conf/hadoop-default.xml

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<!-- Do not modify this file directly.  Instead, copy entries that you -->
<!-- wish to modify from this file into hadoop-site.xml and change them -->
<!-- there.  If hadoop-site.xml does not already exist, create it.      -->

<configuration>

<!--- global properties -->

<property>
  <name>hadoop.tmp.dir</name>
  <value>/tmp/hadoop-${user.name}</value>
  <description>A base for other temporary directories.</description>
</property>


<!--- logging properties -->

<property>
  <name>hadoop.logfile.size</name>
  <value>10000000</value>
  <description>The max size of each log file</description>
</property>

<property>
  <name>hadoop.logfile.count</name>
  <value>10</value>
  <description>The max number of log files</description>
</property>

<property>
  <name>dfs.namenode.logging.level</name>
  <value>info</value>
  <description>The logging level for dfs namenode. Other values are "dir"(trac
e namespace mutations), "block"(trace block under/over replications and block
creations/deletions), or "all".</description>
</property>

<!-- i/o properties -->

<property>
  <name>io.sort.factor</name>
  <value>10</value>
  <description>The number of streams to merge at once while sorting
  files.  This determines the number of open file handles.</description>
</property>

<property>
  <name>io.sort.mb</name>
  <value>100</value>
  <description>The total amount of buffer memory to use while sorting 
  files, in megabytes.  By default, gives each merge stream 1MB, which
  should minimize seeks.</description>
</property>

<property>
  <name>io.file.buffer.size</name>
  <value>4096</value>
  <description>The size of buffer for use in sequence files.
  The size of this buffer should probably be a multiple of hardware
  page size (4096 on Intel x86), and it determines how much data is
  buffered during read and write operations.</description>
</property>
  
<property>
  <name>io.bytes.per.checksum</name>
  <value>512</value>
  <description>The number of bytes per checksum.  Must not be larger than
  io.file.buffer.size.</description>
</property>

<property>
  <name>io.skip.checksum.errors</name>
  <value>false</value>
  <description>If true, when a checksum error is encountered while
  reading a sequence file, entries are skipped, instead of throwing an
  exception.</description>
</property>
  
<property>
  <name>io.map.index.skip</name>
  <value>0</value>
  <description>Number of index entries to skip between each entry.
  Zero by default. Setting this to values larger than zero can
  facilitate opening large map files using less memory.</description>
</property>

<property>
  <name>io.compression.codecs</name>
  <value>org.apache.hadoop.io.compress.DefaultCodec,org.apache.hadoop.io.compress.GzipCodec</value>
  <description>A list of the compression codec classes that can be used 
               for compression/decompression.</description>
</property>

<!-- file system properties -->

<property>
  <name>fs.default.name</name>
  <value>file:///</value>
  <description>The name of the default file system.  A URI whose
  scheme and authority determine the FileSystem implementation.  The
  uri's scheme determines the config property (fs.SCHEME.impl) naming
  the FileSystem implementation class.  The uri's authority is used to
  determine the host, port, etc. for a filesystem.</description>
</property>

<property>
  <name>fs.trash.root</name>
  <value>${hadoop.tmp.dir}/Trash</value>
  <description>The trash directory, used by FsShell's 'rm' command.
  </description>
</property>

<property>
  <name>fs.trash.interval</name>
  <value>0</value>
  <description>Number of minutes between trash checkpoints.
  If zero, the trash feature is disabled.
  </description>
</property>

<property>
  <name>fs.file.impl</name>
  <value>org.apache.hadoop.fs.LocalFileSystem</value>
  <description>The FileSystem for file: uris.</description>
</property>

<property>
  <name>fs.hdfs.impl</name>
  <value>org.apache.hadoop.dfs.DistributedFileSystem</value>
  <description>The FileSystem for hdfs: uris.</description>
</property>

<property>
  <name>fs.s3.impl</name>
  <value>org.apache.hadoop.fs.s3.S3FileSystem</value>
  <description>The FileSystem for s3: uris.</description>
</property>

<property>
  <name>fs.ramfs.impl</name>
  <value>org.apache.hadoop.fs.InMemoryFileSystem</value>
  <description>The FileSystem for ramfs: uris.</description>
</property>

<property>
  <name>fs.inmemory.size.mb</name>
  <value>75</value>
  <description>The size of the in-memory filsystem instance in MB</description>
</property>

<property>
  <name>fs.checkpoint.dir</name>
  <value>${hadoop.tmp.dir}/dfs/namesecondary</value>
  <description>Determines where on the local filesystem the DFS secondary
      name node should store the temporary images and edits to merge.  
  </description>
</property>

