[CentOS] Clustering MySQL
J Potter
jpotter-centos at codepuppy.com
Wed Dec 12 14:50:44 UTC 2007
> After all the discussions regarding MySQL-style clustering (multi-
> master etc), what about a "classic" HA cluster for MySQL? Since the
> OP mentioned high availability, wouldn't the simplest solution be
> failover clustering (ie. single master with failover, shared
> storage, fenced nodes etc) via Centos CS?
We have this running in one setup, and it's been working (mostly) fine:
- master-master setup
- heartbeat creating a virtual IP
- all mysql clients use the virtual IP
So, effectively, it's a master-master setup where only 1 master is
ever receiving traffic, and if that master fails, it'll automatically
fail-over to the standby master.
The benefit of doing master-master in this scenario is that there's no
real recovery process needed for restoring redundancy -- when the
failed master comes back online, it catches up with the current
master. (Make sure auto-fallback is off in heartbeat.)
The only problem I've seen is that a crashed node may not be able to
replicate correctly, if its on-disk log position gets out of sync with
what the other node has. It seems if this happens one has to do a real
sync (lock tables, lvm snapshot, unlock tables, if you're willing to
give up the storage needed for the lvm snapshot; or rsync, shutdown
and re-rsync, startup).
best,
Jeff
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