Red Hat Bugzilla – Bug 318361
cman needs to include qdisk votes in expected votes display
Last modified: 2009-04-16 18:51:43 EDT
Description of problem:
Three node cluster w/ qdisk of 2 nodes. Shouldn't expected votes be that same as
total votes in this case where all are members?
[root@taft-03 ~]# cman_tool status
Config Version: 11
Cluster Name: TAFTASTIC
Cluster Id: 39245
Cluster Member: Yes
Cluster Generation: 1108
Membership state: Cluster-Member
Expected votes: 3
Total votes: 5
Active subsystems: 9
Ports Bound: 0 11
Node name: taft-03.lab.msp.redhat.com
Node ID: 3
Multicast addresses: 18.104.22.168
Node addresses: 10.15.89.69
Version-Release number of selected component (if applicable):
The value in there is technically correct, but confusing I think.
Here's the quorum calculation from the source code (and the VMS cluster manual!)
q1 = (highest_expected + 2) / 2;
q2 = (total_votes + 2) / 2;
newquorum = max(q1, q2);
newquorum = max(oldquorum, newquorum);
highest_expected is the maximum value of expected_votes on all active nodes, and
total_votes is what you would expect: the total of all active votes in the system.
If you don't explicitly set expected_votes in cluster.conf then it is calculated
as the total votes contributed by REAL nodes (qdisk doesn't appear in
cluster.conf as a node)
So the confusion arises, I think, because qdisk isn't added to expected_votes at
"cman_tool join" time and because it contributes no expected_votes of its own
(it gets set to zero, and is therefore always ignored).
I can't see this being a blocker but we might like to think of ways to clarify
things in the future. Perhaps by getting the join process to look at the qdisk
keys in ccs and add those votes to expected_votes.
The more I think about this, the less happy I am fudging expected_votes with the
quorum disk votes. I think perhaps the thing to do is to display the quorum disk
votes in 'cman_tool status' immediately after 'Expected votes'. I think that
should be clear enough.
Created attachment 278351 [details]
Checked into HEAD. here's the patch for RHEL5, as I don't think this has been
approved for 5.2
Created attachment 294359 [details]
This is a slightly nicer patch and matches what is in HEAD of CVS.
Added to RHEL5 branch:
Author: Christine Caulfield <email@example.com>
Date: Mon Apr 28 16:10:09 2008 +0100
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An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
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