

    HDFS-1003. authorization checks for inter-server protocol 
    (based on HADOOP-6600) (boryas)

    HDFS-1061. Memory footprint optimization for INodeFile object. 
    (Bharath Mundlapudi via jghoman)

    HDFS-1079. Throw exceptions as specified by the AbstractFileSystem
    in HDFS implemenation and protocols. (suresh)

    HDFS-1112. Edit log buffer should not grow unfoundedly. (hairong)

    HDFS-1119. Introduce a GSet interface to BlocksMap.  (szetszwo)

    HDFS-1184. Replace tabs in code with spaces. (Jeff Ames via jghoman)

    HDFS-1185. Remove duplicate now() functions in DataNode, FSNamesysetm.
    (Jeff Ames via jghoman)

    HDFS-1183. Remove some duplicate code in NamenodeJspHelper.java.
    (Jeff Ames via jghoman)
    
    HDFS-1190.  Remove unused getNamenode() method from DataNode.
    (Jeff Ames via jghoman)

    HDFS-1110. Reuses objects for commonly used file names in namenode to
    reduce the heap usage. (suresh)

    HDFS-752. Add interfaces classification to to HDFS source code. (suresh)

    HDFS-947. An Hftp read request is redirected to a datanode that has 
    the most replicas of the blocks in the file. (Dmytro Molkov via dhruba)

    HDFS-1272. Fixes to take care of the changes in HADOOP-6845.
    (Jitendra Pandey via ddas)

    HDFS-1298 - Add support in HDFS for new statistics added in FileSystem
    to track the file system operations. (suresh)

    HDFS-1201. The HDFS component for HADOOP-6632. 
    (Kan Zhang & Jitendra Pandey via ddas)
    
    HDFS-1307 Add start time, end time and total time taken for FSCK to 
    FSCK report (suresh)

    HDFS-1302. The HDFS side of the changes corresponding to HADOOP-6861.
    (Jitendra Pandey & Owen O'Malley via ddas)
    
    HDFS-1315. Add fsck event to audit log and remove other audit log events 
    corresponding to FSCK listStatus and open calls. (suresh)

    HDFS-1178. The NameNode servlets should not use RPC to connect to the 
    NameNode. (Kan Zhang via jghoman)

    HDFS-1130. Adds dfs.cluster.administrator ACL configuration that can
    be used to control who can view the default hdfs servlets. (ddas)

    HDFS-1297. Fix some comments. (Jeff Ames via jghoman)

    HDFS-330.  Datanode Web UIs should provide robots.txt.
    (Allen Wittenauer via jghoman)

    HDFS-881.  Refactor DataNode Packet header into DataTransferProtocol.
    (Todd Lipcon via jghoman)

    HDFS-1036. docs for fetchdt

    HDFS-1318. Add JMX interface for read access to namenode and datanode
    web UI information. (Tanping Wang via suresh).

    HDFS-1356.  Provide information as to whether or not security is 
    enabled on web interface for NameNode (boryas)

    HDFS-1205. FSDatasetAsyncDiskService should name its threads.
    (Todd Lipcon via eli)

    HDFS-1111. Introduce getCorruptFileBlocks() for fsck. (Sriram Rao via shv)

    HDFS-1395. Add @Override to FSDataset methods that implement
    FSDatasetInterface methods. (suresh)

    HDFS-1383. Improve the error messages when using hftp://.  (szetszwo)

    HDFS-1093. Change the FSNamesystem lock to a read/write lock. (dhruba)

    HDFS-1407. Change DataTransferProtocol methods to use Block instead 
    of individual elements of Block. (suresh)

    HDFS-1417. Add @Override to SimulatedFSDataset methods that implement
    FSDatasetInterface methods. (suresh)

    HDFS-1426. Remove unused method BlockInfo#listCount. (hairong)

    HDFS-1472. Allow programmatic access to fsck output.
    (Ramkumar Vadali via dhruba)

    HADOOP-7007. Update the hudson-test-patch ant target to work with the
    latest test-patch.sh script (gkesavan)

    HDFS-1462. Refactor edit log loading to a separate class from edit log writing.
    (Todd Lipcon via eli)

    HDFS-1485. Fix typo in BlockPlacementPolicy. (Jingguo Yao via shv)

    HDFS-1035. Generate Eclipse's .classpath file from Ivy config. (nigel)

    HDFS-1408. Herriot NN and DN clients should vend statistics. (cos)

    HDFS-1491  Update Hdfs to match the change of methods from protected to public
    in AbstractFileSystem (Hadoop-6903) (sanjay)

    HDFS-1160. Improve some FSDataset warnings and comments. (eli)

    HDFS-556. Provide info on failed volumes in the web ui. (eli)

    HDFS-697. Enable asserts for tests by default. (eli)

    HDFS-1187. Modify fetchdt to allow renewing and canceling token.
    (Owen O'Malley and Kan Zhang via jghoman)

    HDFS-1387. Update HDFS permissions guide for security. (Todd Lipcon via eli)

    HDFS-455. Make NN and DN handle in a intuitive way comma-separated 
    configuration strings. (Michele Catasta via eli)

    HDFS-1071. savenamespace should write the fsimage to all configured 
    fs.name.dir in parallel (Dmytro Molkov via jghoman)
 
    HDFS-1055. Improve thread naming for DataXceivers. 
    (Todd Lipcon and Ramkumar Vadali via eli).

    HDFS-718. Configuration parameter to prevent accidental formatting of 
    HDFS filesystem. (Andrew Ryan via jghoman)

    HDFS-1500. TestOfflineImageViewer failing on trunk. (Todd Lipcon
    via hairong)

    HDFS-1483. DFSClient.getBlockLocations should indicate if corresponding
    blocks are corrupt. (Patrick Kling via hairong)

    HDFS-259. Remove intentionally corrupt 0.13 directory layout creation.
    (Todd Lipcon via eli)

    HDFS-1513. Fix a number of warnings. (eli)

    HDFS-1473. Refactor storage management into separate classes than fsimage
    file reading/writing. (Todd Lipcon via eli)

    HDFS-1582. Remove auto-generated native build files. (rvs via eli)

    HDFS-1456. Provide builder for constructing instances of MiniDFSCluster.
    (jghoman)

    HDFS-1861. Rename dfs.datanode.max.xcievers and bump its default value.
    (eli)

    HDFS-1052. HDFS Federation - Merge of umbrella jira changes from
    HDFS-1052 branch into trunk.

    HDFS-1835. DataNode should not depend on SHA1PRNG secure random generator
    to generate a storage ID. (John Carrino via todd)

    HDFS-1947. DFSClient should use mapreduce.task.attempt.id. (eli)

    HDFS-1957. Add documentation for HFTP. (Ari Rabkin via todd)

    HDFS-1454. Update the documentation to reflect that clients don't write
    blocks to local disk before copying to HDFS. (Harsh J Chouraria via todd)

    HDFS-1980. Move build/webapps deeper in the build directory heirarchy
    to aid eclipse users. (todd)

    HDFS-1619. Remove AC_TYPE* from the libhdfs. (Roman Shaposhnik via eli)

    HDFS-1948  Forward port 'hdfs-1520 lightweight namenode operation to
    trigger lease recovery' (stack)

    HDFS-1954. Improved corrupt files warning on NameNode web UI.
    (Patrick Hunt via shv)

    HDFS-1409. BackupNode registration throwing  
    UnsupportedActionException("register") instead of "journal".
    (Ching-Shen Chen via shv)

    HDFS-2054  BlockSender.sendChunk() prints ERROR for connection closures
    encountered during transferToFully() (Kihwal Lee via stack)

  OPTIMIZATIONS

    HDFS-1140. Speedup INode.getPathComponents. (Dmytro Molkov via shv)

    HDFS-1081. Performance regression in 
    DistributedFileSystem::getFileBlockLocations in secure systems (jghoman)