<property>
  <name>fs.checkpoint.period</name>
  <value>3600</value>
  <description>The number of seconds between two periodic checkpoints.
  </description>
</property>

<property>
  <name>fs.checkpoint.size</name>
  <value>67108864</value>
  <description>The size of the current edit log (in bytes) that triggers
       a periodic checkpoint even if the fs.checkpoint.period hasn't expired.
  </description>
</property>

<property>
  <name>dfs.secondary.info.port</name>
  <value>50090</value>
  <description>The base number for the Secondary namenode info port.
  </description>
</property>

<property>
  <name>dfs.secondary.info.bindAddress</name>
  <value>0.0.0.0</value>
  <description>
    The address where the secondary namenode web UI will listen to.
  </description>
</property>

<property>
  <name>dfs.datanode.bindAddress</name>
  <value>0.0.0.0</value>
  <description>
    the address where the datanode will listen to.
  </description>
</property>

<property>
  <name>dfs.datanode.port</name>
  <value>50010</value>
  <description>The port number that the dfs datanode server uses as a starting 
	       point to look for a free port to listen on.
</description>
</property>

<property>
  <name>dfs.info.bindAddress</name>
  <value>0.0.0.0</value>
  <description>
    the address where the dfs namenode web ui will listen on.
  </description>
</property>

<property>
  <name>dfs.info.port</name>
  <value>50070</value>
  <description>The base port number for the dfs namenode web ui.
  </description>
</property>

 <property>
  <name>dfs.datanode.dns.interface</name>
  <value>default</value>
  <description>The name of the Network Interface from which a data node should 
  report its IP address.
  </description>
 </property>
 
<property>
  <name>dfs.datanode.dns.nameserver</name>
  <value>default</value>
  <description>The host name or IP address of the name server (DNS)
  which a DataNode should use to determine the host name used by the
  NameNode for communication and display purposes.
  </description>
 </property>
 
<property>
  <name>dfs.default.chunk.view.size</name>
  <value>32768</value>
  <description>The number of bytes to view for a file on the browser.
  </description>
</property>

<property>
  <name>dfs.datanode.du.reserved</name>
  <value>0</value>
  <description>Reserved space in bytes. Always leave this much space free for non dfs use
  </description>
</property>

<property>
  <name>dfs.datanode.du.pct</name>
  <value>0.98f</value>
  <description>When calculating remaining space, only use this percentage of the real available space
  </description>
</property>

<property>
  <name>dfs.name.dir</name>
  <value>${hadoop.tmp.dir}/dfs/name</value>
  <description>Determines where on the local filesystem the DFS name node
      should store the name table.  If this is a comma-delimited list
      of directories then the name table is replicated in all of the
      directories, for redundancy. </description>
</property>

<property>
  <name>dfs.client.buffer.dir</name>
  <value>${hadoop.tmp.dir}/dfs/tmp</value>
  <description>Determines where on the local filesystem an DFS client
  should store its blocks before it sends them to the datanode.
  </description>
</property>

<property>
  <name>dfs.data.dir</name>
  <value>${hadoop.tmp.dir}/dfs/data</value>
  <description>Determines where on the local filesystem an DFS data node
  should store its blocks.  If this is a comma-delimited
  list of directories, then data will be stored in all named
  directories, typically on different devices.
  Directories that do not exist are ignored.
  </description>
</property>

<property>
  <name>dfs.replication</name>
  <value>3</value>
  <description>Default block replication. 
  The actual number of replications can be specified when the file is created.
  The default is used if replication is not specified in create time.
  </description>
</property>

<property>
  <name>dfs.replication.max</name>
  <value>512</value>
  <description>Maximal block replication. 
  </description>
</property>

<property>
  <name>dfs.replication.min</name>
  <value>1</value>
  <description>Minimal block replication. 
  </description>
</property>

<property>
  <name>dfs.block.size</name>
  <value>67108864</value>
  <description>The default block size for new files.</description>
</property>

<property>
  <name>dfs.df.interval</name>
  <value>3000</value>
  <description>Disk usage statistics refresh interval in msec.</description>
</property>

<property>
  <name>dfs.client.block.write.retries</name>
  <value>3</value>
  <description>The number of retries for writing blocks to the data nodes, 
  before we signal failure to the application.
  </description>
</property>

<property>
  <name>dfs.blockreport.intervalMsec</name>
  <value>3600000</value>
  <description>Determines block reporting interval in milliseconds.</description>
</property>

