[ClusterLabs] Updating quorum configuration without restarting cluster

[Strahil Nikolov]

Also, it's worth mentioning that you can still make changes without downtime.
For example you can edit corosync conf and push it to all nodes, then set global maintenance, stop the cluster and then start it again.
Best Regards,Strahil Nikolov

 
 
  On Mon, Jun 21, 2021 at 9:37, Jan Friesse<jfriesse at redhat.com> wrote:   Gerry,

> Dear community,
> 
> I would like to ask few questions regarding Corosync/Pacemaker quorum configuration.
> 
> When updating the Corosync's quorum configuration I added last_man_standing, and
> auto_tie_breaker in corosync.conf on all hosts and refreshed with
> 'corosync-cfgtool -R'.
> Note that that man page included with the rpm says that the -R option with "Tell
> all instances of corosync in this cluster to reload corosync.conf."
> 
> Next I run 'corosync-quorumtool -s', but it did not show the new quorum flags
> for auto tiebreaker and last man standing.
> 
> Once I restarted the corosync cluster, the auto tiebreaker flags and last man
> standing flags appeared in the corosync-quorumtool output as I expected.
> 
> So my questions are:
> 1. Does corosync-quorumtool actually shows the active quorum configuration? If
> not how can I query the active quorum config?

Yes, corosync-quorumtool shows quorum configuration which is really used 
(it's actually only source of truth, cmap is not).

> 
> 2. Is it possible to update the quorum configuration without restarting the cluster?

Partly.

Basically only quorum.two_node and quorum.expected_votes are changeable 
during runtime. Other options like:
- quorum.allow_downscale
- quorum.wait_for_all
- quorum.last_man_standing
- quorum.auto_tie_breaker
- quorum.auto_tie_breaker_node

are not (wait_for_all is a little bit more complicated - when not 
explicitly set/unset it follows two_node so it is possible, but only in 
this special case, to change it via changing two_node).

Regards,
  Honza

btw. I've already replied to Janghyuk Boo so mostly copying same answer 
also here.

> 
> Thank you,
> Gerry Sommerville
> E-mail: gerry at ca.ibm.com <mailto:gerry at ca.ibm.com>
> 
> 
> 
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