2012-03-06 23:27:02 +00:00
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==================================
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Recovering from ceph-mon failure
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==================================
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2012-03-07 00:09:42 +00:00
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Any single ceph-mon failure should not take down the entire monitor
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cluster as long as a majority of the nodes are available. If that
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is the case--the remainin nodes are able to form a quorum--the ``ceph
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health`` command will report any problems::
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$ ceph health
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HEALTH_WARN 1 mons down, quorum 0,2
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and
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$ ceph health detail
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HEALTH_WARN 1 mons down, quorum 0,2
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mon.b (rank 1) addr 192.168.106.220:6790/0 is down (out of quorum)
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Generally speaking, simply restarting the affected node will repair things.
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If there are not enough monitors for form a quorum, the ``ceph``
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command will block trying to reach the cluster. In this situation,
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you need to get enough ``ceph-mon`` daemons running to form a quorum
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before doing anything else with the cluster.
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Replacing a monitor
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===================
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If, for some reason, a monitor data store becomes corrupt, the monitor
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can be recreated and allowed to rejoin the cluster, much like a normal
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monitor cluster expansion. See :ref:`adding-mon`.
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