<property>
  <name>dfs.heartbeat.interval</name>
  <value>3</value>
  <description>Determines datanode heartbeat interval in seconds.</description>
</property>

<property>
  <name>dfs.safemode.threshold.pct</name>
  <value>0.999f</value>
  <description>
  	Specifies the percentage of blocks that should satisfy 
  	the minimal replication requirement defined by dfs.replication.min.
  	Values less than or equal to 0 mean not to start in safe mode.
  	Values greater than 1 will make safe mode permanent.
 	</description>
</property>

<property>
  <name>dfs.safemode.extension</name>
  <value>30000</value>
  <description>
  	Determines extension of safe mode in milliseconds 
  	after the threshold level is reached.
 	</description>
</property>

<property>
  <name>dfs.network.script</name>
  <value></value>
  <description>
        Specifies a script name that print the network location path
        of the current machine.
  </description>
</property>

<property>
  <name>dfs.hosts</name>
  <value></value>
  <description>Names a file that contains a list of hosts that are
  permitted to connect to the namenode. The full pathname of the file
  must be specified.  If the value is empty, all hosts are
  permitted.</description>
</property>

<property>
  <name>dfs.hosts.exclude</name>
  <value></value>
  <description>Names a file that contains a list of hosts that are
  not permitted to connect to the namenode.  The full pathname of the
  file must be specified.  If the value is empty, no hosts are
  excluded.</description>
</property> 

<property>
  <name>fs.s3.block.size</name>
  <value>67108864</value>
  <description>Block size to use when writing files to S3.</description>
</property>

<property>
  <name>fs.s3.buffer.dir</name>
  <value>${hadoop.tmp.dir}/s3</value>
  <description>Determines where on the local filesystem the S3 filesystem
  should store its blocks before it sends them to S3
  or after it retrieves them from S3.
  </description>
</property>

<property>
  <name>fs.s3.maxRetries</name>
  <value>4</value>
  <description>The maximum number of retries for reading or writing blocks to S3, 
  before we signal failure to the application.
  </description>
</property>

<property>
  <name>fs.s3.sleepTimeSeconds</name>
  <value>10</value>
  <description>The number of seconds to sleep between each S3 retry.
  </description>
</property>

<!-- map/reduce properties -->

<property>
  <name>mapred.job.tracker</name>
  <value>local</value>
  <description>The host and port that the MapReduce job tracker runs
  at.  If "local", then jobs are run in-process as a single map
  and reduce task.
  </description>
</property>

<property>
  <name>mapred.job.tracker.info.bindAddress</name>
  <value>0.0.0.0</value>
  <description>
    the address where the job tracker info webserver will be binded on.
  </description>
</property>

<property>
  <name>mapred.job.tracker.info.port</name>
  <value>50030</value>
  <description>The port that the MapReduce job tracker info webserver runs at.
  </description>
</property>

<property>
  <name>mapred.task.tracker.report.bindAddress</name>
  <value>0.0.0.0</value>
  <description>
    the address where the maperd tracker report server will be binded on.
  </description>
</property>

<property>
  <name>mapred.task.tracker.report.port</name>
  <value>50050</value>
  <description>The port number that the MapReduce task tracker report server uses as a starting
               point to look for a free port to listen on.
  </description>
</property>

<property>
  <name>mapred.local.dir</name>
  <value>${hadoop.tmp.dir}/mapred/local</value>
  <description>The local directory where MapReduce stores intermediate
  data files.  May be a comma-separated list of
  directories on different devices in order to spread disk i/o.
  Directories that do not exist are ignored.
  </description>
</property>

<property>
  <name>local.cache.size</name>
  <value>10737418240</value>
  <description>The limit on the size of cache you want to keep, set by default
  to 10GB. This will act as a soft limit on the cache directory for out of band data.
  </description>
</property>
            
<property>
  <name>mapred.system.dir</name>
  <value>${hadoop.tmp.dir}/mapred/system</value>
  <description>The shared directory where MapReduce stores control files.
  </description>
</property>

<property>
  <name>mapred.temp.dir</name>
  <value>${hadoop.tmp.dir}/mapred/temp</value>
  <description>A shared directory for temporary files.
  </description>
</property>

<property>
  <name>mapred.local.dir.minspacestart</name>
  <value>0</value>
  <description>If the space in mapred.local.dir drops under this, 
  do not ask for more tasks.
  Value in bytes.
  </description>
</property>

<property>
  <name>mapred.local.dir.minspacekill</name>
  <value>0</value>
  <description>If the space in mapred.local.dir drops under this, 
  	do not ask more tasks until all the current ones have finished and 
  	cleaned up. Also, to save the rest of the tasks we have running, 
  	kill one of them, to clean up some space. Start with the reduce tasks,
  	then go with the ones that have finished the least.
  	Value in bytes.
  </description>
</property>

