Revision 6328fea3 man/ganeti-watcher.sgml

b/man/ganeti-watcher.sgml
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    <para>
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      The <command>&dhpackage;</command> is a periodically run script
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      which is responsible for keeping the instances in the correct
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      status.
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      status. It has two separate functions, one for the master node
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      and another one that runs on every node.
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    </para>
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    <para>
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      Its primary function is to try to keep running all instances
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      which are marked as <emphasis>up</emphasis> in the configuration
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      file, by trying to start them a limited number of times.
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    </para>
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    <refsect2>
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      <title>Master operations</title>
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    <para>
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      Its other function is to <quote>repair</quote> DRBD links by
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      reactivating the block devices of instances which have
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      secondaries on nodes that have been rebooted.
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    </para>
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      <para>
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        Its primary function is to try to keep running all instances
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        which are marked as <emphasis>up</emphasis> in the configuration
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        file, by trying to start them a limited number of times.
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      </para>
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    <para>
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      The watcher does synchronous queries but will submit jobs for
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      executing the changes. Due to locking, it could be that the jobs
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      execute much later than the watcher executes them.
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    </para>
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      <para>
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        Its other function is to <quote>repair</quote> DRBD links by
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        reactivating the block devices of instances which have
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        secondaries on nodes that have been rebooted.
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      </para>
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    </refsect2>
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    <refsect2>
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      <title>Node operations</title>
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      <para>
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        The watcher will restart any down daemons that are appropriate
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        for the current node.
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      </para>
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      <para>
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        In addition, it will execute any scripts which exist under the
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        <quote>watcher</quote> directory in the ganeti hooks directory
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        (@SYSCONFDIR@/ganeti/hooks). This should be used for
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        lightweight actions, like starting any extra daemons.
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      </para>
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      <para>
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        If the cluster
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        parameter <literal>maintain_node_health</literal> is enabled,
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        then the watcher will also shutdown instances and DRBD devices
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        if the node is declared as offline by known master candidates.
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      </para>
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      <para>
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        The watcher does synchronous queries but will submit jobs for
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        executing the changes. Due to locking, it could be that the jobs
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        execute much later than the watcher executes them.
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      </para>
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    </refsect2>
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  </refsect1>
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  <refsect1>
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    <title>FILES</title>
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    <para>
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      The command has a state file located at
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      <filename>@LOCALSTATEDIR@/lib/ganeti/watcher.data</filename> and a log
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      file at
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      <filename>@LOCALSTATEDIR@/lib/ganeti/watcher.data</filename>
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      (only used on the master) and a log file at
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      <filename>@LOCALSTATEDIR@/log/ganeti/watcher.log</filename>. Removal of
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      either file will not affect correct operation; the removal of
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      the state file will just cause the restart counters for the

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