Re: [libvirt-users] Excluding RAW disk from snapshot
On Thu, Aug 2, 2012 at 11:58 AM, Eric Blake <eblake@redhat.com> wrote:
On 08/02/2012 10:53 AM, Trey Dockendorf wrote:
Did you mean for this to go to the list? Others might benefit from the answer.
<domainsnapshot> <name>20120802</name> <description>oVirt 3.1 upgrade</description> <disks> <disk name='vda' snapshot='yes' /> <disk name='vdb' snapshot='no' /> </disks> </domainsnapshot>
When I try the snapshot I get this error...
Here's the new XML
<domainsnapshot> <name>20120802</name> <description>oVirt 3.1 upgrade</description> <disks> <disk name='vdb' snapshot='no' /> </disks> </domainsnapshot>
Ah, right - snapshot is a tri-state: 'no', 'internal', and 'external', so 'yes' is not a valid state (although currently only 2 of the 3 states are supported for qemu: 'no' and 'external').
Now I get this error
# virsh snapshot-create --disk-only dc-vmarchitect dc-vmarchitect_ss.xml error: operation failed: Failed to take snapshot: unknown command: 'snapshot_blkdev'
That's a sign of your qemu being too old to support disk snapshots (older qemu only supports system checkpoint internal snapshots).
I do not know if this could be an issue, but after this wasn't working with libvirt-0.9.4, I did "yum update qemu-img qemu-kvm libvirt" and am now at the versions listed in previous email. I did not do a full system upgrade or reboot as this is a heavily loaded production system. Is this the case where the VM is running as the previous version of qemu-kvm ?
Thanks - Trey
-- Eric Blake eblake@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
Replying back to list, accidently missed reply-all. 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? If this isn't something yet supported in EL6.3, which I hope it is, is there any other way to perform a snapshot and exclude a disk aside from temporarily detaching it from the VM? Thanks - Trey
On 08/02/2012 08:57 PM, Trey Dockendorf wrote:
On Thu, Aug 2, 2012 at 11:58 AM, Eric Blake <eblake@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@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
participants (2)
-
Eric Blake -
Trey Dockendorf