    HDFS-1114. Implement LightWeightGSet for BlocksMap in order to reduce
    NameNode memory footprint.  (szetszwo)

    HDFS-1320. Add LOG.isDebugEnabled() guard for each LOG.debug(..).
    (Erik Steffl via szetszwo)

    HDFS-1368. Add a block counter to DatanodeDescriptor. (hairong)

    HDFS-1434. Refactor Datanode#startDataNode method into smaller methods.
    (suresh)

    HDFS-941. The DFS client should cache and reuse open sockets to datanodes
    while performing reads. (bc Wong and Todd Lipcon via todd)

  BUG FIXES

    HDFS-1039. Adding test for  JspHelper.getUGI(jnp via boryas)

    HDFS-1019. Incorrect default values for delegation tokens in 
    hdfs-default.xml (jnp via boryas)

    HDFS-1039.  Service should be set in the token in JspHelper.getUGI(jnp via boryas)

    HDFS-1038. FIX. A test missed in a previous commit for this JIRA. (boryas)

    HDFS-1038. In nn_browsedfscontent.jsp fetch delegation token only 
    if security is enabled. (jnp via boryas)

    HDFS-1044. Cannot submit mapreduce job from secure client to 
    unsecure sever (boryas)

    HDFS-1021. specify correct server principal for RefreshAuthorizationPolicyProtocol 
    and RefreshUserToGroupMappingsProtocol protocols in DFSAdmin (for HADOOP-6612) (boryas)

    HDFS-970. fsync fsimage to disk before closing fsimage file.
    (Todd Lipcon via dhruba)

    HDFS-1027. Update copyright year to 2010. (Ravi Phulari via jghoman)

    HDFS-1080. SecondaryNameNode image transfer should use the defined http 
    address rather than local ip address. (jghoman)

    HDFS-1198. Resolving cross-realm principals. (Jitendra Pandey via jghoman)

    HDFS-1118. Fix socketleak on DFSClient. (Zheng Shao via dhruba)

    HDFS-1192. refreshSuperUserGroupsConfiguration should use server side 
    configuration for the refresh (for HADOOP-6815) (boryas)

    HDFS-1036. in DelegationTokenFetch dfs.getURI returns no port (boryas)

    HDFS-1017. browsedfs jsp should call JspHelper.getUGI rather 
    than using createRemoteUser() (jnp via boryas)

    HDFS-1250. Namenode should reject block reports and block received
    requests from dead datanodes (suresh)

    HDFS-1145. When NameNode is shutdown it does not try to exit
    safemode anymore. (dhruba)

    HDFS-1202. DataBlockScanner throws NPE when updated before 
    initialized. (Todd Lipcon via dhruba)

    HDFS-882. Datanode logs the hostname and port its listening on.
    (Steve Loughran via dhruba)

    HDFS-1238. ant eclipse-files has drifted again, (jghoman)

    HDFS-1045. In secure clusters, re-login is necessary for https 
    clients before opening connections. (jghoman)

    HDFS-1289. Datanode secure mode is broken. (Kan Zhang via jghoman)

    HDFS-1007. HFTP needs to be updated to use delegation tokens (boryas)

    HDFS-1085. HFTP read may fail silently on the client side if there is an
    exception on the server side.  (szetszwo)

    HDFS-1308. job conf key for the services name of DelegationToken for HFTP
    url is constructed incorrectly in HFTPFileSystem (boryas)

    HDFS-1319. Fix location of re-login for secondary namenode from HDFS-999. 
    (jghoman)

    HDFS-1317. Remove the FILEPATH_PATTERN from hdfsproxy.AuthorizationFilter.
    (Rohini Palaniswamy via szetszwo)

    HDFS-912. sed in build.xml on Solaris fails. (Allen Wittenauer via jghoman)

    HDFS-1296. using delegation token over hftp for long running 
    clients (boryas)

    HDFS-1334. open in HftpFileSystem does not add delegation tokens to the url.
    (Jitendra Pandey via jghoman)

    HDFS-1301.  TestHDFSProxy need to use server side conf for ProxyUser 
    stuff. (boryas)

    HDFS-1340. When security is turned off, there is a potential XSS attack. 
    This patch fixes it by removing delegationtoken string from the URL, 
    before returning a response to the client. (Jitendra Pandey via ddas)

    HDFS-1347.  TestDelegationToken uses mortbay.log for logging (boryas)

    HDFS-1157. Modifications introduced by HDFS-1150 are breaking aspect's
    bindings (cos)

    HDFS-1349. Remove empty java files. (Eli Collins)

    HDFS-1340. A null delegation token is appended to the url if security
    is disabled when browsing filesystem. (boryas)
    
    HDFS-1352. Fix jsvc.location. (Eli Collins via jghoman)

    HDFS-1284. TestBlockToken fails.  (Kan Zhang via jghoman)

    HDFS-1355. ant veryclean (clean-cache) doesn't clean enough. 
    (Luke Lu via jghoman)

    HDFS-1353. Remove most of getBlockLocation optimization. (jghoman)

    HDFS-1369. Invalid javadoc reference in FSDatasetMBean.java (Eli Collins)

    HDFS-829. hdfsJniHelper.c: #include <error.h> is not portable. 
    (Allen Wittenauer via jghoman)

    HDFS-1310. The ClientDatanodeProtocol proxy should be stopped in
    DFSInputStream.readBlockLength(..).  (sam rash via szetszwo)

    HDFS-1357. HFTP traffic served by DataNode shouldn't use service port 
    on NameNode. (Kan Zhang via jghoman)

    HDFS-1419. HDFS Federation: Three test cases need minor modification after 
    the new block id change (Tanping Wang via suresh)

    HDFS-96. HDFS supports blocks larger than 2 GB.
    (Patrick Kling via dhruba)

    HDFS-1433. Fix test failures - TestPread and TestFileLimit. (suresh)

    HDFS-1364. Makes long running HFTP-based applications do relogins
    if necessary. (Jitendra Pandey via ddas)

    HDFS-1399. Distinct minicluster services (e.g. NN and JT) overwrite each
    other's service policies.  (Aaron T. Myers via tomwhite)

    HDFS-1440. Fix TestComputeInvalidateWork failure. (suresh)
 
    HDFS-1498. FSDirectory#unprotectedConcat calls setModificationTime 
    on a file. (eli)

    HDFS-1625. Ignore disk space values in TestDataNodeMXBean.  (szetszwo)

    HDFS-1850. DN should transmit absolute failed volume count rather than 
    increments to the NN. (eli)

    HDFS-671. Documentation change for updated configuration keys. 
    (tomwhite via eli)

    HDFS-1544. Ivy resolve force mode should be turned off by default.
    (Luke Lu via tomwhite)

    HDFS-1615. seek() on closed DFS input stream throws NullPointerException
    (Scott Carey via todd)

    HDFS-1897. Documentation refers to removed option dfs.network.script
    (Andrew Whang via todd)

    HDFS-1621. Fix references to hadoop-common-${version} in build.xml
    (Jolly Chen via todd)

    HDFS-1505. saveNamespace appears to succeed even if all directories fail
    to save. (Aaron T. Myers via todd)

    HDFS-1921. saveNamespace can cause NN to be unable to come up on restart
    (Matt Foley via todd)

    HDFS-1925. SafeModeInfo should use the correct constant instead of a
    hard-coded value for its default. (Joey Echeverria via todd)

    HDFS-1575. Viewing block from web UI is broken. (Aaron T. Myers via todd)
    
    HDFS-1932. Ensure that HDFS configuration deprecations are set up in every
    spot that HDFS configurations are loaded. (Jolly Chen via todd)

    HDFS-1952. FSEditLog.open() appears to succeed even if all EDITS
    directories fail. (Andrew Wang via todd)

    HDFS-1965. IPCs done using block token-based tickets can't reuse
    connections (todd)

    HDFS-1978. All but first option in LIBHDFS_OPTS is ignored. (eli)

