[Lustre-discuss] MDS Fail-Over planning.

Thomas Roth t.roth at gsi.de
Wed May 7 01:55:22 PDT 2008


Hi,

we are testing a similar setup, a HA-pair of servers for MGS/MDS, were 
the HA is provided by DRBD and Heartbeat.
So far we did not observe any problems. However, in the current 
'production' mode of our cluster, there hasn't been a HA-failover, so 
nothing could have gone wrong with that part of the setup.
In the test phase before, for instance once the power cables of the 
primary server were ripped out while someone was writing with iozone to 
the filesystem: nothing happened. These were large-file-writes, however. 
Writing, say, 5MB files, you certainly would notice the short 
disappearance of the MDT as a short interruption.
But no problems with inconsistencies between the two DRBD-MDT-partitions.

Now, if you plan to do that on the OSSs, I have no experience with that, 
but there is bug 15710, as mentioned by Brian, which is also positive 
about the use or DRBD.

Regards,
Thomas

Brock Palen wrote:
> I know some users talked about DRBD for the shared disk on the MDS.
> 
> What was the conclusion of this?  Bad Idea?  I do some high available  
> NFS using this exact same setup.
> 
> 
> DRBD  provides shared storage,
> Heart Beat is used to monitor hosts.
> IPMI  is used by HeartBeat to power down hosts that are to be killed.
> 
> The plan on our table right now is two thumpers as the OSS's.
> Then two x4100 or 4200/s  with mirrors SAS drives then shared across  
> with DRBD with Heart Beat.
> 
> 
> Any comments?  Any issues to be aware of?  Anyone running something  
> similar?
> 
> 
> Brock Palen
> www.umich.edu/~brockp
> Center for Advanced Computing
> brockp at umich.edu
> (734)936-1985
> 
> 
> 
> _______________________________________________
> Lustre-discuss mailing list
> Lustre-discuss at lists.lustre.org
> http://lists.lustre.org/mailman/listinfo/lustre-discuss

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