4:35 a.m.
Does libvirt support snapshotting when the virtual disk comes from a vmdk file?
http://wiki.libvirt.org/page/Snapshots#Desired_functionality seems to say no, since it
says "'virsh snapshot', which requires all disk images to be qcow2".
OTOH, man virsh, http://libvirt.org/formatsnapshot.html, and
http://libvirt.org/formatdomain.html#elementsDisks seem to indicate more flexibility,
though I see nothing about vmdk.
If there is support for vmdk, is it just for external snapshots, or do internal snapshots
work?
Currently running libvirt 0.9.12, qemu-kvm 1.1.2 (though I could use vmware workstation),
linux kernel 3.2.0.
Thanks.
Ross Boylan
11:24 a.m.
On Sat, May 30, 2015 at 02:35:51AM +0000, Boylan, Ross wrote:
Does libvirt support snapshotting when the virtual disk comes from a
vmdk file?
From my quick test (refer below), seems like you can at-least use VMDK
as a backing file.
http://wiki.libvirt.org/page/Snapshots#Desired_functionality seems
to
say no, since it says "'virsh snapshot', which requires all disk
images to be qcow2".
OTOH, man virsh, http://libvirt.org/formatsnapshot.html, and
http://libvirt.org/formatdomain.html#elementsDisks seem to indicate
more flexibility, though I see nothing about vmdk.
If there is support for vmdk, is it just for external snapshots, or do
internal snapshots work?
From my quick test (for offline disks with `qemu-img`), it does seem
to
work:
$ qemu-img create -f vmdk base.vmdk 1G
$ qemu-img create -f qcow2 -o \
'backing_file=./base.vmdk,backing_fmt=vmdk' ./overlay1.qcow2
$ qemu-img info overlay1.qcow2
image: overlay1.qcow2
file format: qcow2
virtual size: 1.0G (1073741824 bytes)
disk size: 196K
cluster_size: 65536
backing file: ./base.vmdk
backing file format: vmdk
Format specific information:
compat: 1.1
lazy refcounts: false
And, as near as I know, internal snapshots are a feature of qcow2 format.
Currently running libvirt 0.9.12, qemu-kvm 1.1.2 (though I could use
vmware workstation), linux kernel 3.2.0.
--
/kashyap
12:21 p.m.
On Mon, Jun 01, 2015 at 11:24:49AM +0200, Kashyap Chamarthy wrote:
On Sat, May 30, 2015 at 02:35:51AM +0000, Boylan, Ross wrote:
> Does libvirt support snapshotting when the virtual disk comes from a
> vmdk file?
Also, Stefan Hajnoczi from the QEMU project, points out:
QEMU's implementations of all formats besides raw, qcow2, and qed
are designed for import/export. They are not designed for
high-performance parallel I/O which you want for running guests. So
it works but it can be much slower than using raw/qcow2 only.
So it works but it can be much slower than using raw/qcow2 only.
--
/kashyap
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Kashyap Chamarthy