    HDFS-1964. Fix incorrect HTML unescaping in DatanodeJspHelper
    (Aaron T. Myers via todd)

    HDFS-1997. Image transfer process misreports client side exceptions.
    (todd via eli)

    HDFS-2000. Missing deprecation for io.bytes.per.checksum.
    (Aaron T. Myers vie eli)

    HDFS-977. DataNode.createInterDataNodeProtocolProxy() guards a log
    at the wrong level. (Harsh J Chouraria via todd)

    HDFS-1969. Running rollback on new-version namenode destroys the
    namespace. (todd)

    HDFS-2039. TestNameNodeMetrics uses a bad test root path, preventing it
    from running inside Eclipse. (todd)

    HDFS-988. saveNamespace race can corrupt the edits log. (eli)

    HDFS-2071. Use of isConnected() in DataXceiver is invalid. (Kihwal Lee
    via todd)

    HDFS-1981. NameNode does not saveNamespace() when editsNew is empty.
    (Uma Maheswara Rao G via shv)

    HDFS-2232. Generalize regular expressions in TestHDFSCLI.
    (Plamen Jeliazkov via shv)

    HDFS-2290. Block with corrupt replica is not getting replicated.
    (Benoy Antony via shv)

    HDFS-2452. OutOfMemoryError in DataXceiverServer takes down the DataNode
    (Uma Maheswara Rao via cos)

    HDFS-2002. Incorrect computation of needed blocks in getTurnOffTip().
    (Plamen Jeliazkov via shv)

    HDFS-2514. Link resolution bug for intermediate symlinks with
    relative targets. (eli)

    HDFS-1466. TestFcHdfsSymlink relies on /tmp/test not existing. (eli)

    HDFS-874. TestHDFSFileContextMainOperations fails on weirdly 
    configured DNS hosts. (Todd Lipcon via eli)

    HDFS-1507. TestAbandonBlock should abandon a block. (eli)

    HDFS-1487. FSDirectory.removeBlock() should update diskspace count 
    of the block owner node (Zhong Wang via eli).

    HDFS-1467. Append pipeline never succeeds with more than one replica.
    (Todd Lipcon via eli)

    HDFS-1167. New property for local conf directory in system-test-hdfs.xml
    file. (Vinay Thota via cos)

    HDFS-1503. TestSaveNamespace fails. (Todd Lipcon via cos)

    HDFS-1524. Image loader should make sure to read every byte in image file.
    (hairong)

    HDFS-1523. TestLargeBlock is failing on trunk. (cos)

    HDFS-1502. TestBlockRecovery triggers NPE in assert. (hairong via cos)

    HDFS-1532. Exclude Findbugs warning in FSImageFormat$Saver. (Todd Lipcon
    via cos)

    HDFS-1527. SocketOutputStream.transferToFully fails for blocks >= 2GB on
    32 bit JVM. (Patrick Kling via cos)

    HDFS-1531. Clean up stack traces due to duplicate MXBean registration.
    (Todd Lipcon via cos)

    HDFS-613. TestBalancer and TestBlockTokenWithDFS fail Balancer assert.
    (Todd Lipcon via cos)

    HDFS-1511. 98 Release Audit warnings on trunk and branch-0.22.
    (jghoman)

    HDFS-1560. dfs.data.dir permissions should default to 700. 
    (Todd Lipcon via eli)

    HDFS-1550. NPE when listing a file with no location. (hairong)

    HDFS-1542. Add test for HADOOP-7082, a deadlock writing Configuration to
    HDFS. (todd)

    HDFS-1504. FSImageSaver should catch all exceptions, not just IOE. (todd)

    HDFS-884. DataNode throws IOException if all data directories are 
    unavailable. (Steve Loughran and shv)

    HDFS-1591. HDFS part of HADOOP-6642. (Chris Douglas, Po Cheung via shv)

    HDFS-900. Corrupt replicas are not processed correctly in block report (shv)

    HDFS-1529. Incorrect handling of interrupts in waitForAckedSeqno can cause
    deadlock (todd)

    HDFS-1597. Batched edit log syncs can reset synctxid and throw assertions
    (todd)

    HDFS-1602. Fix HADOOP-4885 for it is doesn't work as expected. (boryas)

    HDFS-1618. configure files that are generated as part of the released
    tarball need to have executable bit set (Roman Shaposhnik via cos)

    HDFS-981. test-contrib fails due to test-cactus failure (cos)

    HDFS-1001. DataXceiver and BlockReader disagree on when to send/recv
    CHECKSUM_OK. (bc Wong via eli)

    HDFS-1781. Fix the path for jsvc in bin/hdfs.  (John George via szetszwo)

    HDFS-1782. Fix an NPE in FSNamesystem.startFileInternal(..).
    (John George via szetszwo)

    HDFS-1821. Fix username resolution in NameNode.createSymlink(..) and
    FSDirectory.addSymlink(..).  (John George via szetszwo)

    HDFS-1806. TestBlockReport.blockReport_08() and _09() are timing-dependent
    and likely to fail on fast servers. (Matt Foley via eli)

    HDFS-1845. Symlink comes up as directory after namenode restart.
    (John George via eli)

    HDFS-1666. Disable failing hdfsproxy test TestAuthorizationFilter (todd)

    HDFS-1823. start-dfs.sh script fails if HADOOP_HOME is not set.
    (tomwhite via eli)

Release 0.21.1 - Unreleased

    HDFS-1411. Correct backup node startup command in hdfs user guide.
    (Ching-Shen Chen via shv)

  BUG FIXES

    HDFS-1363. Eliminate second synchronized sections in appendFile(). (shv)

    HDFS-1413. Fix broken links to HDFS Wiki. (shv)

    HDFS-1420. Clover build doesn't generate per-test coverage (cos)

    HDFS-1444. Test related code of build.xml is error-prone and needs to be
    re-aligned. (cos)

    HDFS-1343. Instrumented build should be concentrated in one build area (cos)

    HDFS-1452. ant compile-contrib is broken (cos)

    HDFS-1474. ant binary-system is broken (cos)

    HDFS-1292. Allow artifacts to be published to the staging Apache Nexus
    Maven Repository.  (Giridharan Kesavan via tomwhite)

    HDFS-1552. Remove java5 dependencies from build. (cos) 

    HDFS-1189. Quota counts missed between clear quota and set quota.
    (John George via szetszwo)

    HDFS-1665. Balancer misuses dfs.heartbeat.interval as milliseconds.
    (szetszwo)

    HDFS-1728. SecondaryNameNode.checkpointSize is in bytes but not in MB.
    (szetszwo)

    HDFS-1206. TestFiHFlush fails intermittently. (cos)

    HDFS-1548. Fault-injection tests are executed multiple times if invoked
    with run-test-hdfs-fault-inject target (cos)

    HDFS-1552. Remove java5 dependencies from build. (cos) 

    HDFS-996. JUnit tests should never depend on anything in conf (cos)

    HDFS-1612. Update HDFS design documentation for append, quota, symlink,
    block placement and checkpoint/backup node features.  (Joe Crobak
    via szetszwo)


    HDFS-1596. Replace fs.checkpoint.* with dfs.namenode.checkpoint.*
    in documentations.  (Harsh J Chouraria via szetszwo)

    HDFS-1786. Some cli test cases expect a "null" message
    (Uma Maheswara Rao G via todd)

    HDFS-1855. TestDatanodeBlockScanner.testBlockCorruptionRecoveryPolicy()
    part 2 fails in two different ways. (Matt Foley via eli)

Release 0.21.0 - 2010-08-13

  INCOMPATIBLE CHANGES

    HDFS-538. Per the contract elucidated in HADOOP-6201, throw
    FileNotFoundException from FileSystem::listStatus rather than returning
    null. (Jakob Homan via cdouglas)

    HDFS-602. DistributedFileSystem mkdirs throws FileAlreadyExistsException
    instead of FileNotFoundException. (Boris Shkolnik via suresh)

