[ClusterLabs] set node in maintenance - stop corosync - node is fenced - is that correct ?

[Ken Gaillot]

On Mon, 2017-10-16 at 21:49 +0200, Lars Ellenberg wrote:
> On Mon, Oct 16, 2017 at 09:20:52PM +0200, Lentes, Bernd wrote:
> > ----- On Oct 16, 2017, at 7:38 PM, Digimer lists at alteeve.ca wrote:
> > > On 2017-10-16 01:24 PM, Lentes, Bernd wrote:
> > > > i have the following behavior: I put a node in maintenance
> > > > mode, afterwards stop
> > > > corosync on that node with /etc/init.d/openais stop.
> > > > This node is immediately fenced. Is that expected behavior ? I
> > > > thought putting a
> > > > node into maintenance does mean the cluster does not care
> > > > anymore about that
> > > > node.
> > OS is SLES 11 SP4. That's not the most recent one.
> > Pacmekaer is 1.1.12.
> > I didn't plan to remove the node, but to do some maintenance on it.
> > 
> > If i put the node in standby, then i can invoke
> > "/etc/init.d/openais
> > stop" without that node getting fenced.
> > But then all resources on that node are stopped/migrated. If i
> > don't
> > want that, i thought maintenance is the right way.
> > Am i wrong ?
> > 
> > Ah, i just saw that i wasn't complete clear. The node is fenced
> > after
> > stopping openais, not after putting it into maintenance.
> > I did that via "crm node maintenance <node>"
> 
> from the Changelog:
> 
> Changes since Pacemaker-1.1.15
>   ...
>   + pengine: do not fence a node in maintenance mode if it shuts down
> cleanly
>   ...
> 
> just saying ... may or may not be what you are seeing.
> 
> Short term "workaround" may be to do things differently.
> Maybe just set the cluster wide maintenance mode, not per node?

Sounds right.

Another thing to keep in mind is that even if pacemaker doesn't fence
the node, if you use DLM, DLM might fence the node (it doesn't know
about or respect any pacemaker maintenance/unmanaged settings).

I'd stop pacemaker before stopping corosync, in any case. In
maintenance mode, that should be fine. I don't think a running
pacemaker would be able to reconnect to corosync after corosync comes
back.

> What are you really trying to do,
> what is the reason you need it in maintenance-mode
> and stop pacemaker/corosync/openais/the clusterstack,
> but do not want to stop/migrate off the resources,
> as would be done with "standby"?
> 
-- 
Ken Gaillot <kgaillot at redhat.com>