<property>
  <name>mapred.map.tasks</name>
  <value>2</value>
  <description>The default number of map tasks per job.  Typically set
  to a prime several times greater than number of available hosts.
  Ignored when mapred.job.tracker is "local".  
  </description>
</property>

<property>
  <name>mapred.reduce.tasks</name>
  <value>1</value>
  <description>The default number of reduce tasks per job.  Typically set
  to a prime close to the number of available hosts.  Ignored when
  mapred.job.tracker is "local".
  </description>
</property>

<property>
  <name>mapred.reduce.parallel.copies</name>
  <value>5</value>
  <description>The default number of parallel transfers run by reduce
  during the copy(shuffle) phase.
  </description>
</property>

<property>
  <name>mapred.task.timeout</name>
  <value>600000</value>
  <description>The number of milliseconds before a task will be
  terminated if it neither reads an input, writes an output, nor
  updates its status string.
  </description>
</property>

<property>
  <name>mapred.tasktracker.tasks.maximum</name>
  <value>2</value>
  <description>The maximum number of tasks that will be run
  simultaneously by a task tracker.
  </description>
</property>

<property>
  <name>mapred.child.java.opts</name>
  <value>-Xmx200m</value>
  <description>Java opts for the task tracker child processes.  Subsumes
  'mapred.child.heap.size' (If a mapred.child.heap.size value is found
  in a configuration, its maximum heap size will be used and a warning
  emitted that heap.size has been deprecated). Also, the following symbols,
  if present, will be interpolated: @taskid@ is replaced by current TaskID;
  and @port@ will be replaced by mapred.task.tracker.report.port + 1 (A second
  child will fail with a port-in-use if mapred.tasktracker.tasks.maximum is
  greater than one). Any other occurrences of '@' will go unchanged. For
  example, to enable verbose gc logging to a file named for the taskid in
  /tmp and to set the heap maximum to be a gigabyte, pass a 'value' of:

        -Xmx1024m -verbose:gc -Xloggc:/tmp/@taskid@.gc
  </description>
</property>

<property>
  <name>mapred.inmem.merge.threshold</name>
  <value>1000</value>
  <description>The threshold, in terms of the number of files 
  for the in-memory merge process. When we accumulate threshold number of files
  we initiate the in-memory merge and spill to disk. A value of 0 or less than
  0 indicates we want to DON'T have any threshold and instead depend only on
  the ramfs's memory consumption to trigger the merge.
  </description>
</property>

<property>
  <name>mapred.speculative.execution</name>
  <value>false</value>
  <description>If true, then multiple instances of some map and reduce tasks 
               may be executed in parallel.</description>
</property>

<property>
  <name>mapred.min.split.size</name>
  <value>0</value>
  <description>The minimum size chunk that map input should be split
  into.  Note that some file formats may have minimum split sizes that
  take priority over this setting.</description>
</property>

<property>
  <name>mapred.submit.replication</name>
  <value>10</value>
  <description>The replication level for submitted job files.  This
  should be around the square root of the number of nodes.
  </description>
</property>


<property>
  <name>mapred.tasktracker.dns.interface</name>
  <value>default</value>
  <description>The name of the Network Interface from which a task
  tracker should report its IP address.
  </description>
 </property>
 
<property>
  <name>mapred.tasktracker.dns.nameserver</name>
  <value>default</value>
  <description>The host name or IP address of the name server (DNS)
  which a TaskTracker should use to determine the host name used by
  the JobTracker for communication and display purposes.
  </description>
 </property>
 
<property>
  <name>tasktracker.http.threads</name>
  <value>40</value>
  <description>The number of worker threads that for the http server. This is
               used for map output fetching
  </description>
</property>

<property>
  <name>tasktracker.http.bindAddress</name>
  <value>0.0.0.0</value>
  <description>
    the address where the task tracker http server will be binded on.
  </description>
</property>

<property>
  <name>tasktracker.http.port</name>
  <value>50060</value>
  <description>The default port for task trackers to use as their http server.
  </description>
</property>

<property>
  <name>keep.failed.task.files</name>
  <value>false</value>
  <description>Should the files for failed tasks be kept. This should only be 
               used on jobs that are failing, because the storage is never
               reclaimed. It also prevents the map outputs from being erased
               from the reduce directory as they are consumed.</description>
</property>