    HDFS-544. Add a "rbw" subdir to DataNode data directory. (hairong)

    HDFS-576. Block report includes under-construction replicas. (shv)

    HDFS-636. SafeMode counts complete blocks only. (shv)

    HDFS-644. Lease recovery, concurrency support. (shv)

    HDFS-570. Get last block length from a data-node when opening a file
    being written to. (Tsz Wo (Nicholas), SZE via shv)

    HDFS-657. Remove unused legacy data-node protocol methods. (shv)

    HDFS-658. Block recovery for primary data-node. (shv)

    HDFS-660. Remove deprecated methods from InterDatanodeProtocol. (shv)

    HDFS-512. Block.equals() and compareTo() compare blocks based
    only on block Ids, ignoring generation stamps. (shv)

    HDFS-873. Configuration specifies data-node storage directories as URIs.
    (shv)

    HDFS-905. Use the new UserGroupInformation from HDFS-6299. 
    (jghoman via omalley)

    HDFS-984. Persistent delegation tokens. (Jitendra Pandey via shv)

    HDFS-1016. HDFS side change for HADOOP-6569. This jira changes the
    error message on the screen when cat a directory or a 
    non-existent file. (hairong)

  NEW FEATURES

    HDFS-1134. Large-scale Automated Framework. (cos)

    HDFS-436. Introduce AspectJ framework for HDFS code and tests.
    (Konstantin Boudnik via szetszwo)

    HDFS-447. Add LDAP lookup to hdfsproxy. (Zhiyong Zhang via cdouglas)

    HDFS-459. Introduce Job History Log Analyzer. (shv)

    HDFS-461. Tool to analyze file size distribution in HDFS. (shv)

    HDFS-492. Add two JSON JSP pages to the Namenode for providing corrupt
    blocks/replicas information.  (Bill Zeller via szetszwo)

    HDFS-578. Add support for new FileSystem method for clients to get server
    defaults. (Kan Zhang via suresh)

    HDFS-595. umask settings in configuration may now use octal or symbolic 
    instead of decimal. (Jakob Homan via suresh)

    HADOOP-6234. Updated hadoop-core and test jars to propagate new option 
    dfs.umaskmode in configuration. (Jakob Homan via suresh)

    HDFS-235. Add support for byte ranges in HftpFileSystem to serve
    range of bytes from a file. (Bill Zeller via suresh)

    HDFS-385. Add support for an experimental API that allows a module external
    to HDFS to specify how HDFS blocks should be placed. (dhruba)

    HADOOP-4952. Update hadoop-core and test jars to propagate new FileContext
    file system application interface. (Sanjay Radia via suresh).

    HDFS-567. Add block forensics contrib tool to print history of corrupt and
    missing blocks from the HDFS logs.
    (Bill Zeller, Jitendra Nath Pandey via suresh).

    HDFS-610. Support o.a.h.fs.FileContext.  (Sanjay Radia via szetszwo)

    HDFS-536. Support hflush at DFSClient. (hairong)

    HDFS-517. Introduce BlockInfoUnderConstruction to reflect block replica
    states while writing. (shv)

    HDFS-565. Introduce block committing logic during new block allocation
    and file close. (shv)

    HDFS-537. DataNode exposes a replica's meta info to BlockReceiver for the
    support of dfs writes/hflush. It also updates a replica's bytes received,
    bytes on disk, and bytes acked after receiving a packet. (hairong)

    HDFS-585. Datanode should serve up to visible length of a replica for read
    requests.  (szetszwo)

    HDFS-604. Block report processing for append. (shv)

    HDFS-619. Support replica recovery initialization in datanode for the new
    append design.  (szetszwo)

    HDFS-592. Allow clients to fetch a new generation stamp from NameNode for
    pipeline recovery. (hairong)

    HDFS-624. Support a new algorithm for pipeline recovery and pipeline setup
    for append. (hairong)

    HDFS-627. Support replica update in data-node.
    (Tsz Wo (Nicholas), SZE and Hairong Kuang via shv)

    HDFS-642. Support pipeline close and close error recovery. (hairong)

    HDFS-631. Rename configuration keys towards API standardization and
    backward compatibility. (Jitendra Nath Pandey via suresh)

    HDFS-669. Add unit tests framework (Mockito) (cos, Eli Collins)

    HDFS-731. Support new Syncable interface in HDFS. (hairong)

    HDFS-702. Add HDFS implementation of AbstractFileSystem. 
    (Sanjay Radio via suresh)

    HDFS-758. Add decommissioning status page to Namenode Web UI.
    (Jitendra Nath Pandey via suresh)

    HDFS-814. Add an api to get the visible length of a DFSDataInputStream.
    (szetszwo)

    HDFS-654. Add support new atomic rename functionality in HDFS for 
    supporting rename in FileContext. (suresh)

    HDFS-222. Support for concatenating of files into a single file
    without copying. (Boris Shkolnik via hairong)

    HDFS-933. Adds Delegation token based authentication in the NameNode.
    (Kan Zhang via ddas)

    HDFS-935. Adds a real user component in Delegation token.
    (Jitendra Nath Pandey via ddas)

    HDFS-245. Adds a symlink implementation to HDFS. This complements the new 
    symlink feature added in HADOOP-6421 (Eli Collins via Sanjay Radia)

    HDFS-1009. Support Kerberos authorization in HDFSProxy.  (Srikanth
    Sundarrajan via szetszwo)

    HDFS-1091. Implement listStatus that returns an iterator of FileStatus.
    (hairong)

  IMPROVEMENTS

    HDFS-381. Remove blocks from DataNode maps when corresponding file
    is deleted. (Suresh Srinivas via rangadi)

    HDFS-377. Separate codes which implement DataTransferProtocol.
    (szetszwo)

    HDFS-396. NameNode image and edits directories are specified as URIs.
    (Luca Telloli via rangadi)

    HDFS-444. Allow to change probability levels dynamically in the fault
    injection framework.  (Konstantin Boudnik via szetszwo)

    HDFS-352. Documentation for saveNamespace command. (Ravi Phulari via shv)

    HADOOP-6106. Updated hadoop-core and test jars from hudson trunk 
    build #12. (Giridharan Kesavan)

    HDFS-204. Add a new metrics FilesInGetListingOps to the Namenode.
    (Jitendra Nath Pandey via szetszwo)

    HDFS-278. HDFS Outputstream close does not hang forever. (dhruba)

    HDFS-443. Add a new metrics numExpiredHeartbeats to the Namenode.
    (Jitendra Nath Pandey via szetszwo)

    HDFS-475. Add new ant targets for fault injection jars and tests.
    (Konstantin Boudnik via szetszwo)

    HDFS-458. Create a new ant target, run-commit-test.  (Jakob Homan
    via szetszwo)

    HDFS-493. Change build.xml so that the fault-injected tests are executed
    only by the run-test-*-fault-inject targets.  (Konstantin Boudnik via
    szetszwo)

    HDFS-446. Improvements to Offline Image Viewer. (Jakob Homan via shv)

    HADOOP-6160. Fix releaseaudit target to run on specific directories.
    (gkesavan)

    HDFS-501. Use enum to define the constants in DataTransferProtocol.
    (szetszwo)

    HDFS-508. Factor out BlockInfo from BlocksMap. (shv)

    HDFS-510. Rename DatanodeBlockInfo to be ReplicaInfo.
    (Jakob Homan & Hairong Kuang via shv)

    HDFS-500. Deprecate NameNode methods deprecated in NameNodeProtocol.
    (Jakob Homan via shv)

    HDFS-514. Change DFSClient.namenode from public to private.  (Bill Zeller
    via szetszwo)

    HDFS-496. Use PureJavaCrc32 in HDFS.  (Todd Lipcon via szetszwo)

    HDFS-511. Remove redundant block searches in BlockManager. (shv)

