[DRBD-user] DRBD primary/primary for KVM - what is the best option?

[Ben Timby]

Michael, sorry I did not speak about KVM, I have never used it, my
experience is with Xen, so I can only assume you can do something
similar with KVM. My point was that having a dedicated DRBD resource
for each VM (as opposed to replicating the entire volume) gives you
granular control over each virtual disk. Allowing you to move a VM
from one machine to the other, and not requiring that you have a
primary/primary setup and a cluster file system. This is of course at
the expense of having many LVs and DRBD resources, but I have not run
into any issues with my setup so far.

On Mon, May 10, 2010 at 2:29 PM, Ben Timby <btimby at gmail.com> wrote:
> Michael, I have a similar setup, however, I am going with a simpler
> configuration.
>
> I have two Xen hypervisor machines, each with a 1TB volume. I use LVM
> on top of the 1TB volume to carve out LVs for each VM harddrive.
>
> Then I have DRBD replicating each LV. So, currently I have 14 DRBD
> devices, I add a new DRBD resource whenever I create a new VM.
>
> This allows each VM to migrate from one hypervisor to the other
> independently. All the DRBD resources are setup for dual primary, this
> is needed to support Xen live migration.
>
> I let Hearbeat manage the VMs and I use the drbd: storage type for the
> Xen VMs, so Xen can handle the DRBD resources. This gives me failover
> for all the VMs, as well as manual live migration. Currently I run
> half the VMs on each hypervisor 7/7, to spread the load, of course
> Hearbeat will boot up the VMs on the remaining hypervisor if one of
> the systems fail. When I perform maintenance, I can put a Heartbeat
> node into standby and the VMs live migrate.
>
> This has been a very stable configuration for me.