Synnefo » snf-ganeti

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  <!ENTITY dhdate      "<date>June 20, 2007</date>">

  <!-- SECTION should be 1-8, maybe w/ subsection other parameters are

       allowed: see man(7), man(1). -->

  <!ENTITY dhsection   "<manvolnum>8</manvolnum>">

  <!ENTITY dhucpackage "<refentrytitle>ganeti-watcher</refentrytitle>">

  <!ENTITY dhpackage   "ganeti-watcher">

  <!ENTITY debian      "<productname>Debian</productname>">

  <!ENTITY gnu         "<acronym>GNU</acronym>">

  <!ENTITY gpl         "&gnu; <acronym>GPL</acronym>">

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<refentry>

  <refentryinfo>

    <copyright>

      <year>2007</year>

      <holder>Google Inc.</holder>

    </copyright>

    &dhdate;

  </refentryinfo>

  <refmeta>

    &dhucpackage;

    &dhsection;

    <refmiscinfo>ganeti 1.2</refmiscinfo>

  </refmeta>

  <refnamediv>

    <refname>&dhpackage;</refname>

    <refpurpose>ganeti cluster watcher</refpurpose>

  </refnamediv>

  <refsynopsisdiv>

    <cmdsynopsis>

      <command>&dhpackage; </command>

    </cmdsynopsis>

  </refsynopsisdiv>

  <refsect1>

    <title>DESCRIPTION</title>

    <para>

      The <command>&dhpackage;</command> is a periodically run script

      which is responsible for keeping the instances in the correct

      status.

    </para>

    <para>

      Its function is to try to keep running all instances which are

      marked as <emphasis>up</emphasis> in the configuration file, by

      trying to start them a limited number of times.

    </para>

    <para>In order to prevent piling up commands, all the

    <emphasis>gnt-*</emphasis> commands executed by ganeti-watcher are

    run with a timeout of 15 seconds.

    </para>

    <para>

      The command has a state file located at

      <filename>/var/lib/ganeti/restart_state</filename> and a log

      file at

      <filename>/var/log/ganeti/watcher.log</filename>. Removal of

      either file will not affect correct operation; the removal of

      the state file will just cause the restart counters for the

      instances to reset to zero.

    </para>

  </refsect1>

  <refsect1>

    <title>KNOWN BUGS</title>

    <para>

      Due to the way we initialize DRBD peers, restarting a secondary

      node for an instance will cause the DRBD endpoints on that node

      to disappear, thus all instances which have that node as a

      secondary will lose redundancy. The watcher does not detect this

      situation. The workaround is to manually run

      <command>gnt-instance activate-disks</command> for all the

      affected instances.

    </para>

  </refsect1>

  &footer;

</refentry>

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