[Linux-cluster] Cluster behavior

[Lon Hohberger]

On Mon, 2009-08-17 at 16:59 -0500, Paras pradhan wrote:
> I have a 3 nodes cluster.
> 
> Node A - Vote 1
> 
> Node B - Vote 1
> 
> Node C - Votes 2
> 
> Qdisk - Votes 3
> 
> 
> Altogether the cluster has 7 votes. The required min quorum to run the
> cluster would be in this case 4. Now if I poweroff node 1, I can see
> Quorum Dissolved in the terminals of Node 2 and Node3 . This cluster
> has xen virtual machines.

I assume node 1 == node A, node 2 == node B, node 3 == node C.


> Whats wrong and how to do debug the problem?

Do they all "See" each other before you power off node 1 (where 1 ==
A) ?  Apart from having a node with 2 votes, the rest of the concept is
pretty similar to qdiskd's design for "all-but-1 die" case.

Expected behavior is that any of the following constitutes a quorate
cluster:

A+Qdisk      (4 votes)
B+Qdisk      (4 votes)
C+Qdisk      (4 votes)
A+B+Qdisk    (5 votes)
A+B+C        (4 votes)
A+B+C+Qdisk  (7 votes)

Effectively, you want to look at 'cman_tool status'.  Before losing a
node, you need to verify that each sees 7 votes.

-- Lon