[Ocfs2-users] OCFS2 and Snapshots

[Michael Wood]

Andre Brinkmann <brinkman at hni.upb.de> wrote:
> I am trying to couple OCFS2 with a storage virtualization
> environment to use features like mirroring and snapshots.
> Unfortunately it seems to be impossible for ocfs2console (and
> for mount.ocfs2) to distinguish between the original volume
> and its snapshot and ocffs2 stops the mount-process with the
> following messages:
[snip]
> Is it possible too change the uuid and other relevant
> parameters?

On Thu, Jul 20, 2006 at 09:29:29AM -0700, Alexei_Roudnev replied:
> Are you sure, that your snapshort/mirroring software can work
> on the cluster (shared disks)? I do not know such tools,
> except parts of Poliserver file system and (possible, with
> serious limitation) Veritas Volume Manager.

I am sure he means that he is using something like an HP EVA or
IBM DS4000 etc. that can do a snapshot of a LUN.  This looks
like a block for block copy of the original LUN, so if you try
to mount it, the UUIDs etc. will be identical and OCFS2 will
complain.

i.e. the snapshot "software" is built into the Storage array and
does not need to be aware of any clustering.  It just copies (or
copies on write) the data to another area of disk which can be
made available to the original machine(s) or to other machines
entirely.

-- 
Michael Wood <mwood at icts.uct.ac.za>