    HDFS-504. Update the modification time of a file when the file 
    is closed. (Chun Zhang via dhruba)

    HDFS-498. Add development guide and documentation for the fault injection
    framework.  (Konstantin Boudnik via szetszwo)

    HDFS-524. Further DataTransferProtocol code refactoring.  (szetszwo)

    HDFS-529. Use BlockInfo instead of Block to avoid redundant block searches
    in BlockManager. (shv)

    HDFS-530. Refactor TestFileAppend* to remove code duplication.
    (Konstantin Boudnik via szetszwo)

    HDFS-451. Add fault injection tests for DataTransferProtocol.  (szetszwo)

    HDFS-409. Add more access token tests.  (Kan Zhang via szetszwo)

    HDFS-546. DatanodeDescriptor iterates blocks as BlockInfo. (shv)

    HDFS-457. Do not shutdown datanode if some, but not all, volumes fail.
    (Boris Shkolnik via szetszwo)

    HDFS-548. TestFsck takes nearly 10 minutes to run. (hairong)

    HDFS-539. Refactor fault injeciton pipeline test util for future reuse.
    (Konstantin Boudnik via szetszwo)

    HDFS-552. Change TestFiDataTransferProtocol to junit 4 and add a few new
    tests.  (szetszwo)

    HDFS-563. Simplify the codes in FSNamesystem.getBlockLocations(..).
    (szetszwo)

    HDFS-581. Introduce an iterator over blocks in the block report array.(shv)

    HDFS-549. Add a new target, run-with-fault-inject-testcaseonly, which
    allows an execution of non-FI tests in FI-enable environment.  (Konstantin
    Boudnik via szetszwo)

    HDFS-173. Namenode will not block until a large directory deletion 
    completes. It allows other operations when the deletion is in progress. 
    (suresh)

    HDFS-551. Create new functional test for a block report. (Konstantin
    Boudnik via hairong)

    HDFS-288. Redundant computation in hashCode() implementation.
    (szetszwo via tomwhite)

    HDFS-412. Hadoop JMX usage makes Nagios monitoring impossible.
    (Brian Bockelman via tomwhite)

    HDFS-472. Update hdfsproxy documentation. Adds a setup guide and design
    document. (Zhiyong Zhang via cdouglas)

    HDFS-617. Support non-recursive create().  (Kan Zhang via szetszwo)

    HDFS-618. Support non-recursive mkdir().  (Kan Zhang via szetszwo)

    HDFS-574. Split the documentation between the subprojects.
    (Corinne Chandel via omalley)

    HDFS-598. Eclipse launch task for HDFS. (Eli Collins via tomwhite)

    HDFS-641. Move all of the components that depend on map/reduce to 
    map/reduce. (omalley)

    HDFS-509. Redesign DataNode volumeMap to include all types of Replicas.
    (hairong)

    HDFS-562. Add a test for NameNode.getBlockLocations(..) to check read from
    un-closed file.  (szetszwo)

    HDFS-543. Break FSDatasetInterface#writToBlock() into writeToRemporary,
    writeToRBW, ad append. (hairong)

    HDFS-603. Add a new interface, Replica, which is going to replace the use
    of Block in datanode.  (szetszwo)

    HDFS-589. Change block write protocol to support pipeline recovery.
    (hairong)

    HDFS-652. Replace BlockInfo.isUnderConstruction() with isComplete() (shv)

    HDFS-648. Change some methods in AppendTestUtil to public.  (Konstantin
    Boudnik via szetszwo)

    HDFS-662. Unnecessary info message from DFSClient. (hairong)

    HDFS-518. Create new tests for Append's hflush. (Konstantin Boudnik
    via szetszwo)

    HDFS-688. Add configuration resources to DFSAdmin. (shv)

    HDFS-29. Validate the consistency of the lengths of replica and its file 
    in replica recovery.  (szetszwo)

    HDFS-680. Add new access method to a copy of a block's replica. (shv)

    HDFS-704. Unify build property names to facilitate cross-projects
    modifications (cos)

    HDFS-705. Create an adapter to access some of package-private methods of
    DataNode from tests (cos)

    HDFS-710. Add actions with constraints to the pipeline fault injection
    tests and change SleepAction to support uniform random sleeping over an
    interval.  (szetszwo)

    HDFS-713. Need to properly check the type of the test class from an aspect
    (cos)

    HDFS-716. Define a pointcut for pipeline close and add a few fault
    injection tests to simulate out of memory problem.  (szetszwo)

    HDFS-719. Add 6 fault injection tests for pipeline close to simulate slow
    datanodes and disk errors.  (szetszwo)

    HDFS-616. Create functional tests for new design of the block report. (cos)
    
    HDFS-584. Fail the fault-inject build if any advices are mis-bound. (cos)

    HDFS-730. Add 4 fault injection tests to simulate non-responsive datanode
    and out-of-memory problem for pipeline close ack.  (szetszwo)

    HDFS-728. Create a comprehensive functional test for append. (hairong)

    HDFS-736. commitBlockSynchronization() updates block GS and length 
    in-place. (shv)

    HADOOP-5107. Use Maven ant tasks to publish the subproject jars.
    (Giridharan Kesavan via omalley)

    HDFS-521. Create new tests for pipeline (cos)

    HDFS-764. Places the Block Access token implementation in hdfs project.
    (Kan Zhang via ddas)

    HDFS-787. Upgrade some libraries to be consistent with common and 
    mapreduce. (omalley)

    HDFS-519. Create new tests for lease recovery (cos)

    HDFS-804. New unit tests for concurrent lease recovery (cos)

    HDFS-813. Enable the append test in TestReadWhileWriting.  (szetszwo)

    HDFS-145. Cleanup inconsistent block length handling code in
    FSNameSystem#addStoredBlock. (hairong)

    HDFS-127. Reset failure count in DFSClient for each block acquiring
    operation.  (Igor Bolotin via szetszwo)

    HDFS-520. Create new tests for block recovery. (hairong)

    HDFS-1067. Create block recovery tests that handle errors. (hairong)

    HDFS-1107. Turn on append by default. (shv)

    HDFS-968. Use StringBuilder instead of StringBuffer for better
    performance. (Kay Kay via suresh)
    
    HDFS-703. Replace current fault injection implementation with one
    from (cos)

    HDFS-754. Reduce ivy console output to observable level (cos)

    HDFS-832. HDFS side of HADOOP-6222. (cos)

    HDFS-840. Change tests to use FileContext test helper introduced in
    HADOOP-6394. (Jitendra Nath Pandey via suresh)

    HDFS-685. Use the user-to-groups mapping service in the NameNode. 
    (boryas, acmurthy)

    HDFS-755. Read multiple checksum chunks at once in DFSInputStream.
    (Todd Lipcon via tomwhite)

    HDFS-786. Implement getContentSummary in HftpFileSystem.
    (Tsz Wo (Nicholas), SZE via cdouglas)

    HDFS-587. Add support for specifying queue name in mapreduce tests.
    (Erik Steffl via suresh)

    HDFS-902 Move contrib/raid to MapReduce. (Eli Collins via omalley)

    HDFS-800. The last block of a file under construction may change to the
    COMPLETE state in response to getAdditionalBlock or completeFileInternal.
    (hairong)

    HDFS-899. Delegation Token Implementation
     and corresponding changes in Namenode and DFS Api to issue, 
    renew and cancel delegation tokens. (jnp via boryas)

    HDFS-844. Log the filename when file locking fails. (tomwhite)

    HDFS-914. Refactor DFSOutputStream and DFSInputStream out of DFSClient.
    (Todd Lipcon via tomwhite)

    HDFS-949. Move DelegationToken into Common so that it can be used by
    MapReduce. (omalley)

    HDFS-930. Better error message for DATA_TRANSFER_VERSION mismatched.
    (Kay Kay via szetszwo)

    HDFS-986. Delegation token renewing and cancelling should provide
    meaningful exceptions when there are failures instead of returning 
    false. (omalley)

