[ClusterLabs] Antw: [EXT] Re: Updating quorum configuration without restarting cluster

[Ulrich Windl]

>>> Strahil Nikolov <hunter86_bg at yahoo.com> schrieb am 21.06.2021 um 13:08 in
Nachricht <135177996.1214287.1624273688420 at mail.yahoo.com>:
> 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.

Apply with some care: DLM/CPG-apps probably don't like that.

> 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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