ganeti-watcher.sgml

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  <!-- Fill in your name for FIRSTNAME and SURNAME. -->
  <!-- Please adjust the date whenever revising the manpage. -->
  <!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>@LOCALSTATEDIR@/lib/ganeti/restart_state</filename> and a log
      file at
      <filename>@LOCALSTATEDIR@/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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