    HADOOP-6579. Upgrade the commons-codec library to 1.4. (omalley)

    HDFS-991. Allow authentication to the web ui via a delegation token. 
    (omalley)

    HDFS-994. Allow fetching of delegation token from NameNode for hftp.
    (Jakob Homan via acmurthy) 

    HDFS-998. Quote blocks streamed through jsps. (cdouglas)

    HDFS-729. NameNode API to list files that have missing blocks.
    (Rodrigo Schmidt via dhruba)

    HDFS-850. The WebUI display more details about namenode memory usage.
    (Dmytro Molkov via dhruba)

    HDFS-826. The DFSOutputStream has a API that returns the number of
    active datanode(s) in the current pipeline. (dhruba)

    HDFS-985. HDFS should issue multiple RPCs for listing a large
    directory. (hairong)

    HDFS-1043. NNThroughputBenchmark modifications to support benchmarking of
    server-side user group resolution. (shv)

    HDFS-892. Optionally use Avro reflection for Namenode RPC.  This
    is not a complete implementation yet, but rather a starting point.
    (cutting)
    
    HDFS-854. Datanode should scan devices in parallel to generate
    block report. (Dmytro Molkov via jhoman)

    HDFS-1032. fsck has an option to list corrupt files.
    (Andre Oriai via dhruba)

    HDFS-1024. SecondaryNameNode verifies size of fsimage and edits file.
    (Dmytro Molkov via dhruba)
    
    HDFS-1011. hdfsproxy: Improve log messages by restoring the previous
    thread name.  (Srikanth Sundarrajan via szetszwo)

    HDFS-997. Allow datanode storage directory permissions to be configurable.
    (Luke Lu via cdouglas)

    HDFS-1012. hdfsproxy: Support for fully qualified HDFS path in addition to
    simple unqualified path.  (Srikanth Sundarrajan via szetszwo)

    HDFS-933. Namenode should issue a delegation token only for kerberos 
    authenticated clients.(jnp via boryas)

    HDFS-1087. Modify audit log to use a StringBuilder rather than a Formatter.
    (cdouglas)

    HDFS-1083. Update TestHDFSCLI not to expect exception class name
    in error messages. (suresh)

    HDFS-1099. Add test for umask backward compatibility. (suresh)

    HDFS-1092. Use logging rather than System.err in MiniDFSCluster.
    (Kay Kay via jghoman)

    HDFS-1047. Install/deploy source jars to Maven repo. 
    (Patrick Angeles via jghoman)

    HDFS-666. Unit test for FsShell -text. (cdouglas via jghoman)

    HDFS-1054. Remove unnecessary sleep after failure in nextBlockOutputStream.
    (Todd Lipcon via jghoman)

    HDFS-921. Convert TestDFSClientRetries::testNotYetReplicatedErrors
    to Mockito. (jghoman)

    HDFS-1100. Override unwrapException in TestFcHdfsSymlink to test 
    symlink API conformance. (Eli Collins via suresh).

    HDFS-1089. Remove uses of FileContext#isFile, isDirectory, and exists.
    (Eli Collins via hairong)

    HDFS-1028. Efficient splitting of path components reduces the time
    to load in fsimage by 20%. (Dmytro Molkov via dhruba)

    HDFS-1109. HFTP supports filenames that contains the character "+".
    (Dmytro Molkov via dhruba)

    HDFS-853. The HDFS webUI displays the balanced-ness of the cluster.
    (Dmytro Molkov via dhruba)

    HDFS-1126. Change HDFS to depend on Hadoop 'common' artifacts instead
    of 'core'. (tomwhite)

    HDFS-995.  Replace usage of FileStatus#isDir().  (Eli Collins via
    tomwhite)

    HDFS-1161.  Make DN minimum valid volumes configurable.
    (Eli Collins via tomwhite)

    HDFS-1181. Move configuration and script files post split. (tomwhite)

    HDFS-1170.  Add more assertions to TestLargeDirectoryDelete.
    (Steve Loughran via tomwhite)

    HDFS-1199. Extract a subset of tests for smoke (DOA) validation. (cos)

    HDFS-1174. New properties for suspend and resume process. (Vinay Thota via
    cos)

    HDFS-1277. [Herriot] New property for multi user list. (Vinay Thota via
    cos)

    HDFS-806. Add new unit tests to the 10-mins 'run-commit-test' target (cos)

  OPTIMIZATIONS

    HDFS-946. NameNode should not return full path name when lisitng a
    diretory or getting the status of a file. (hairong)

  BUG FIXES

    HDFS-76. Better error message to users when commands fail because of 
    lack of quota. Allow quota to be set even if the limit is lower than
    current consumption. (Boris Shkolnik via rangadi)

    HADOOP-4687. HDFS is split from Hadoop Core. It is a subproject under 
    Hadoop (Owen O'Malley)

    HADOOP-6096. Fix Eclipse project and classpath files following project
    split. (tomwhite)

    HDFS-195. Handle expired tokens when write pipeline is reestablished.
    (Kan Zhang via rangadi)

    HDFS-181. Validate src path in FSNamesystem.getFileInfo(..).  (Todd
    Lipcon via szetszwo)

    HDFS-441. Remove TestFTPFileSystem.  (szetszwo)

    HDFS-440. Fix javadoc broken links in DFSClient.  (szetszwo)

    HDFS-480. Fix a typo in the jar name in build.xml.  
    (Konstantin Shvachko via gkesavan)

    HDFS-438. Check for NULL before invoking GenericArgumentParser in
    DataNode. (Raghu Angadi)

    HDFS-415. BlockReceiver hangs in case of certain runtime exceptions.
    (Konstantin Boudnik via rangadi)

    HDFS-462. loadFSImage should close edits file. (Jakob Homan via shv)

    HDFS-489. Update TestHDFSCLI for the -skipTrash option in rm. (Jakob Homan
    via szetszwo)

    HDFS-445. pread() does not pick up changes to block locations. 
    (Kan Zhang via rangadi) 

    HDFS-463. CreateEditLog utility broken after HDFS-396 (URI for
    FSImage). (Suresh Srinivas via rangadi)

    HDFS-484. Fix bin-package and package target to package jar files.
    (gkesavan)

    HDFS-490. Eliminate the deprecated warnings introduced by H-5438.
    (He Yongqiang via szetszwo)

    HDFS-119. Fix a bug in logSync(), which causes NameNode block forever.
    (Suresh Srinivas via shv)

    HDFS-534. Include avro in ivy.  (szetszwo)

    HDFS-532. Allow applications to know that a read request failed 
    because block is missing. (dhruba)

    HDFS-561. Fix write pipeline READ_TIMEOUT in DataTransferProtocol.
    (Kan Zhang via szetszwo)

    HDFS-553. BlockSender reports wrong failed position in ChecksumException.
    (hairong)

    HDFS-568. Set mapred.job.tracker.retire.jobs to false in
    src/test/mapred-site.xml for mapreduce tests to run.  (Amareshwari
    Sriramadasu via szetszwo)
 
    HDFS-15. All replicas end up on 1 rack. (Jitendra Nath Pandey via hairong)
 
    HDFS-586. TestBlocksWithNotEnoughRacks sometimes fails.
    (Jitendra Nath Pandey via hairong)

    HADOOP-6243. Fixed a NullPointerException in handling deprecated keys.
    (Sreekanth Ramakrishnan via yhemanth)

    HDFS-605. Do not run fault injection tests in the run-test-hdfs-with-mr
    target.  (Konstantin Boudnik via szetszwo)

    HDFS-606. Fix ConcurrentModificationException in invalidateCorruptReplicas()
    (shv)

    HDFS-601. TestBlockReport obtains data directories directly from
    MiniHDFSCluster. (Konstantin Boudnik via shv)

    HDFS-614. TestDatanodeBlockScanner obtains data directories directly from
    MiniHDFSCluster. (shv)

