[Ocfs2-users] AoE ocfs2 local raid question

[Mark Fasheh]

On Wed, May 23, 2007 at 09:37:04AM +0200, Jaime Perea wrote:
> I have a small cluster (16 machines). An external machine is
> "exporting" a software raid-5 via the AoE protocol. The machines
> of the cluster mount the network device using ocfs2. In my case
> the network device is /dev/etherd/e11.1
> 
> My question is, can that external machine be also a member of
> the cluster? and if so, can it use its local /dev/md0 instead of the
> network device when mounting the ocfs2 filesystem?, This can be
> useful for backups and/or exporting the ocfs2 filesystem outside
> of the cluster.  

How are you exporting the storage? vblade?

I know that won't work with the iscsi target due to the block device and the
iscsi device having different caches. I suspect the same goes for any
in-kernel aoe target. It _might_ work with aoe if you're using a userspace
target that does direct io against the same md device though... I'd test it
pretty heavily 1st though (create files, on both nodes, put data in them,
make sure there's 100% coherence between nodes). In any case, if you must
mount on the target, I'd only do it long enough to make your backups - you
don't want the node exporting all your storage to fence :)

By the way, there's some slides available at
http://oss.oracle.com/projects/ocfs2/dist/documentation/cheap_clustering.pdf
regarding aoe/iscsi/ocfs2 that you might find useful.
	--Mark

--
Mark Fasheh
Senior Software Developer, Oracle
mark.fasheh at oracle.com