impala/docs/topics/impala_processes.xml

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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="processes">

  <title>Starting Impala</title>
  <prolog>
    <metadata>
      <data name="Category" value="Starting and Stopping"/>
      <data name="Category" value="Impala"/>
      <data name="Category" value="Administrators"/>
      <data name="Category" value="Operators"/>
    </metadata>
  </prolog>

  <conbody>

    <p rev="1.2">
      <indexterm audience="Cloudera">state store</indexterm>
      <indexterm audience="Cloudera">starting services</indexterm>
      <indexterm audience="Cloudera">services</indexterm>
      To activate Impala if it is installed but not yet started:
    </p>

    <ol>
      <li>
        Set any necessary configuration options for the Impala services. See
        <xref href="impala_config_options.xml#config_options"/> for details.
      </li>

      <li>
        Start one instance of the Impala statestore. The statestore helps Impala to distribute work efficiently,
        and to continue running in the event of availability problems for other Impala nodes. If the statestore
        becomes unavailable, Impala continues to function.
      </li>

      <li>
        Start one instance of the Impala catalog service.
      </li>

      <li>
        Start the main Impala service on one or more DataNodes, ideally on all DataNodes to maximize local
        processing and avoid network traffic due to remote reads.
      </li>
    </ol>

    <p>
      Once Impala is running, you can conduct interactive experiments using the instructions in
      <xref href="impala_tutorial.xml#tutorial"/> and try <xref href="impala_impala_shell.xml#impala_shell"/>.
    </p>

    <p outputclass="toc inpage"/>
  </conbody>

  <concept id="starting_via_cm">

    <title>Starting Impala through Cloudera Manager</title>

    <conbody>

      <p>
        If you installed Impala with Cloudera Manager, use Cloudera Manager to start and stop services. The
        Cloudera Manager GUI is a convenient way to check that all services are running, to set configuration
        options using form fields in a browser, and to spot potential issues such as low disk space before they
        become serious. Cloudera Manager automatically starts all the Impala-related services as a group, in the
        correct order. See
        <xref href="http://www.cloudera.com/documentation/enterprise/latest/topics/cm_mc_start_stop_service.html" scope="external" format="html">the
        Cloudera Manager Documentation</xref> for details.
      </p>

      <note>
        <p conref="../shared/impala_common.xml#common/udf_persistence_restriction"/>
      </note>
    </conbody>
  </concept>

  <concept id="starting_via_cmdline">

    <title>Starting Impala from the Command Line</title>

    <conbody>

      <p>
        To start the Impala state store and Impala from the command line or a script, you can either use the
        <cmdname>service</cmdname> command or you can start the daemons directly through the
        <cmdname>impalad</cmdname>, <codeph>statestored</codeph>, and <cmdname>catalogd</cmdname> executables.
      </p>

      <p>
        Start the Impala statestore and then start <codeph>impalad</codeph> instances. You can modify the values
        the service initialization scripts use when starting the statestore and Impala by editing
        <codeph>/etc/default/impala</codeph>.
      </p>

      <p>
        Start the statestore service using a command similar to the following:
      </p>

      <p>
<codeblock>$ sudo service impala-state-store start</codeblock>
      </p>

      <p rev="1.2">
        Start the catalog service using a command similar to the following:
      </p>

<codeblock rev="1.2">$ sudo service impala-catalog start</codeblock>

      <p>
        Start the Impala service on each DataNode using a command similar to the following:
      </p>

      <p>
<codeblock>$ sudo service impala-server start</codeblock>
      </p>

      <note>
        <p conref="../shared/impala_common.xml#common/udf_persistence_restriction"/>
      </note>

      <p>
        If any of the services fail to start, review:
        <ul>
          <li>
            <xref href="impala_logging.xml#logs_debug"/>
          </li>

          <li>
            <xref href="impala_troubleshooting.xml#troubleshooting"/>
          </li>
        </ul>
      </p>
    </conbody>
  </concept>
</concept>