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

[Ulrich Windl]

>>> Jan Friesse <jfriesse at redhat.com> schrieb am 21.06.2021 um 08:37 in
Nachricht
<8067590c-866d-85b4-0930-193047c1333c at redhat.com>:
> 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).

I wonder:
Could the command detect what's tried to be changed online, and then log a
warning for settings that cannot be changed?

...

Regards,
Ulrich