<!-- 
  <property>
  <name>keep.task.files.pattern</name>
  <value>.*_m_123456_0</value>
  <description>Keep all files from tasks whose task names match the given
               regular expression. Defaults to none.</description>
  </property>
-->

<property>
  <name>mapred.output.compress</name>
  <value>false</value>
  <description>Should the outputs of the reduces be compressed?
  </description>
</property>

<property>
  <name>mapred.output.compression.codec</name>
  <value>org.apache.hadoop.io.compress.DefaultCodec</value>
  <description>If the reduce outputs are compressed, how should they be 
               compressed?
  </description>
</property>

<property>
  <name>mapred.compress.map.output</name>
  <value>false</value>
  <description>Should the outputs of the maps be compressed before being
               sent across the network. Uses SequenceFile compression.
  </description>
</property>

<property>
  <name>io.seqfile.compress.blocksize</name>
  <value>1000000</value>
  <description>The minimum block size for compression in block compressed 
  				SequenceFiles.
  </description>
</property>

<property>
  <name>io.seqfile.lazydecompress</name>
  <value>true</value>
  <description>Should values of block-compressed SequenceFiles be decompressed
  				only when necessary.
  </description>
</property>

<property>
  <name>io.seqfile.sorter.recordlimit</name>
  <value>1000000</value>
  <description>The limit on number of records to be kept in memory in a spill 
  				in SequenceFiles.Sorter
  </description>
</property>

<property>
  <name>io.seqfile.compression.type</name>
  <value>RECORD</value>
  <description>The default compression type for SequenceFile.Writer.
  </description>
</property>

<property>
  <name>map.sort.class</name>
  <value>org.apache.hadoop.mapred.MergeSorter</value>
  <description>The default sort class for sorting keys.
  </description>
</property>

<property>
  <name>mapred.userlog.num.splits</name>
  <value>4</value>
  <description>The number of fragments into which the user-log is to be split.
  </description>
</property>

<property>
  <name>mapred.userlog.limit.kb</name>
  <value>100</value>
  <description>The maximum size of user-logs of each task.
  </description>
</property>

<property>
  <name>mapred.userlog.purgesplits</name>
  <value>true</value>
  <description>Should the splits be purged disregarding the user-log size limit.
  </description>
</property>

<property>
  <name>mapred.userlog.retain.hours</name>
  <value>12</value>
  <description>The maximum time, in hours, for which the user-logs are to be 
  				retained.
  </description>
</property>

<property>
  <name>mapred.hosts</name>
  <value></value>
  <description>Names a file that contains the list of nodes that may
  connect to the jobtracker.  If the value is empty, all hosts are
  permitted.</description>
</property>

<property>
  <name>mapred.hosts.exclude</name>
  <value></value>
  <description>Names a file that contains the list of hosts that
  should be excluded by the jobtracker.  If the value is empty, no
  hosts are excluded.</description>
</property> 

<property>
  <name>mapred.max.tracker.failures</name>
  <value>4</value>
  <description>The number of task-failures on a tasktracker of a given job 
               after which new tasks of that job aren't assigned to it.
  </description>
</property>

<property>
  <name>jobclient.output.filter</name>
  <value>FAILED</value>
  <description>The filter for controlling the output of the task's userlogs sent
               to the console of the JobClient. 
               The permissible options are: NONE, FAILED, SUCCEEDED and ALL.
  </description>
</property>

<!-- ipc properties -->

<property>
  <name>ipc.client.timeout</name>
  <value>60000</value>
  <description>Defines the timeout for IPC calls in milliseconds.</description>
</property>

<property>
  <name>ipc.client.idlethreshold</name>
  <value>4000</value>
  <description>Defines the threshold number of connections after which
               connections will be inspected for idleness.
  </description>
</property>

<property>
  <name>ipc.client.maxidletime</name>
  <value>120000</value>
  <description>Defines the maximum idle time for a connected client after 
               which it may be disconnected.
  </description>
</property>

<property>
  <name>ipc.client.kill.max</name>
  <value>10</value>
  <description>Defines the maximum number of clients to disconnect in one go.
  </description>
</property>

<property>
  <name>ipc.client.connection.maxidletime</name>
  <value>1000</value>
  <description>The maximum time after which a client will bring down the
               connection to the server.
  </description>
</property>

<property>
  <name>ipc.client.connect.max.retries</name>
  <value>10</value>
  <description>Indicates the number of retries a client will make to establish
               a server connection.
  </description>
</property>

<property>
  <name>ipc.server.listen.queue.size</name>
  <value>128</value>
  <description>Indicates the length of the listen queue for servers accepting
               client connections.
  </description>
</property>

</configuration>