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Hadoop: CLI MiniCluster.
========================

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Purpose
-------

Using the CLI MiniCluster, users can simply start and stop a single-node Hadoop cluster with a single command, and without the need to set any environment variables or manage configuration files. The CLI MiniCluster starts both a `YARN`/`MapReduce` & `HDFS` clusters.

This is useful for cases where users want to quickly experiment with a real Hadoop cluster or test non-Java programs that rely on significant Hadoop functionality.

Hadoop Tarball
--------------

You should be able to obtain the Hadoop tarball from the release. Also, you can directly create a tarball from the source:

    $ mvn clean install -DskipTests
    $ mvn package -Pdist -Dtar -DskipTests -Dmaven.javadoc.skip

**NOTE:** You will need [protoc 2.5.0](http://code.google.com/p/protobuf/) installed.

The tarball should be available in `hadoop-dist/target/` directory.

Running the MiniCluster
-----------------------

From inside the root directory of the extracted tarball, you can start the CLI MiniCluster using the following command:

    $ bin/mapred minicluster -rmport RM_PORT -jhsport JHS_PORT

In the example command above, `RM_PORT` and `JHS_PORT` should be replaced by the user's choice of these port numbers. If not specified, random free ports will be used.

There are a number of command line arguments that the users can use to control which services to start, and to pass other configuration properties. The available command line arguments:

    $ -D <property=value>    Options to pass into configuration object
    $ -datanodes <arg>       How many datanodes to start (default 1)
    $ -format                Format the DFS (default false)
    $ -help                  Prints option help.
    $ -jhsport <arg>         JobHistoryServer port (default 0--we choose)
    $ -namenode <arg>        URL of the namenode (default is either the DFS
    $                        cluster or a temporary dir)
    $ -nnport <arg>          NameNode port (default 0--we choose)
    $ -nnhttpport <arg>      NameNode HTTP port (default 0--we choose)
    $ -nodemanagers <arg>    How many nodemanagers to start (default 1)
    $ -nodfs                 Don't start a mini DFS cluster
    $ -nomr                  Don't start a mini MR cluster
    $ -rmport <arg>          ResourceManager port (default 0--we choose)
    $ -writeConfig <path>    Save configuration to this XML file.
    $ -writeDetails <path>   Write basic information to this JSON file.

To display this full list of available arguments, the user can pass the `-help` argument to the above command.