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Re: [Linux-cluster] expected_votes meaning



You said that quorum is (expected_votes/2)+1 , which means 7/2=3.5+1= 4.5 ... is it rounded up or down?

2007/8/31, Patrick Caulfield <pcaulfie redhat com >:
Claudio Tassini wrote:
> Hi all,
>
> this could sound quite obvious but I really can't find a reference guide
> to cluster.conf parameters. What is the exact meaning of the
> expected_votes cman attribute ?  Is it the total number of votes on
> which cman calculates the quorum needing of a member or is it the actual
> number of votes needed by a member to boot?

expected_votes is the total number of votes in a fully functional cluster.
Quorum is calculated from this as (half the number of expected_votes)+1. when
the cluster has fewer than quorum votes then services will stall.


> I'll try to explain: 4-nodes cluster. 1 vote per node. 1 quorum disk
> with 3 votes. expected_votes set to 7 as read in the cluster faq. The
> faq says that every single node should be able to remain in the cluster
> as long as it can reach the quorum, with a total vote count of 4 (3 for
> the quorum, 1 for the node itself), which is claimed to be enough with
> an expected_votes of 7. This is why I'm quite confused... if
> expected_votes is 7, doesn't this mean that the "1 node+qdisk" vote
> count should be 7 to prevent quorum being dissolved?

So, in your system expected_votes is 7, quorum is 4. so any 1 node + the quorum
disk will be a valid cluster. Which sounds sensible :)

Patrick

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Claudio Tassini
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