[Pacemaker] Lustre and Multiple Mount Protection

[Dejan Muhamedagic]

Hi,

On Wed, Dec 23, 2009 at 05:50:57PM +0100, Bernd Schubert wrote:
> 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.

If the RA lies all bets are off, of course.

> 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.

I guess that the start action would fail in this case. Please
file a bugzilla if the RA does something unexpected.

Thanks,

Dejan

> 
> Cheers,
> Bernd
> 
> -- 
> Bernd Schubert
> DataDirect Networks