On Tue, Feb 13, 2018 at 01:38:34PM +0100, Lentes, Bernd wrote: [...] The guest doesn't have to be shutdown. First of all the term "snapshot" is a bit overloaded. There are different kinds of snapshots. Refer slide-7 here[*]. In your case, since you want to take a snapshot of a raw disk image, we'll be talk about "external snapshots". So let's spell out what exactly happens when you try to take live snapshot of a raw disk image. If you have a disk image (to which live QEMU is writing): A.raw (live QEMU) When you create an "external snapshot" as below: $ virsh snapshot-create-as --domain vm1 disk-state1 \ --diskspec vda,file=/export/images/B.qcow2 \ --disk-only --atomic You will get the following: A.raw <-- B.qcow2 (live QEMU) What it means is the original A.raw is turned into a read-only backing file. A new QCOW2 "overlay" (B.qcow2) is created, and all the new writes from now on will happen in B.qcow2. In the above scenario, `virsh snapshot-revert` will not work (as of now). If you now want to rever to A.raw, you have to: (1) Shutdown the guest: $ virsh shutdown vm1 (2) Edit the guest XML so that it now points to A.raw: $ virsh edit vm1 And update the 'source file' attribute: ... <disk type='file' device='disk'> <driver name='qemu' type='raw'/> <source file='/my/A.raw'/> ... (3) Start the guest again: $ virsh start vm1 * * * If you want to take backups, there's a cleaner way: https://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit The above is possible with QEMU 2.1 (and above), libvirt-1.2.9 (and above). So, in your environment, you have to upgrade. I answered your questions above to keep them in one place. (Yes, you're right — you have to edit the XML file and point to the original disk.) The command `virsh snapshot-revert` works only with "internal snapshots" — where your original and the delta, all of them reside in the single QCOW2 file. PS: I also fixed the quoting in your email, it was a bit off. [*] https://kashyapc.fedorapeople.org/virt/lc-2012/lceu-2012-virt-snapshots-k... -- /kashyap

----- On Feb 15, 2018, at 12:53 PM, Kashyap Chamarthy kchamart(a)redhat.com wrote: Hi Kashyap, thanks for your quick and detailed answers. Just to be complete. The procedure in the above mentioned link does work with my old software ? pc59093:~ # rpm -qa|grep -iE 'libvirt|kvm' libvirt-cim-0.5.12-0.7.16 libvirt-python-1.2.5-1.102 libvirt-client-1.2.5-15.3 kvm-1.4.2-47.1 sles-kvm_en-pdf-11.4-0.33.1 libvirt-1.2.5-15.3 Bernd Helmholtz Zentrum München

----- On Feb 16, 2018, at 3:01 PM, Kashyap Chamarthy kchamart(a)redhat.com wrote: Hi, again thanks for your quick answer. I had a look on https://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit and i liked it. I'm thinking of upgrading my systems to SLES 12 SP3. With that i have qemu 2.9.1 and libvirt 3.3.0, so it should work. Does this procedure also work with raw files ? Bernd Helmholtz Zentrum München

Hi, i just realized that i have a guest with two disks. What would be the appropiate way to snapshot both of them ? virsh snapshot-create-as --domain guest --diskspec vda,file=/path/to/snapshot/snapshot1.qcow2 -disk-only --atomic && virsh snapshot-create-as --domain guest --diskspec vdb,file=/path/to/snapshot/snapshot2.qcow2 -disk-only --atomic or virsh snapshot-create-as --domain guest --diskspec vda,file=/path/to/snapshot/snapshot1.qcow2 --diskspec vdb,file=/path/to/snapshot/snapshot2.qcow2 --disk-only --atomic Bernd Helmholtz Zentrum Muenchen Deutsches Forschungszentrum fuer Gesundheit und Umwelt (GmbH) Ingolstaedter Landstr. 1 85764 Neuherberg www.helmholtz-muenchen.de Aufsichtsratsvorsitzende: MinDir'in Baerbel Brumme-Bothe Geschaeftsfuehrer: Prof. Dr. Guenther Wess, Heinrich Bassler, Dr. Alfons Enhsen Registergericht: Amtsgericht Muenchen HRB 6466 USt-IdNr: DE 129521671