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  ---
  Single Node Setup
  ---
  ---
  ${maven.build.timestamp}

Single Node Setup

%{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.

** Required Software

   Required software for Linux and Windows include:

    [[1]] Java^TM 1.6.x, preferably from Sun, must be installed.

    [[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 Apache Download Mirrors.

* Prepare to Start the Hadoop Cluster

   Unpack the downloaded Hadoop distribution. In the distribution, edit
   the file <<<conf/hadoop-env.sh>>> to define at least <<<JAVA_HOME>>> to be the root
   of your Java installation.

   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:

     * Local (Standalone) Mode

     * Pseudo-Distributed Mode

     * 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 conf/*.xml input
   $ bin/hadoop jar hadoop-*-examples.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:

   conf/core-site.xml:

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

   conf/hdfs-site.xml:

----
<configuration>
     <property>
         <name>dfs.replication</name>
         <value>1</value>
     </property>
</configuration>
----

   conf/mapred-site.xml:

----
<configuration>
     <property>
         <name>mapred.job.tracker</name>
         <value>localhost:9001</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

   Format a new distributed-filesystem:

----
   $ bin/hadoop namenode -format
----

   Start the hadoop daemons:

----
   $ bin/start-all.sh
----

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

   Browse the web interface for the NameNode and the JobTracker; by
   default they are available at:

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

     * JobTracker - <<<http://localhost:50030/>>>

   Copy the input files into the distributed filesystem:

----
   $ bin/hadoop fs -put conf input
----

   Run some of the examples provided:

----
   $ bin/hadoop jar hadoop-*-examples.jar grep input output 'dfs[a-z.]+'
----

   Examine the output files:

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

----
   $ bin/hadoop fs -get output output
   $ cat output/*
----

   or

   View the output files on the distributed filesystem:

----
   $ bin/hadoop fs -cat output/*
----

   When you're done, stop the daemons with:

----
   $ bin/stop-all.sh
----

* Fully-Distributed Operation

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

   Java and JNI are trademarks or registered trademarks of Sun
   Microsystems, Inc. in the United States and other countries.