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Re: [Linux-cluster] RH Cluster doesn't pass basic acceptance tests -bug in fenced?



On Thu, 2007-01-11 at 00:54 -0600, Jayson Vantuyl wrote:

> That said, I think the solution is actually to set up the qdisk to
> have a vote *AND* not configure the system as a two-node cluster. 
>  Basically, take off the two-node flag for CMAN, set CMAN's
> expected_votes to 2, give each node 1 vote and the qdisk 1 vote.

That's correct, if you're using a single heuristic to implement a
tiebreaker.

> That way, two running nodes give you quorum, either node + qdisk gives
> you quorum, and either node - qdisk is inquorate.

With a multi-point qdisk setup, you want qdisk to be required
(generally) - i.e., when monitoring multiple network paths.  However,
for a 2-node + tiebreaker setup, yours looks right.

> Can any of the cluster gods comment on this?  I usually have 3 or more
> nodes.

I hadn't considered the implications of doing 1 vote for 3+ node
clusters, but I don't think there are any; it should work, but it
wouldn't be particularly useful.

The man pages talk about the general setup for making N->1 failure
recovery work using qdisk, but it's missing the 2-node+tiebreaker case.
I'll have to add that (since it's a *very* interesting use case).

-- Lon



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