[Beowulf] Lustre failover

[Bernd Schubert]

On Wednesday 10 September 2008 13:41:18 andrew holway wrote:
> >From the Lustre manual:-
>
> With OST servers it is possible to have a load-balanced active/active
> configuration.
> Each node is the primary node for a group of OSTs, and the failover
> node for other
> groups. To expand the simple two-node example, we add ost2 which is primary
> on nodeB, and is on the LUNs nodeB:/dev/sdc1 and nodeA:/dev/sdd1. This
> demonstrates that the /dev/ identity can differ between nodes, but both
> devices must map to the same physical LUN. In this type of failover
> configuration, you can
> mount two OSTs on two different nodes, and format them from either node.
> With failover, two OSSs provide the same service to the Lustre network in
> parallel. In case
> of disaster or a failure in one of the nodes, the other OSS can
> provide uninterrupted
> filesystem services.
> For an active/active configuration, mount one OST on one node and another
> OST on the other node. You can format them from either node.
>
> Anyone done this on a production system?

Yes, sure we do this all the time.

>
> Experiances? Comments?

You should use either careful manual failover or heartbeat + stonith to 
prevent accidental double mounts. Usually we have a setup like this:

http://www.pci.uni-heidelberg.de/tc/usr/bernd/downloads/lustre/MDS.jpg


Cheers,
Bernd

-- 
Bernd Schubert
Q-Leap Networks GmbH