[DRBD-user] DRBD with KVM for live migrations

Bart Coninckx bart.coninckx at telenet.be
Sun Oct 30 21:24:33 CET 2011

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On 10/30/11 21:18, Trey Dockendorf wrote:
> I do need live migration but not as a failover.  So the migration will
> be manual and not automatic.  In that case I would at some point have to
> run in primary/primary.  Is the cluster fs only for shared storage
> configurations?  Also what ensures that the VMs disk is only being
> accesses by one hypervisor node at a time?  Would libvirt or drbd
> controll/ensurs that or is it up to me?  Thats my main concern once I
> know this is feasible and the best route.
> Thanks
> - Trey

OK, I see now. Regardless, you need prim/prim then. The shared storage 
IS the DRBD resource. You need it to be the same on both nodes to be 
able to live migrate or even fail over. You could however also use DRBD 
to serve as shared storage for the config files. It makes sense to have 
this information the same on both nodes.
Ensuring unique access is established by, as mentioned, cluster 
software. The KVM resource (in case of Pacemaker) will have to be 
configured to be able to run uniquely on ONE node.


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