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<!DOCTYPE document PUBLIC "-//APACHE//DTD Documentation V2.0//EN" "http://forrest.apache.org/dtd/document-v20.dtd">

<document>
  
  <header>
    <title>Quick Start</title>
  </header>
  
  <body>
  
    <section>
      <title>Purpose</title>
      
      <p>The purpose of this document is to help you get a single-node Hadoop 
      installation up and running very quickly so that you can get a flavour
      of the Hadoop Distributed File System 
      (see <a href="hdfs_design.html"> <acronym title="Hadoop Distributed File System">HDFS</acronym> Architecture</a>) and 
      the Map/Reduce framework; that is, perform simple operations on HDFS and 
      run example jobs.</p>
    </section>
    
    <section id="PreReqs">
      <title>Pre-requisites</title>
      
      <section>
        <title>Supported Platforms</title>
        
        <ul>
          <li>
            GNU/Linux is supported as a development and production platform. 
            Hadoop has been demonstrated on GNU/Linux clusters with 2000 nodes.
          </li>
          <li>
            Win32 is supported as a <em>development platform</em>. Distributed 
            operation has not been well tested on Win32, so it is not 
            supported as a <em>production platform</em>.
          </li>
        </ul>        
      </section>
      
      <section>
        <title>Required Software</title>
        <p>Required software for Linux and Windows include:</p>
        <ol>
          <li>
            Java<sup>TM</sup> 1.6.x, preferably from Sun, must be installed.
          </li>
          <li>
            <strong>ssh</strong> must be installed and <strong>sshd</strong> must 
            be running to use the Hadoop scripts that manage remote Hadoop 
            daemons.
          </li>
        </ol>
        <p>Additional requirements for Windows include:</p>
        <ol>
          <li>
            <a href="http://www.cygwin.com/">Cygwin</a> - Required for shell 
            support in addition to the required software above. 
          </li>
        </ol>
      </section>

      <section>
        <title>Installing Software</title>
          
        <p>If your cluster doesn't have the requisite software you will need to
        install it.</p>
          
        <p>For example on Ubuntu Linux:</p>
        <p>
          <code>$ sudo apt-get install ssh</code><br/>
          <code>$ sudo apt-get install rsync</code>
        </p>
          
        <p>On Windows, if you did not install the required software when you 
        installed cygwin, start the cygwin installer and select the packages:</p>
        <ul>
          <li>openssh - the <em>Net</em> category</li>
        </ul>
      </section>
      
    </section>
    
    <section>
      <title>Download</title>
      
      <p>
        To get a Hadoop distribution, download a recent 
        <a href="ext:releases">stable release</a> from one of the Apache Download
        Mirrors.
      </p>
    </section>

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

	  <p>
	    Try the following command:<br/>
        <code>$ bin/hadoop</code><br/>
        This will display the usage documentation for the <strong>hadoop</strong> 
        script.
      </p>
      
      <p>Now you are ready to start your Hadoop cluster in one of the three supported
      modes:
      </p>
      <ul>
        <li>Local (Standalone) Mode</li>
        <li>Pseudo-Distributed Mode</li>
        <li>Fully-Distributed Mode</li>
      </ul>
    </section>
    
    <section id="Local">
      <title>Standalone Operation</title>
      
      <p>By default, Hadoop is configured to run in a non-distributed 
      mode, as a single Java process. This is useful for debugging.</p>
      
      <p>
        The following example copies the unpacked <code>conf</code> directory to 
        use as input and then finds and displays every match of the given regular 
        expression. Output is written to the given <code>output</code> directory.
        <br/>
        <code>$ mkdir input</code><br/>
        <code>$ cp conf/*.xml input</code><br/>
        <code>
          $ bin/hadoop jar hadoop-*-examples.jar grep input output 'dfs[a-z.]+'
        </code><br/>
        <code>$ cat output/*</code>
      </p>
    </section>
    
    <section id="PseudoDistributed">
      <title>Pseudo-Distributed Operation</title>

	  <p>Hadoop can also be run on a single-node in a pseudo-distributed mode 
	  where each Hadoop daemon runs in a separate Java process.</p>
	  
      <section>
        <title>Configuration</title>
        <p>Use the following:
        <br/>
        <code>conf/core-site.xml</code>:</p>
        <table>
        <tr><td>&lt;configuration&gt;</td></tr>

