[CentOS-virt] RAID: by host or within KVM?

Sat Aug 11 16:42:36 UTC 2012
Emmanuel Noobadmin <centos.admin at gmail.com>

On 8/10/12, Kanwar Ranbir Sandhu <m3freak at thesandhufamily.ca> wrote:
> 1. Let the KVM host manage the drives (i.e. RAID with LVM on top) and just
> assign the single volume to OMV. OMV will see it as one HD.
> 2. Assign the individual drives to the OMV KVM, and let OMV manage the
> RAID creation, management, etc.

I usually go with #1 now because it makes the VM simpler and allows
add further VM easily.

> I'm not sure which one will perform better. My hunch is if the RAID
> management is left at the host level, I'll see better overall performance.
> Performance isn't exactly my number one goal here, but I don't want to
> kill
> it completely either by going the wrong way.
> On the other hand, if I let OMV do the RAID management for the media
> storage disks, I'll gain future flexibility because it'll be much easier
> to move OMV to bare metal.

You could probably plan for this by setting things up in advanced to
make it easier to move in the future.

Right now, for want of a better/simpler solution, I'm setting up
degraded mdadm raid 1 within the VM. The idea being that anytime I
want to move the VM to bare metal or another host, I could just add a
drive (or map one), let it sync, then shut it down, shift the drive
and theoretically  boot it up on the new machine.