[Info-vax] set cluster/expected_votes

Malcolm Dunnett nothome at spammers.are.scum
Tue Aug 11 22:59:12 EDT 2009


JF Mezei wrote:
> Malcolm Dunnett wrote:
> 
>>   What it does is tells the other nodes to recompute quorum based on the
>> votes remaining in the cluster. I don't know if you consider this "much" 
>> or not, but it would seem to be precisely what is needed in this situation.
> 
> It won't magically allow a cluster to continue to operate with fewer
> nodes than it had been designed to operate. AKA: you cannot cheat the
> minimums set by the sysgen expected_votes if I remember correctly.
>

    Of course it will (well not magically - it's by design). There is no 
"number of nodes the cluster has been designated to operate with" - it's 
a dynamic value based the nodes in the cluster. The required number of 
votes is always adjusted upwards as needed when a node joins the cluster 
- downward adjustments are not automatic - that's what REMOVE NODE is for.

   Are you perhaps thinking of the SYSGEN parameter EXPECTED_VOTES? This 
parameter is only significant during boot time - a node will not boot if 
it can't join a cluster with EXPECTED_VOTES votes. Once a node is 
running the SYSGEN parameter has no effect.

    Can you elaborate on the situation in which this won't work?

    I've used it to take a 5 vote (2+2+1) cluster down to 1 vote with no 
problem. From reading the description I can't see where it could be a 
problem - quorum is adjusted to reflect the number of votes remaining in 
the cluster.



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