[ClusterLabs] HALVM problem with 2 nodes cluster

Ferenc Wágner wferi at niif.hu
Wed Jan 18 14:56:03 EST 2017

Marco Marino <marino.mrc at gmail.com> writes:

> Ferenc, regarding the flag use_lvmetad in
> /usr/lib/ocf/resource.d/heartbeat/LVM I read:
>> lvmetad is a daemon that caches lvm metadata to improve the
>> performance of LVM commands. This daemon should never be used when
>> volume groups exist that are being managed by the cluster. The
>> lvmetad daemon introduces a response lag, where certain LVM commands
>> look like they have completed (like vg activation) when in fact the
>> command is still in progress by the lvmetad.  This can cause
>> reliability issues when managing volume groups in the cluster.  For
>> Example, if you have a volume group that is a dependency for another
>> application, it is possible the cluster will think the volume group
>> is activated and attempt to start the application before volume group
>> is really accesible... lvmetad is bad.
> in the function LVM_validate_all()

Wow, if this is true, then this is serious breakage in LVM.  Thanks for
the pointer.  I think this should be brought up with the LVM developers.

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