[libvirt-users] Excluding RAW disk from snapshot

[Eric Blake]

On 08/02/2012 08:57 PM, Trey Dockendorf wrote:
> On Thu, Aug 2, 2012 at 11:58 AM, Eric Blake <eblake at redhat.com> wrote:
> Could it be the case that since I upgraded libvirt and qemu while all
> the VMs were running, that the VM has to be restarted to take on the
> updated version's capability?

That is indeed true - updating the qemu-kvm package does NOT instantly
add new features to already-running VMs; to use those new features, you
have to shut down the VM and restart it under the new qemu-kvm binary
(you can, however, use live migration and/or [managed]save/restore as a
way of minimizing the guest downtime still moving to a newer qemu-kvm
binary, rather than having to boot the guest from scratch).

> 
> If this isn't something yet supported in EL6.3, which I hope it is,

My understanding is that RHEL 6.3 qemu does not support disk snapshots;
you have to use RHEV-M to get that feature from existing Red Hat
products.  If this is a problem for you, then open a support case with
Red Hat, as this upstream list is not in charge of what features Red Hat
chooses to backport or omit from its shipped version of qemu.

> is
> there any other way to perform a snapshot and exclude a disk aside
> from temporarily detaching it from the VM?

Not that I'm aware of.  The qemu 'savevm' monitor command which is used
for system checkpoints cannot exclude disks, and the only other snapshot
option requires a qemu that supports disk snapshots via the
'blockdev-snapshot-sync' monitor command.

-- 
Eric Blake   eblake at redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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