[Linux-cluster] Cluster behavior

[Paras pradhan]

On Wed, Aug 19, 2009 at 8:25 AM, Lon Hohberger<lhh at redhat.com> wrote:
> 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.

Yes before loosing a node.. its 7.. cman_tool status says its 7.

Here is the output when all the nodes are active.

On Node B or Node 2:

root at cvtst2 ~]# cman_tool status
Version: 6.1.0
Config Version: 54
Cluster Name: cvtst
Cluster Id: 3338
Cluster Member: Yes
Cluster Generation: 2068
Membership state: Cluster-Member
Nodes: 3
Expected votes: 6
Quorum device votes: 3
Total votes: 7
Quorum: 4
Active subsystems: 10
Flags: Dirty
Ports Bound: 0 11 177
Node name: cvtst2
Node ID: 1
Multicast addresses: x.x.x.x
Node addresses: x.x.x.172
[root at cvtst2 ~]#


Now Powered off node A or node 1.

Here is the output.

Version: 6.1.0
Config Version: 54
Cluster Name: cvtst
Cluster Id: 3338
Cluster Member: Yes
Cluster Generation: 2080
Membership state: Cluster-Member
Nodes: 2
Expected votes: 6
Total votes: 3
Quorum: 2
Active subsystems: 10
Flags: Dirty
Ports Bound: 0 11 177
Node name: cvtst1
Node ID: 2
Multicast addresses: x.x.x.x
Node addresses: x.x.x.172

I have noticed after poweroff the total votes turns to 3 ( for few
seconds), Then I see quoram dissolved . But afer few seconds the
cluster is back and I can see the total votes to 6. What  might be the
issue here.








>
> -- Lon
>
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Thanks!
Paras.