hadoop-common-project/hadoop-common/src/site/apt/SingleCluster.apt.vm

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  ---
  Hadoop MapReduce Next Generation ${project.version} - Setting up a Single Node Cluster.
  ---
  ---
  ${maven.build.timestamp}

Hadoop MapReduce Next Generation - Setting up a Single Node Cluster.

%{toc|section=1|fromDepth=0}

* Purpose

  This document describes how to set up and configure a single-node Hadoop
  installation so that you can quickly perform simple operations using Hadoop
  MapReduce and the Hadoop Distributed File System (HDFS).

* Prerequisites

** Supported Platforms

   * GNU/Linux is supported as a development and production platform.
     Hadoop has been demonstrated on GNU/Linux clusters with 2000 nodes.

   * Windows is also a supported platform but the followings steps
     are for Linux only. To set up Hadoop on Windows, see
     {{{http://wiki.apache.org/hadoop/Hadoop2OnWindows}wiki page}}.

** Required Software

   Required software for Linux include:

   [[1]] Java\u2122 must be installed. Recommended Java versions are described
         at {{{http://wiki.apache.org/hadoop/HadoopJavaVersions}
         HadoopJavaVersions}}.

   [[2]] ssh must be installed and sshd must be running to use the Hadoop
         scripts that manage remote Hadoop daemons.

** Installing Software

  If your cluster doesn't have the requisite software you will need to install
  it.

  For example on Ubuntu Linux:

----
  $ sudo apt-get install ssh
  $ sudo apt-get install rsync
----

* Download

  To get a Hadoop distribution, download a recent stable release from one of
  the {{{http://www.apache.org/dyn/closer.cgi/hadoop/common/}
  Apache Download Mirrors}}.

* Prepare to Start the Hadoop Cluster

  Unpack the downloaded Hadoop distribution. In the distribution, edit
  the file <<<etc/hadoop/hadoop-env.sh>>> to define some parameters as
  follows:

----
  # set to the root of your Java installation
  export JAVA_HOME=/usr/java/latest

  # Assuming your installation directory is /usr/local/hadoop
  export HADOOP_PREFIX=/usr/local/hadoop
----

  Try the following command:

----
  $ bin/hadoop
----

  This will display the usage documentation for the hadoop script.

  Now you are ready to start your Hadoop cluster in one of the three supported
  modes:

   * {{{Standalone Operation}Local (Standalone) Mode}}

   * {{{Pseudo-Distributed Operation}Pseudo-Distributed Mode}}

   * {{{Fully-Distributed Operation}Fully-Distributed Mode}}

* Standalone Operation

  By default, Hadoop is configured to run in a non-distributed mode, as a
  single Java process. This is useful for debugging.

  The following example copies the unpacked conf directory to use as input
  and then finds and displays every match of the given regular expression.
  Output is written to the given output directory.

----
  $ mkdir input
  $ cp etc/hadoop/*.xml input
  $ bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-${project.version}.jar grep input output 'dfs[a-z.]+'
  $ cat output/*
----

* Pseudo-Distributed Operation

  Hadoop can also be run on a single-node in a pseudo-distributed mode where
  each Hadoop daemon runs in a separate Java process.

** Configuration

  Use the following:

  etc/hadoop/core-site.xml:

+---+
<configuration>
    <property>
        <name>fs.defaultFS</name>
        <value>hdfs://localhost:9000</value>
    </property>
</configuration>
+---+

  etc/hadoop/hdfs-site.xml:
  
+---+
<configuration>
    <property>
        <name>dfs.replication</name>
        <value>1</value>
    </property>
</configuration>
+---+

** Setup passphraseless ssh

  Now check that you can ssh to the localhost without a passphrase:

----
  $ ssh localhost
----

  If you cannot ssh to localhost without a passphrase, execute the
  following commands:

----
  $ ssh-keygen -t dsa -P '' -f ~/.ssh/id_dsa
  $ cat ~/.ssh/id_dsa.pub >> ~/.ssh/authorized_keys
----

** Execution

  The following instructions are to run a MapReduce job locally.
  If you want to execute a job on YARN, see {{YARN on Single Node}}.

  [[1]] Format the filesystem:

----
  $ bin/hdfs namenode -format
----

  [[2]] Start NameNode daemon and DataNode daemon:

----
  $ sbin/start-dfs.sh
----

        The hadoop daemon log output is written to the <<<${HADOOP_LOG_DIR}>>>
        directory (defaults to <<<${HADOOP_HOME}/logs>>>).

  [[3]] Browse the web interface for the NameNode; by default it is
        available at:

        * NameNode - <<<http://localhost:50070/>>>

  [[4]] Make the HDFS directories required to execute MapReduce jobs:

----
  $ bin/hdfs dfs -mkdir /user
  $ bin/hdfs dfs -mkdir /user/<username>
----

  [[5]] Copy the input files into the distributed filesystem:

----
  $ bin/hdfs dfs -put etc/hadoop input
----

  [[6]] Run some of the examples provided:

----
  $ bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-${project.version}.jar grep input output 'dfs[a-z.]+'
----

  [[7]] Examine the output files:

        Copy the output files from the distributed filesystem to the local
        filesystem and examine them:

----
  $ bin/hdfs dfs -get output output
  $ cat output/*
----

        or

        View the output files on the distributed filesystem:

----
  $ bin/hdfs dfs -cat output/*
----

  [[8]] When you're done, stop the daemons with:

----
  $ sbin/stop-dfs.sh
----

** YARN on Single Node

  You can run a MapReduce job on YARN in a pseudo-distributed mode by setting
  a few parameters and running ResourceManager daemon and NodeManager daemon
  in addition.

  The following instructions assume that 1. ~ 4. steps of
  {{{Execution}the above instructions}} are already executed.

  [[1]] Configure parameters as follows:

        etc/hadoop/mapred-site.xml:

+---+
<configuration>
    <property>
        <name>mapreduce.framework.name</name>
        <value>yarn</value>
    </property>
</configuration>
+---+

        etc/hadoop/yarn-site.xml:

+---+
<configuration>
    <property>
        <name>yarn.nodemanager.aux-services</name>
        <value>mapreduce_shuffle</value>
    </property>
</configuration>
+---+

  [[2]] Start ResourceManager daemon and NodeManager daemon:

----
  $ sbin/start-yarn.sh
----

  [[3]] Browse the web interface for the ResourceManager; by default it is
        available at:

        * ResourceManager - <<<http://localhost:8088/>>>

  [[4]] Run a MapReduce job.

  [[5]] When you're done, stop the daemons with:

----
  $ sbin/stop-yarn.sh
----

* Fully-Distributed Operation

  For information on setting up fully-distributed, non-trivial clusters
  see {{{./ClusterSetup.html}Cluster Setup}}.