[Linux-HA] Cluster aware LVM.
alain.st-denis at ec.gc.ca
Mon Dec 17 12:58:52 MST 2007
I managed to configure Redhat's cman in order to use clvmd within our
heartbeat2 clusters which are attached to a shared SAN. While working on
this, I felt it was a bit redundant to use 2 cluster managers (cman and crm)
in the same cluster. Has there been any work done to have clvmd adapted to
crm? Would that be a lot of work?
I am considering using clvmd to gard our non-shared file systems living on a
shared SAN against accidental concurrent access. In order to achieve this, I
would have to modify the LVM RA to have it work at the logical volume level
instead of the volume group level. The idea would be to use exclusive locks
to guarantee only one node accesses a logical volume resource. This would
require that our volume groups be made cluster aware. This CLVM RA would
run "lvchange -a ey /some_lv" when starting a resource and would fail if the
lock can't be acquired.
I'd like your opinion: am I on the right track? Given properly configured
stonith resources, I haven't made up my mind if this is useful at all... It
(this CLVM RA) might be a good protection against human mistake since trying
to access a lv from another node would fail. A sysadmin could still activate
the lv since the lock is advisory, but it should give someone a hint.
If other methods to achieve the same goal already exist, please describe them
or show me where I can find any relevant docs.
Thanks and regards,
Supercomputing, Systems and Storage
Canadian Meteorological Centre
Meteorological Service of Canada
Tel: +1 514 421 4697
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