[Lustre-discuss] Understanding of MMP

[Michael Schwartzkopff]

Am Montag, 19. Oktober 2009 20:42:19 schrieben Sie:
> On Monday 19 October 2009, Andreas Dilger wrote:
> > On 19-Oct-09, at 08:46, Michael Schwartzkopff wrote:
> > > perhaps I have a problem understanding multiple mount protection
> > > MMP. I have a
> > > cluster. When a failover happens sometimes I get the log entry:
> > >
> > > Oct 19 15:16:08 sososd7 kernel: LDISKFS-fs warning (device dm-2):
> > > ldiskfs_multi_mount_protect: Device is already active on another node.
> > > Oct 19 15:16:08 sososd7 kernel: LDISKFS-fs warning (device dm-2):
> > > ldiskfs_multi_mount_protect: MMP failure info: last update time:
> > > 1255958168,
> > > last update node: sososd3, last update device: dm-2
> > >
> > > Does the second line mean that my node (sososd7) tried to mount /dev/
> > > dm-2 but
> > > MMP prevented it from doing so because the last update from the old
> > > node
> > > (sososd3) was too recent?
> >
> > The update time stored in the MMP block is purely for informational
> > purposes.  It actually uses a sequence counter that has nothing to do
> > with the system clock on either of the nodes (since they may not be in
> > sync).
> >
> > What that message actually means is that sososd7 tried to mount the
> > filesystem on dm-2 (which likely has another "LVM" name that the kernel
> > doesn't know anything about) but the MMP block on the disk was modified
> > by sososd3 AFTER sososd7 first looked at it.
>
> Probably, bug#19566. Michael, which Lustre version do you exactly use?
>
>
> Thanks,
> Bernd

I got version 1.8.1.1 which was published last week. Is the fix included or 
only in 1.8.2?

Greetings,
-- 
Dr. Michael Schwartzkopff
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