          <tr><td>&nbsp;&nbsp;&lt;property&gt;</td></tr>
            <tr><td>&nbsp;&nbsp;&nbsp;&nbsp;&lt;name&gt;fs.default.name&lt;/name&gt;</td></tr>
            <tr><td>&nbsp;&nbsp;&nbsp;&nbsp;&lt;value&gt;hdfs://localhost:9000&lt;/value&gt;</td></tr>
          <tr><td>&nbsp;&nbsp;&lt;/property&gt;</td></tr>

        <tr><td>&lt;/configuration&gt;</td></tr>
        </table>
      
        <p><br/><code>conf/hdfs-site.xml</code>:</p>
        <table>
        <tr><td>&lt;configuration&gt;</td></tr>

          <tr><td>&nbsp;&nbsp;&lt;property&gt;</td></tr>
            <tr><td>&nbsp;&nbsp;&nbsp;&nbsp;&lt;name&gt;dfs.replication&lt;/name&gt;</td></tr>
            <tr><td>&nbsp;&nbsp;&nbsp;&nbsp;&lt;value&gt;1&lt;/value&gt;</td></tr>
          <tr><td>&nbsp;&nbsp;&lt;/property&gt;</td></tr>

        <tr><td>&lt;/configuration&gt;</td></tr>
        </table>
      
        <p><br/><code>conf/mapred-site.xml</code>:</p>
        <table>
        <tr><td>&lt;configuration&gt;</td></tr>

          <tr><td>&nbsp;&nbsp;&lt;property&gt;</td></tr>
            <tr><td>&nbsp;&nbsp;&nbsp;&nbsp;&lt;name&gt;mapred.job.tracker&lt;/name&gt;</td></tr>
            <tr><td>&nbsp;&nbsp;&nbsp;&nbsp;&lt;value&gt;localhost:9001&lt;/value&gt;</td></tr>
          <tr><td>&nbsp;&nbsp;&lt;/property&gt;</td></tr>

        <tr><td>&lt;/configuration&gt;</td></tr>
        </table>
      </section>

      <section>
        <title>Setup passphraseless <em>ssh</em></title>
        
        <p>
          Now check that you can ssh to the localhost without a passphrase:<br/>
          <code>$ ssh localhost</code>
        </p>
        
        <p>
          If you cannot ssh to localhost without a passphrase, execute the 
          following commands:<br/>
   		  <code>$ ssh-keygen -t dsa -P '' -f ~/.ssh/id_dsa</code><br/>
		  <code>$ cat ~/.ssh/id_dsa.pub >> ~/.ssh/authorized_keys</code>
		</p>
      </section>
    
      <section>
        <title>Execution</title>
        
        <p>
          Format a new distributed-filesystem:<br/>
          <code>$ bin/hadoop namenode -format</code>
        </p>

		<p>
		  Start the hadoop daemons:<br/>
          <code>$ bin/start-all.sh</code>
        </p>

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

        <p>Browse the web interface for the NameNode and the JobTracker; by
        default they are available at:</p>
        <ul>
          <li>
            <code>NameNode</code> - 
            <a href="http://localhost:50070/">http://localhost:50070/</a>
          </li>
          <li>
            <code>JobTracker</code> - 
            <a href="http://localhost:50030/">http://localhost:50030/</a>
          </li>
        </ul>
        
        <p>
          Copy the input files into the distributed filesystem:<br/>
		  <code>$ bin/hadoop fs -put conf input</code>
		</p>
		
        <p>
          Run some of the examples provided:<br/>
          <code>
            $ bin/hadoop jar hadoop-*-examples.jar grep input output 'dfs[a-z.]+'
          </code>
        </p>
        
        <p>Examine the output files:</p>
        <p>
          Copy the output files from the distributed filesystem to the local 
          filesytem and examine them:<br/>
          <code>$ bin/hadoop fs -get output output</code><br/>
          <code>$ cat output/*</code>
        </p>
        <p> or </p>
        <p>
          View the output files on the distributed filesystem:<br/>
          <code>$ bin/hadoop fs -cat output/*</code>
        </p>

		<p>
		  When you're done, stop the daemons with:<br/>
		  <code>$ bin/stop-all.sh</code>
		</p>
      </section>
    </section>
    
    <section id="FullyDistributed">
      <title>Fully-Distributed Operation</title>
      
	  <p>For information on setting up fully-distributed, non-trivial clusters
	  see <a href="cluster_setup.html">Hadoop Cluster Setup</a>.</p>  
    </section>
    
    <p>
      <em>Java and JNI are trademarks or registered trademarks of 
      Sun Microsystems, Inc. in the United States and other countries.</em>
    </p>
    
  </body>
  
</document>
