libvirt users - Feb 2013 - How to copy snapshots of a VM to the other computer.

Currently, I've tried to move qemu VM image to a new computer.

So, I copied VM image files in /var/lib/libvirt/images, VM xml files in
/etc/libvirt/qemu, VM snapshot files in /var/lib/libvirt/qemu/snapshot to
the same places at the new computer.

Everything is OK except snapshot!!

When I use "qemu-img info" for the copied VM image, I can see the
snapshot
list in the result as shown below:


root at doc-scheduler:/var/lib/libvirt/images# qemu-img info VM22.img
image: VM22.img
file format: qcow2
virtual size: 10G (10737418240 bytes)
disk size: 1.7G
cluster_size: 65536
Snapshot list:
ID        TAG                 VM SIZE                DATE       VM CLOCK
1         VM22_A                 228M 2013-01-31 10:06:45   00:06:38.110


But, when I use "virsh snapshot-list " for the copied VM, the result
is
empty as follows:

root at doc-scheduler:~# virsh snapshot-list VM22
 Name                 Creation Time             State
------------------------------------------------------------


and of course, I can't revert to the snapshot.

Please let me know how I can copy my snapshots to the new machine.

Thanks.
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On 02/01/2013 12:13 AM, Jonghee Youn wrote:
> Currently, I've tried to move qemu VM image to a new computer.
> 
> So, I copied VM image files in /var/lib/libvirt/images,
This part is fine.
> VM xml files in
> /etc/libvirt/qemu, VM snapshot files in /var/lib/libvirt/qemu/snapshot to
> the same places at the new computer.
That is not the recommended way to do things - it _might_ work if you
are using the same version of libvirt on both computers, and libvirtd is
_not_ running on the destination.  However, the _preferred_ method, and
the only way that is guaranteed to work if libvirtd is newer on the
destination than on the source, or if libvirtd is already running on the
destination, is to use various 'virsh *dumpxml' commands on the source
followed by 'virsh *define' on the destination.
> 
> Everything is OK except snapshot!!
> 
> When I use "qemu-img info" for the copied VM image, I can see the
snapshot
> list in the result as shown below:
> 
> 
> root at doc-scheduler:/var/lib/libvirt/images# qemu-img info VM22.img
> image: VM22.img
> file format: qcow2
> virtual size: 10G (10737418240 bytes)
> disk size: 1.7G
> cluster_size: 65536
> Snapshot list:
> ID        TAG                 VM SIZE                DATE       VM CLOCK
> 1         VM22_A                 228M 2013-01-31 10:06:45   00:06:38.110
> 
> 
> But, when I use "virsh snapshot-list " for the copied VM, the
result is
> empty as follows:
> 
> root at doc-scheduler:~# virsh snapshot-list VM22
>  Name                 Creation Time             State
> ------------------------------------------------------------
> 
> 
> and of course, I can't revert to the snapshot.
> 
> Please let me know how I can copy my snapshots to the new machine.
Do 'virsh snapshot-list $dom --tree' on the source.  Then, for each
snapshot in the list in tree order, do 'virsh snapshot-dumpxml $dom
$name --security-info > file' on the source, then 'virsh
snapshot-create
$dom file --redefine' on the destination.  If you also want to preserve
which snapshot is current, use 'virsh snapshot-current $dom --name' on
the source, the use the --current flag when re-creating that particular
name on the destination.

Someday, I'd like to make it easier to do domain migration, including
snapshots, all from a single virsh command, but we aren't quite there yet.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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