Re: [RFC] quorum module configuration bits

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Hi,

13.01.2012 21:21, Fabio M. Di Nitto wrote:
[snip]
>> + expected_votes is removed and instead auto-calculated based upon
>> quorum_votes in the node list

Is it possible to dynamically keep track of "seen" nodes here and use
only that nodes for expected_votes calculations?

I even have a use-case for that:
I "run" cluster consisting of max 17 nodes with UDPU, so all nodes are
listed in config. Currently only 3 nodes are powered on, because I do
not have load which requires more yet (and power is expensive in
european datacenters). When load increases I'd just power on additional
nodes and quorum expectations are recalculated automagically.
I have that implemented with corosync + pacemaker right now. Pacemaker
keeps that list of nodes and does quorum calculations correctly. And I'm
absolutely happy with that. From what I see changes being discussed will
break my happiness.

It would also be great if I'm able to forcibly remove inactive node from
that "seen" list with just one command on *one* cluster node. Use case
for that is a human error when wrong node is powered on by mistake.

Best,
Vladislav

>> + votes is moved to the individual node list
> 
> I will only speak for quorum:
> 
> quorum itself doesn't need quorum_votes. It is optional (like David
> already mentioned). default to 1.
> 
> quorum doesn't care about nodeid in general. A list of nodeid makes
> auto-tie-breaker working a bit earlier in the first cluster bootstrap
> process, but it's nothing worth going crazy for.
> 
> Requiring a list is not mandatory either for quorum operations.
> 
> I suggest to keep it flexible instead.  Not everybody wants or need a
> nodelist (mcast/bcast).
> 
> I suggest that if nodelist is available quorum uses it by default.
> If the list is not available, then we want expected_votes.
> 
> If neither are available we error out, if both are available the list
> has higher priority vs expected_votes setting.
> 
> I personally have no opinion on how the list is structured as long as I
> can easily reiterate through the node list and be able to find out which
> node I am in that list (specially if nodeid are not specified).
> 
> Fabio
> _______________________________________________
> discuss mailing list
> discuss@xxxxxxxxxxxx
> http://lists.corosync.org/mailman/listinfo/discuss

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