9:44 a.m.
Hi,
i can store the disk of a guest in a plain partition which isn't formatted.
That's no problem, i did it already several times, although the promised speed
increase didn't appear.
But is it possible to create from such a guest a snapshot in a .sn file using virsh ?
Regards,
Bernd
--
Bernd Lentes
Systemadministration
Institut für Entwicklungsgenetik
Gebäude 35.34 - Raum 208
HelmholtzZentrum münchen
bernd.lentes(a)helmholtz-muenchen.de
phone: +49 89 3187 1241
phone: +49 89 3187 3827
fax: +49 89 3187 2294
http://www.helmholtz-muenchen.de/idg
wer Fehler macht kann etwas lernen
wer nichts macht kann auch nichts lernen
Helmholtz Zentrum Muenchen
Deutsches Forschungszentrum fuer Gesundheit und Umwelt (GmbH)
Ingolstaedter Landstr. 1
85764 Neuherberg
www.helmholtz-muenchen.de
Aufsichtsratsvorsitzende: MinDirig'in Petra Steiner-Hoffmann
Stellv.Aufsichtsratsvorsitzender: MinDirig. Dr. Manfred Wolter
Geschaeftsfuehrung: Prof. Dr. med. Dr. h.c. Matthias Tschoep, Heinrich Bassler, Kerstin
Guenther
Registergericht: Amtsgericht Muenchen HRB 6466
USt-IdNr: DE 129521671
10:27 a.m.
On 4/3/19 9:44 AM, Lentes, Bernd wrote:
Hi,
i can store the disk of a guest in a plain partition which isn't formatted.
That's no problem, i did it already several times, although the promised speed
increase didn't appear.
But is it possible to create from such a guest a snapshot in a .sn file using virsh ?
It is possible to create an external snapshot (an internal one is not
possible, unless you stored the guest disk as qcow2 format embedded
inside the partition rather than directly as raw format). Note that
when you create an external snapshot, the partition becomes a read-only
point in time (no further updates to that partition), and your new
file.sn qcow2 wrapper file created by the snapshot operation stores all
subsequent guest writes. (Well, unless you decide to do a commit
operation to push the changes from the overlay back into the base file
and get rid of the overlay)
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
11:57 a.m.
----- On Apr 3, 2019, at 5:27 PM, Eric Blake eblake(a)redhat.com wrote:
It is possible to create an external snapshot (an internal one is
not
possible, unless you stored the guest disk as qcow2 format embedded
inside the partition rather than directly as raw format). Note that
when you create an external snapshot, the partition becomes a read-only
point in time (no further updates to that partition), and your new
file.sn qcow2 wrapper file created by the snapshot operation stores all
subsequent guest writes. (Well, unless you decide to do a commit
operation to push the changes from the overlay back into the base file
and get rid of the overlay)
Hi Eric,
thanks for your answer.
i tried it:
virsh # snapshot-create-as --disk-only --name sn --domain sim
error: unsupported configuration: source for disk 'vdb' is not a regular file;
refusing to generate external snapshot name
This is the snippet from the conf for the guest:
<disk type='block' device='disk'>
<driver name='qemu' type='raw' cache='none'
io='native'/>
<source dev='/dev/vg_san/lv_sim'/>
<backingStore/>
<target dev='vdb' bus='virtio'/>
<alias name='virtio-disk1'/>
<address type='pci' domain='0x0000' bus='0x00'
slot='0x06' function='0x0'/>
</disk>
I'm running SLES 12 SP4 with libvirt 4.0.0-6.13.x86_64.
Any ideas ?
Bernd
Helmholtz Zentrum Muenchen
Deutsches Forschungszentrum fuer Gesundheit und Umwelt (GmbH)
Ingolstaedter Landstr. 1
85764 Neuherberg
www.helmholtz-muenchen.de
Aufsichtsratsvorsitzende: MinDirig'in Petra Steiner-Hoffmann
Stellv.Aufsichtsratsvorsitzender: MinDirig. Dr. Manfred Wolter
Geschaeftsfuehrung: Prof. Dr. med. Dr. h.c. Matthias Tschoep, Heinrich Bassler, Kerstin
Guenther
Registergericht: Amtsgericht Muenchen HRB 6466
USt-IdNr: DE 129521671
12:42 p.m.
On 4/4/19 11:57 AM, Lentes, Bernd wrote:
virsh # snapshot-create-as --disk-only --name sn --domain sim
error: unsupported configuration: source for disk 'vdb' is not a regular file;
refusing to generate external snapshot name
That just means that libvirt refuses to create a new block device name
(new file names are easy, new block devices not so much); so you'll have
to tell libvirt what filename (which may or may not be a block device)
to use instead, with the --diskspec parameter. Something like:
snapshot-create-as --disk-only --name sn --domain sim --diskspec
vdb,file=/path/to/file.sn
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
2059
days inactive
2060
days old
3 comments
2 participants
participants (2)
-
Eric Blake -
Lentes, Bernd