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<refentry id="ctdb_mutex_ceph_rados_helper.7">

  <refmeta>
    <refentrytitle>Ceph RADOS Mutex</refentrytitle>
    <manvolnum>7</manvolnum>
    <refmiscinfo class="source">ctdb</refmiscinfo>
    <refmiscinfo class="manual">CTDB - clustered TDB database</refmiscinfo>
  </refmeta>

  <refnamediv>
    <refname>ctdb_mutex_ceph_rados_helper</refname>
    <refpurpose>Ceph RADOS cluster mutex helper</refpurpose>
  </refnamediv>

  <refsect1>
    <title>DESCRIPTION</title>
    <para>
      ctdb_mutex_ceph_rados_helper can be used as a recovery lock provider
      for CTDB.  When configured, split brain avoidance during CTDB recovery
      will be handled using locks against an object located in a Ceph RADOS
      pool.
      To enable this functionality, include the following line in the
      <literal>[cluster]</literal> section of
      <citerefentry><refentrytitle>ctdb.conf</refentrytitle>
      <manvolnum>5</manvolnum></citerefentry>:
    </para>
    <screen format="linespecific">
recovery lock = !ctdb_mutex_ceph_rados_helper [Cluster] [User] [Pool] [Object]

Cluster: Ceph cluster name (e.g. ceph)
User: Ceph cluster user name (e.g. client.admin)
Pool: Ceph RADOS pool name
Object: Ceph RADOS object name
    </screen>
    <para>
      The Ceph cluster <parameter>Cluster</parameter> must be up and running,
      with a configuration, and keyring file for <parameter>User</parameter>
      located in a librados default search path (e.g. /etc/ceph/).
      <parameter>Pool</parameter> must already exist.
    </para>
    <para>
      For informational purposes, ctdb_mutex_ceph_rados_helper will also
      register the recovery lock holder in Ceph Manager's service map.
    </para>
  </refsect1>

  <refsect1>
    <title>SEE ALSO</title>
    <para>
      <citerefentry><refentrytitle>ctdb</refentrytitle>
      <manvolnum>7</manvolnum></citerefentry>,

      <citerefentry><refentrytitle>ctdbd</refentrytitle>
      <manvolnum>1</manvolnum></citerefentry>,

      <ulink url="http://ctdb.samba.org/"/>
    </para>
  </refsect1>

  <refentryinfo>
    <author>
      <contrib>
	This documentation was written by David Disseldorp
      </contrib>
    </author>

    <copyright>
      <year>2016</year>
      <holder>David Disseldorp</holder>
    </copyright>
    <legalnotice>
      <para>
	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License as
	published by the Free Software Foundation; either version 3 of
	the License, or (at your option) any later version.
      </para>
      <para>
	This program is distributed in the hope that it will be
	useful, but WITHOUT ANY WARRANTY; without even the implied
	warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
	PURPOSE.  See the GNU General Public License for more details.
      </para>
      <para>
	You should have received a copy of the GNU General Public
	License along with this program; if not, see
	<ulink url="http://www.gnu.org/licenses"/>.
      </para>
    </legalnotice>
  </refentryinfo>

</refentry>
