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RE: [Xen-users] Xen-DRBD Migration question

To: "John Madden" <jmadden@xxxxxxxxxxx>, "Eric Laflamme" <elaflamme@xxxxxxxx>
Subject: RE: [Xen-users] Xen-DRBD Migration question
From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
Date: Wed, 11 Aug 2010 09:40:07 +1000
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Thread-topic: [Xen-users] Xen-DRBD Migration question
> > I've heard from a post somewhere that a migration Secondary-Primary
can be
> done. Our best way to do this will be to put de VM on pause. Put the
drbd disk
> on Secondary. Then migrate the vm to the second host, then put the
drbd disk
> on second host to primary and unpause the vm. I've searched on google
and I
> can't find anything on this method.
> >
> > Is there a way to do this? Is there another way you are thinking of?
> What about a drbd device per vm, both set active/active?  Migration
> already ensures that only one vm at a time can write to the underlying
> device through its pause/unpause mechanics.

I can't speak for the OP but one of the attractions about
primary/secondary drbd for me is that you can't accidentally start the
vm on two nodes at once, ever. It would be nice to have the migration
handle the volume state transition automatically as I don't think there
is ever actually a need to have the drbd volume writeable on both nodes
at once, although a drbd volume isn't even open-able unless it's in the
primary state.


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