[Pacemaker] Lustre and Multiple Mount Protection

[Bernd Schubert]

On Wednesday 23 December 2009, Dejan Muhamedagic wrote:
> Hi,
> 
> On Tue, Dec 22, 2009 at 06:52:34PM +0100, Michael Schwartzkopff wrote:
> > Hi,
> >
> > The Lustre Filesystem uses a feature called Multiple Mount Protection to
> > make sure that one device is really only mounted by one node.
> >
> > My question now: Is this feature really needed in a pacemaker cluster?
> >
> > In a pacemaker cluster with correctly enables STONITH the cluster manager
> > takes care that the resource is only mounted on one node, isn't it? At
> > least in my understanding it should. Only after getting the positive
> > feedback that the resource was stopped on the other node or the other
> > node was fenced pacemaker starts the resource on the second node, or?
> 
> Right. But I guess you knew that.

The problem are those annoying bugs that tell you the device is umounted 
although it is not. My lustre server agent, which I will submit here once I 
find some time to review it again, will protect you from this. I least I hope 
I did catch all Lustre bugs...
And then pacemaker does not protect you to mount a filesystem, for which 
presently e2fsck is running.



Cheers,
Bernd

-- 
Bernd Schubert
DataDirect Networks