[Linux-cluster] cmirror and RHEL 5

[Nikolas Lam]

On Mon, 2007-10-22 at 16:39 +0300, Mikko Partio wrote:
> Hello list
> 
> does RHEL 5 support cmirror (creating lvm mirrored volumes in a
> cluster environment)? I can't find any rpm packages for it. My goal is
> to increase redundancy by mirroring data between two sans. 
> 
> Regards
> 
> M

Hi Mikko,

Unfortunately the answer is no at the moment. This and LVM snapshots are
two things that I know can't be done with RHEL5's CLVM yet. I've been
told by Red Hat consultants that update 2 is the current target for
these features.

We wanted to use this solution to automate SAN failover between two HP
EVAs in different data centres but in the end have ended up having to
use HP's Continuous Access system to handle mirroring behind the scenes.
Fortunately we were already needed this mirroring elsewhere in the
university because I'm told the license costs six figures, which is a
lot more expensive than host based mirroring (0 dollars ;).

In some ways this is better because it removes a potential split brain
scenario that could happen if host-based mirroring was used. But it does
require manual intervention by a SAN administrator in the event of EVA
failure, which is not going to happen quickly if it happens, say at 3am.

Regards,

Nik