[Openais] quorum service question
Dietmar Maurer
dietmar at proxmox.com
Tue Nov 17 02:59:16 PST 2009
> > But AFAIK this information is local (not copied to other nodes). And
> the votequorum seems to add new nodes dynamically. So how can I make
> sure that all nodes in the cluster use the same values? I guess it is
> important that all nodes start with the same value?
> >
> > Or is it better to not set expected_votes at start:
> >
> > quorum {
> > provider: corosync_votequorum
> > votes: 1
> > }
> >
> > And set expected_votes later with an application that has static
> knowledge about all cluster members?
>
> The quorum service really works best if you have a common configuration
> system so that the values are the same on all nodes.
The question is how to do that. Quorum setting are read from /etc/corosync/corosync.conf, but there is no way to write that file - the confdb interface is read-only?
> Having said that it should always use the highest expected_votes value,
> so as you add nodes (with, I hope, increasing values for
> expected_votes!) then the quorum requirement will increase. So although
> the actual values for expected_votes per node are not replicated, the
> effect is.
This does not work when the cluster is partitioned. If you start with low expected_votes settings both partitions can get quorate?
- Dietmar
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