[Lustre-discuss] Understanding of MMP

[Michael Schwartzkopff]

Hi,

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?

From the manuals I found the MMP time of 109 seconds? Is it correct that after 
the umount the next node cannot mount the same filesystem within 10 seconds?

So the solution would be to wait fotr 10 seconds mounting the resource on the 
next node. Is this correct?

Thanks.

-- 
Dr. Michael Schwartzkopff
MultiNET Services GmbH
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