    HDFS-612. Remove the use of org.mortbay.log.Log in FSDataset.  (szetszwo)

    HDFS-622. checkMinReplication should count live nodes only. (shv)

    HDFS-629. Remove ReplicationTargetChooser.java along with fixing 
    import warnings generated by Eclipse. (dhruba)

    HDFS-637. DataNode sends a Success ack when block write fails. (hairong)

    HDFS-640. Fixed TestHDFSFileContextMainOperations.java build failure. (suresh)

    HDFS-547. TestHDFSFileSystemContract#testOutputStreamClosedTwice
    sometimes fails with CloseByInterruptException. (hairong)

    HDFS-588. Fix TestFiDataTransferProtocol and TestAppend2 failures. (shv)

    HDFS-550. DataNode restarts may introduce corrupt/duplicated/lost replicas
    when handling detached replicas. (hairong)

    HDFS-659. If the the last block is not complete, update its length with
    one of its replica's length stored in datanode.  (szetszwo)

    HDFS-649. Check null pointers for DataTransferTest.  (Konstantin Boudnik
    via szetszwo)

    HDFS-661. DataNode upgrade fails on non-existant current directory.
    (hairong)

    HDFS-597. Mofication introduced by HDFS-537 breakes an advice binding in
    FSDatasetAspects.  (Konstantin Boudnik via szetszwo)

    HDFS-665. TestFileAppend2 sometimes hangs. (hairong)

    HDFS-676. Fix NPE in FSDataset.updateReplicaUnderRecovery() (shv)

    HDFS-673. BlockReceiver#PacketResponder should not remove a packet from
    the ack queue before its ack is sent. (hairong)

    HDFS-682. Fix bugs in TestBlockUnderConstruction.  (szetszwo)

    HDFS-668. TestFileAppend3#TC7 sometimes hangs. (hairong)

    HDFS-679. Appending to a partial chunk incorrectly assumes the
    first packet fills up the partial chunk. (hairong)

    HDFS-722. Fix callCreateBlockWriteStream pointcut in FSDatasetAspects.
    (szetszwo)

    HDFS-690. TestAppend2#testComplexAppend failed on "Too many open files".
    (hairong)

    HDFS-725. Support the build error fix for HADOOP-6327.  (Sanjay Radia via
    szetszwo)

    HDFS-625. Fix NullPointerException thrown from ListPathServlet. (suresh)

    HDFS-735. TestReadWhileWriting has wrong line termination symbols (cos)

    HDFS-691. Fix an overflow error in DFSClient.DFSInputStream.available().
    (szetszwo)

    HDFS-733. TestBlockReport fails intermittently. (cos)

    HDFS-774. Intermittent race condition in TestFiPipelines (cos)

    HDFS-741. TestHFlush test doesn't seek() past previously written part of
    the file (cos, szetszwo)

    HDFS-706. Intermittent failures in TestFiHFlush (cos)
 
    HDFS-646. Fix test-patch failure by adding test-contrib ant target.
    (gkesavan)

    HDFS-791. Build is broken after HDFS-787 patch has been applied (cos)

    HDFS-792. TestHDFSCLI is failing. (Todd Lipcon via cos)

    HDFS-781. Namenode metrics PendingDeletionBlocks is not decremented.
    (Suresh)

    HDFS-192. Fix TestBackupNode failures. (shv)

    HDFS-797. TestHDFSCLI much slower after HDFS-265 merge. (Todd Lipcon via cos)

    HDFS-824. Stop lease checker in TestReadWhileWriting.  (szetszwo)

    HDFS-823. CheckPointer should use addInternalServlet for image-fetching
    servlet (jghoman)

    HDFS-456. Fix URI generation for windows file paths. (shv)

    HDFS-812. FSNamesystem#internalReleaseLease throws NullPointerException on
    a single-block file's lease recovery. (cos)

    HDFS-724. Pipeline hangs if one of the block receiver is not responsive.
    (hairong)

    HDFS-564. Adding pipeline tests 17-35. (hairong)

    HDFS-849. TestFiDataTransferProtocol2#pipeline_Fi_18 sometimes fails.
    (hairong)

    HDFS-762. Balancer causes Null Pointer Exception. 
    (Cristian Ivascu via dhruba)

    HDFS-868. Fix link to Hadoop Upgrade Wiki. (Chris A. Mattmann via shv)
    
    HDFS-880. TestNNLeaseRecovery fails on windows (cos, shv)

    HDFS-699. Primary datanode should compare replicas' on disk lengths.
    (hairong)

    HDFS-897. Fix a bug related to generation stamp comparison in 
    ReplicasMap. (suresh)

    HDFS-793. Data node should receive the whole packet ack message before it
    constructs and sends its own ack message for the packet. (hairong)

    HDFS-101. DFS write pipeline: DFSClient sometimes does not detect second
    datanode failure. (hairong)

    HDFS-822. Appends to already-finalized blocks can rename across volumes.
    (hairong)

    HDFS-1046. Fix Tomcat version in hdfsproxy/build.xml.  (Srikanth
    Sundarrajan via szetszwo)

    HDFS-1072. Fix TestReadWhileWriting failure. (Erik Steffl via shv)

    HDFS-913. Rename fault injection test TestRename.java to TestFiRename.java
    to include it in tests run by ant target run-test-hdfs-fault-inject.
    (suresh)
  
    HDFS-695. RaidNode should read in configuration from hdfs-site.xml.
    (dhruba)

    HDFS-726. Eclipse .classpath template has outdated jar files and is
    missing some new ones. (cos)

    HDFS-750. Fix build failure due to TestRename. (suresh)

    HDFS-712. Move libhdfs from mapreduce subproject to hdfs subproject.
    (Eli Collins via dhruba)

    HDFS-757. Enable Unit test for HDFS Raid. (dhruba)

    HDFS-611. Prevent DataNode heartbeat times from increasing even when
    the DataNode has many blocks to delete. (Zheng Shao via dhruba)

    HDFS-751. Fix TestCrcCorruption to pick up the correct datablocks to
    corrupt. (dhruba)
    
    HDFS-763. Fix slightly misleading report from DataBlockScanner 
    about corrupted scans. (dhruba)

    HDFS-727. bug setting block size hdfsOpenFile (Eli Collins via cos)

    HDFS-756. libhdfs unit tests do not run. (Eli Collins via cos)

    HDFS-783. libhdfs tests brakes code coverage runs with Clover (cos)

    HDFS-785. Add Apache license to several namenode unit tests. 
    (Ravi Phulari via jghoman)

    HDFS-802. Update Eclipse configuration to match changes to Ivy
    configuration (Edwin Chan via cos)

    HDFS-423. Unbreak FUSE build and fuse_dfs_wrapper.sh (Eli Collins via cos)

    HDFS-825. Build fails to pull latest hadoop-core-* artifacts (cos)

    HDFS-94. The Heap Size printed in the NameNode WebUI is accurate.
    (Dmytro Molkov via dhruba)

    HDFS-767. An improved retry policy when the DFSClient is unable to fetch a
    block from the datanode.  (Ning Zhang via dhruba)

    HDFS-775. FSDataset calls getCapacity() twice. (stevel)
    
    HDFS-885. Datanode toString() NPEs on null dnRegistration. (stevel)

    HDFS-877. Client-driven block verification not functioning. (Todd
    Lipcon via hairong)

    HDFS-630. In DFSOutputStream.nextBlockOutputStream(), the client can
    exclude specific datanodes when locating the next block.
    (Cosmin Lehene via Stack)

    HDFS-922. Remove unnecessary semicolon added by HDFS-877 that causes
    problems for Eclipse compilation. (jghoman)

    HDFS-927  DFSInputStream retries too many times for new block locations
    (Todd Lipcon via Stack)

    HDFS-938. Replace calls to UGI.getUserName() with UGI.getShortUserName()
    (jghoman)

