[ClusterLabs] Antw: Re: Antw: Re: Resources not monitored in SLES11 SP4 (1.1.12-f47ea56)

[Ulrich Windl]

>>> Ken Gaillot <kgaillot at redhat.com> schrieb am 27.06.2018 um 16:18 in Nachricht
<1530109097.6452.1.camel at redhat.com>:
> On Wed, 2018-06-27 at 07:41 +0200, Ulrich Windl wrote:
>> > > > Ken Gaillot <kgaillot at redhat.com> schrieb am 26.06.2018 um
>> > > > 18:22 in Nachricht
>> 
>> <1530030128.5202.5.camel at redhat.com>:
>> > On Tue, 2018-06-26 at 10:45 +0300, Vladislav Bogdanov wrote:
>> > > 26.06.2018 09:14, Ulrich Windl wrote:
>> > > > Hi!
>> > > > 
>> > > > We just observed some strange effect we cannot explain in SLES
>> > > > 11
>> > > > SP4 (pacemaker 1.1.12-f47ea56):
>> > > > We run about a dozen of Xen PVMs on a three-node cluster (plus
>> > > > some
>> > > > infrastructure and monitoring stuff). It worked all well so
>> > > > far,
>> > > > and there was no significant change recently.
>> > > > However when a colleague stopped on VM for maintenance via
>> > > > cluster
>> > > > command, the cluster did not notice when the PVM actually was
>> > > > running again (it had been started not using the cluster (a bad
>> > > > idea, I know)).
>> > > 
>> > > To be on a safe side in such cases you'd probably want to enable 
>> > > additional monitor for a "Stopped" role. Default one covers only 
>> > > "Started" role. The same thing as for multistate resources, where
>> > > you 
>> > > need several monitor ops, for "Started/Slave" and "Master" roles.
>> > > But, this will increase a load.
>> > > And, I believe cluster should reprobe a resource on all nodes
>> > > once
>> > > you 
>> > > change target-role back to "Started".
>> > 
>> > Which raises the question, how did you stop the VM initially?
>> 
>> I thought "(...) stopped one VM for maintenance via cluster command"
>> is obvious. It was something like "crm resource stop ...".
>> 
>> > 
>> > If you stopped it by setting target-role to Stopped, likely the
>> > cluster
>> > still thinks it's stopped, and you need to set it to Started again.
>> > If
>> > instead you set maintenance mode or unmanaged the resource, then
>> > stopped the VM manually, then most likely it's still in that mode
>> > and
>> > needs to be taken out of it.
>> 
>> The point was when the command to start the resource was given, the
>> cluster had completely ignored the fact that it was running already
>> and started to start the VM on a second node (which may be
>> desastrous). But that's leading away from the main question...
> 
> Ah, this is expected behavior when you start a resource manually, and
> there are no monitors with target-role=Stopped. If the node where you
> manually started the VM isn't the same node the cluster happens to
> choose, then you can get multiple active instances.
> 
> By default, the cluster assumes that where a probe found a resource to
> be not running, that resource will stay not running unless started by
> the cluster. (It will re-probe if the node goes away and comes back.)

But didn't this behavior change? I tohought it was different maybe a year ago or so.

> 
> If you wish to guard against resources being started outside cluster
> control, configure a recurring monitor with target-role=Stopped, and
> the cluster will run that on all nodes where it thinks the resource is
> not supposed to be running. Of course since it has to poll at
> intervals, it can take up to that much time to detect a manually
> started instance.

Did monitor roles exist always, or were those added some time ago?

> 
>> > > > Examining the logs, it seems that the recheck timer popped
>> > > > periodically, but no monitor action was run for the VM (the
>> > > > action
>> > > > is configured to run every 10 minutes).
> 
> Recurring monitors are only recorded in the log if their return value
> changed. If there are 10 successful monitors in a row and then a
> failure, only the first success and the failure are logged.

OK, din't know that.


Thanks a lot for the explanations!

Regards,
Ulrich
> 
>> > > > 
>> > > > Actually the only monitor operations found were:
>> > > > May 23 08:04:13
>> > > > Jun 13 08:13:03
>> > > > Jun 25 09:29:04
>> > > > Then a manual "reprobe" was done, and several monitor
>> > > > operations
>> > > > were run.
>> > > > Then again I see no more monitor actions in syslog.
>> > > > 
>> > > > What could be the reasons for this? Too many operations
>> > > > defined?
>> > > > 
>> > > > The other message I don't understand is like "<other-resource>:
>> > > > Rolling back scores from <vm-resource>"
>> > > > 
>> > > > Could it be a new bug introduced in pacemaker, or could it be
>> > > > some
>> > > > configuration problem (The status is completely clean however)?
>> > > > 
>> > > > According to the packet changelog, there was no change since
>> > > > Nov
>> > > > 2016...
>> > > > 
>> > > > Regards,
>> > > > Ulrich
> -- 
> Ken Gaillot <kgaillot at redhat.com>
> _______________________________________________
> Users mailing list: Users at clusterlabs.org 
> https://lists.clusterlabs.org/mailman/listinfo/users 
> 
> Project Home: http://www.clusterlabs.org 
> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf 
> Bugs: http://bugs.clusterlabs.org