[Lustre-discuss] DRBD + active/active OST, again

[Johann Lombardi]

On Tue, Mar 02, 2010 at 02:01:06PM +0100, Andrew Godziuk wrote:
> Then I guess this part of manual should be changed:
>
> "The active/passive configuration is seldom used for OST servers as it
> doubles hardware costs without improving performance. On the other
> hand, an active/active cluster configuration can improve performance
> by serving and providing arbitrary failover protection to a number of
> OSTs."
>
> to state explicitly that active/active scenario is only possible when
> OSS is active for some OSTs and passive for some others.

Yes, i think this is explained in the next section:
"For OST failover, multiple OSS nodes are configured to be able to serve the
same OST. However, only one OSS node can serve the OST at a time. An OST can be
moved between OSS nodes that have access to the same storage device using
umount/mount commands. "

BTW, in your case, since you did not specify a failover node for the OST at
mkfs time, the lustre clients are not aware of the alternative path and thus
won't try to reach the OST through the 2nd OSS. So your filesystem should
still be safe since the 2nd mount instance should never receive any client
connection. However, I would still recommend to umount the OST on the 2nd
OSS asap.

Johann