Hi Steve,
02.09.2011 20:30, Steven Dake wrote:
> On 09/02/2011 12:59 AM, Vladislav Bogdanov wrote:
...
>> I'm trying to further investigate problem I described at
>> https://www.redhat.com/archives/cluster-devel/2011-August/msg00133.html
>>
>> The main problem for me there is that pacemaker first sees transitional
>> membership with left nodes, then it sees stable membership with that
>> nodes returned back, and does nothing about that. On the other hand,
>> dlm_controld sees CPG_REASON_NODEDOWN events on CPGs related to all its
>> lockspaces (at the same time with transitional membership change) and
>> stops kernel part of each lockspace until whole cluster is rebooted (or
>> until some other recovery procedure which unfortunately does not happen
>
> I believe fenced should reboot the node, but only if there is quorum.
> It is possible your cluster has lost quorum during this series of
> events. I have copied Dave for his feedback on this point.
Aha. I think so too. But fenced doesn't do that as well as all other
daemons from cluster3, this part of code is identical among them, that's
why I think this does not depend on whether cman or pacemaker stack is used:
fence/fenced/cpg.c around line 1440 (as for 3.1.1)
if (left_list[i].reason == CPG_REASON_NODEDOWN ||
left_list[i].reason == CPG_REASON_PROCDOWN) {
memb->failed = 1;
cg->failed_count++;
}
...
if (left_list[i].reason == CPG_REASON_PROCDOWN)
kick_node_from_cluster(memb->nodeid);
probably last lines should be:
if (left_list[i].reason == CPG_REASON_NODEDOWN ||
left_list[i].reason == CPG_REASON_PROCDOWN)
kick_node_from_cluster(memb->nodeid);
at least in one of daemons (fenced is a good candidate, but I prefer
dlm_controld)?
About quorum: 3 node cluster was split to two partitions, 2 bare-metal
and 1 VM nodes.
When I found that, two metal ones were in 'kern_stop' state,
transitioning via 'kern_stop,fencing' state I suppose. VM did not have
quorum, so it was left in 'kern_stop,fencing' state.
dlm dump says:
1313579105 clvmd add_change cg 4 remove nodeid 1543767306 reason 3
That means CPG_REASON_NODEDOWN event.
Then:
1313579105 Node 1543767306/mgmt01 has not been shot yet
1313579105 clvmd check_fencing 1543767306 wait add 1313562825 fail
1313579105 last 0
1313579107 Node 1543767306/mgmt01 was last shot 'now'
This is not true, there is no line about actual fencing scheduling (and
it is clear from code why). This could be a deficiency of .pcmk
dlm_controld variant, but that is not important here I think.
1313579107 clvmd check_fencing 1543767306 done add 1313562825 fail
1313579105 last 1313579107
1313579107 clvmd check_fencing done
>
>> :( ). It neither requests to fence left node nor recovers when node is
>> returned on next stable membership.
>>
>> Could anyone please help me to understand, what is a correct CPG
>> behavior on membership change?
>> From what I see, CPG emits CPG_REASON_NODEDOWN event on both
>> transitional and stable membership if there is node which left the
>> cluster. Am I correct here? And is that a right thing if I am?
Ah, I should be mixed something, it was quite long ago. Actually, yes,
that was transitional one. There was only one such event.
>>
>
> Line #'s where this happens?
I just saw that in pacemaker plugin logs and in dlm_tool dump logs.
Their timestamps are identical.
>
>> If yes, is there a way do detect membership change type (transitional pr
>> stable) through CPG API?
>>
>
> A transitional membership will always contain a subset of the previous
> regular membership. This means it will always contains 0 or more left
> members. A transitional membership means "The membership of nodes
> transitioning from previous regular membership to new regular mebmership".
>
> A regular configuration is where members are added to the configuration
> when detected. A transitional membership never has nodes added to it.
Thank you for clarification very much.
Shouldn't pacemaker then schedule fencing itself (from the partition
with quorum) if there are left nodes? BTW, actually there was only
second or two between transitional and regular membership. I probably
need to ask Andrew for pacemaker logic details.
Unfortunately I lost that logs and hardly can reproduce that :(
That was a VM which left the cluster, and it probably just suffered from
insufficient host CPU time.
And... Just wandering, what could be a reason to recalculate membership
if there are 0 left or added members?
>
>> Hoping for answer,
>>
>
> It would be nice if cpg and totem had a direct relationship in how their
> transitional and regular configurations were generated, but this doesn't
> happen currently. I am not sure if there is a good reason for this.
Pacemaker uses totem? At least it doesn't use cpg. May be that is the
reason of not-fencing from within it?
Thank you very much,
Vladislav
_______________________________________________
Openais mailing list
Openais@lists.linux-foundation.org
https://lists.linux-foundation.org/mailman/listinfo/openais