    HDFS-894. DatanodeID.ipcPort is not updated when existing node 
    re-registers. (Todd Lipcon via tomwhite)

    HDFS-965. Split TestDelegationToken in to two parts and fix configuration
    to allow proxy users in the test. (Jitendra Pandey via omalley)

    HDFS-999. Secondary namenode should login using kerberos if security is 
    configured (boryas)

    HDFS-856. Hardcoded replication level for new files in fuse-dfs.
    (Brian Bockelman via tomwhite)

    HDFS-857. Incorrect type for fuse-dfs capacity can cause "df" to return
    negative values on 32-bit machines. (Brian Bockelman via tomwhite)

    HDFS-858. Incorrect return codes for fuse-dfs. (Brian Bockelman via
    tomwhite)

    HDFS-859. fuse-dfs utime behavior causes issues with tar.
    (Brian Bockelman via tomwhite)

    HDFS-861. fuse-dfs does not support O_RDWR. (Brian Bockelman via tomwhite)

    HDFS-961. dfs_readdir incorrectly parses paths. (Eli Collins via tomwhite)

    HDFS-1015. Fix intermittent failure in TestSecurityTokenEditLog.
    (Jitendra Nath Pandey via suresh)

    HDFS-939. libhdfs test is broken. (Eli Collins via tomwhite)
    
    HDFS-1074. hdfsproxy: Fix bugs in TestProxyUtil.  (Srikanth Sundarrajan
    via szetszwo)

    HDFS-481. hdfsproxy: Bug Fixes + HdfsProxy to use proxy user to
    impresonate the real user.  (Srikanth Sundarrajan via szetszwo)

    HDFS-482. Move HsftpFileSystem's ssl.client.do.not.authenticate.server
    configuration setting to ssl-client.xml.  (Srikanth Sundarrajan via
    szetszwo)

    HDFS-1010. hdfsproxy: Retrieve groups from UnixUserGroupInformation
    instead of LdapEntry.  (Srikanth Sundarrajan via szetszwo)

    HDFS-466. hdfs_write infinite loop when dfs fails and cannot write
    files > 2 GB. (Pete Wyckoff via tomwhite)

    HDFS-651. HDFS Docs - fix listing of docs in the doc menu.
    (Corinne Chandel via tomwhite)

    HDFS-1014. Error in reading delegation tokens from edit logs.
    (Jitendra Nath Pandey via jhoman)

    HDFS-1088. Prevent renaming a symbolik link to its target.
    (Eli Collins via suresh)

    HDFS-966. NameNode does not recovers lease when it is in safemode.
    (dhruba)

    HDFS-833. Datanode shutdown should log problems with Storage.unlockAll()
    (Steve Loughran via dhruba)

    HDFS-1101. TestDiskError.testLocalDirs() fails. (cdouglas via jghoman)

    HDFS-1031. Enhance the webUi to list a few of the corrupted files in HDFS.
    (Andre Orian via dhruba)

    HDFS-1078. Create static and dynamic versions of libhdfs.
    (Sam Rash via dhruba)

    HDFS-1104. Fsck triggers full GC on NameNode. (hairong)

    HDFS-1141. Closing a file is successful only if the client still has a
    valid lease. (Todd Lipcon via dhruba)

    HDFS-1138. Prevent erroneous updation of modification time of a directory
    when fsimage loads. (Dmytro Molkov via dhruba)

    HDFS-1000. Updates libhdfs to the new API for UGI (ddas)

    HDFS-609. Create a file with the append flag does not work in HDFS.
    (tomwhite)

    HDFS-1255. Fix failing test-libhdfs.sh test. (tomwhite)

    HDFS-1256. libhdfs is missing from the tarball. (tomwhite)

    HDFS-1057. Concurrent readers hit ChecksumExceptions if following a
    writer to very end of file. (sam rash via hairong)

    HDFS-1212. Harmonize HDFS JAR library versions with Common. (tomwhite)

    HDFS-1159. clean-cache target removes wrong ivy cache (cos)

    HDFS-1193. -mvn-system-deploy target is broken which inturn fails the
    mvn-deploy task leading to unstable mapreduce build (Giridharan
    Kesavan via cos)

    HDFS-1299. 'compile-fault-inject' never should be called directly. (cos)

    HDFS-1311. Running tests with 'testcase' cause triple execution of the
    same test case (Cos)

    HDFS-1267. fuse-dfs does not compile. (Devaraj Das via tomwhite)

    HDFS-1598.  Directory listing on hftp:// does not show .*.crc files.
    (szetszwo)

    HDFS-1750. ListPathsServlet should not use HdfsFileStatus.getLocalName()
    to get file name since it may return an empty string.  (szetszwo)

Release 0.20.3 - Unreleased

  IMPROVEMENTS

  BUG FIXES

    HDFS-1041. DFSClient.getFileChecksum(..) should retry if connection to
    the first datanode fails.  (szetszwo)

    HDFS-909. Wait until edits syncing is finishes before purging edits.
    (Todd Lipcon via shv)

    HDFS-1258. Clearing namespace quota on "/" corrupts fs image.
    (Aaron T. Myers via szetszwo)

    HDFS-1406. TestCLI fails on Ubuntu with default /etc/hosts. (cos)

Release 0.20.203.0 - 2011-5-11

  IMPROVEMENTS

    HADOOP-7259. Contrib modules should include the build.properties from
    the enclosing hadoop directory. (omalley)

  BUG FIXES

    HDFS-132. Fix namenode to not report files deleted metrics for deletions
    done while replaying edits during startup. (suresh & shv)

    HDFS-955. New implementation of saveNamespace() to avoid loss of edits 
    when name-node fails during saving. (shv)

Release 0.20.2 - 2009-09-01

  IMPROVEMENTS

    HDFS-737. Add full path name of the file to the block information and 
    summary of total number of files, blocks, live and deadnodes to 
    metasave output. (Jitendra Nath Pandey via suresh)

    HDFS-919. Create test to validate the BlocksVerified metric (Gary Murry
    via cos)

    HDFS-907. Add tests for getBlockLocations and totalLoad metrics.
    (Ravi Phulari via cos)
    
  BUG FIXES

    HDFS-686. NullPointerException is thrown while merging edit log and image.
    (hairong)

    HDFS-677. Rename failure when both source and destination quota exceeds
    results in deletion of source. (suresh)

    HDFS-709. Fix TestDFSShell failure due to rename bug introduced by 
    HDFS-677. (suresh)

    HDFS-579. Fix DfsTask to follow the semantics of 0.19, regarding non-zero
    return values as failures. (Christian Kunz via cdouglas)

    HDFS-723. Fix deadlock in DFSClient#DFSOutputStream. (hairong)

    HDFS-596. Fix memory leak in hdfsFreeFileInfo() for libhdfs.
    (Zhang Bingjun via dhruba)

    HDFS-185. Disallow chown, chgrp, chmod, setQuota, and setSpaceQuota when
    name-node is in safemode. (Ravi Phulari via shv)

    HDFS-187. Initialize secondary namenode http address in TestStartup.
    (Todd Lipcon via szetszwo)

    HDFS-464. Fix memory leaks in libhdfs. (Christian Kunz via suresh)
    
    HDFS-1377. Quota bug for partial blocks allows quotas to be violated. (eli)

Release 0.20.1 - 2009-09-01

  IMPROVEMENTS

    HDFS-438. Improve help message for space quota command. (Raghu Angadi)

  BUG FIXES

    HDFS-167. Fix a bug in DFSClient that caused infinite retries on write.
    (Bill Zeller via szetszwo)

    HDFS-527. Remove/deprecate unnecessary DFSClient constructors.  (szetszwo)

    HDFS-525. The SimpleDateFormat object in ListPathsServlet is not thread
    safe. (Suresh Srinivas and cdouglas)

    HDFS-761. Fix failure to process rename operation from edits log due to 
    quota verification. (suresh)