Hi,
(2010/09/29 5:24), Peter Doherty wrote:
Hi,
I'm using Centos5.5 on the host, and the KVM that's available in the repos. I'm using linux VMs too. My disk images are qcow2 files.
Here's what I want:
To be able to, on the host, create a snapshot of the guest's disk image, without shutting down the guest, so that I can then restore back to a point in time for the guest.
Yesterday, I heard a similar desire at the Virtualization End User Discussion @ LinuxCon Japan.
What you want to do is:
- taking the whole VM disk image snapshot
or
- just taking specific partition's image?
Generally speaking, taking the whole VM disk image snapshot without breaking
guest side consistency seems difficult.
Even though you restrict to a specific partition, you need to guarantee that
the file system is in an appropriate state.
Anybody has better ideas?
Takuya
I thought I could do this with the qcow2 images.
I've used:
qemu-img snapshot -c snapname disk_image.qcow2
to create the snapshot.
It doesn't work. The snapshots claim to be created, but if I shut down the guest, apply the snapshot
( qemu-img snapshot -a snapname disk_image.qcow2 )
the guest either:
a.) no longer boots (No bootable disk found)
b.) boots, but is just how it was when I shut it down (it hasn't reverted back to what it was like when the snapshot was made)
It makes no sense. I can sometimes apply the first snapshot, and it has worked...but subsequent snapshots are a no go.
One thing that is suspicious is that the VM SIZE and CLOCK are zero:
# qemu-img snapshot -l test1.qcow2
Snapshot list:
ID TAG VM SIZE DATE VM CLOCK
1 with100mb 0 2010-09-28 11:48:23 00:00:00.000
2 with200mb 0 2010-09-28 11:50:53 00:00:00.000
3 with300mb 0 2010-09-28 11:52:49 00:00:00.000
4 whenoff 0 2010-09-28 11:56:41 00:00:00.000
# /usr/libexec/qemu-kvm --help
QEMU PC emulator version 0.9.1 (kvm-83-maint-snapshot-20090205), Copyright (c) 2003-2008 Fabrice Bellard
I can't find much info about using qcow2 images when I search. Any help would be appreciated.
Thanks.
Peter
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