[libvirt] domblkstat not working for qemu-kvm > 0.11

[Daniel P. Berrange]

On Tue, Feb 09, 2010 at 04:06:56PM +0100, Thomas Treutner wrote:
> Hi,
> 
> with all qemu-kvm > 0.11, virsh domblkstat is not working:
> 
> virsh -c qemu://node03/system domblkstat wp01 vdb :  invalid argument in no 
> stats found for device virtio-disk1
> 
> (vda, vdb etc. works with 0.11)
> 
> "virtio-disk1" seems to be a red herring:
> 
> virsh -c qemu://node03/system domblkstat wp01 virtio-disk1 : invalid argument 
> in invalid path: virtio-disk1
> 
> Most probably there have been made some changes with 0.12 libvirt does not 
> resemble yet. If you need more debugging output, just tell.

I've managed to reproduce it and figured out what's wrong. libvirt was
trying to match against the device name 'virtio-disk1' rather than against
the drive name 'drive-virtio-disk1' and so not finding the stats.

The reason its matching 'virtio-disk1' rather than 'vda' is that that is
the globally unique name libvirt gave to the 'vda' device. You can see
this now in the XML format <alias> element. In the future we will allow
you to actually pass the alias in directly, as an alternative to the
'vda' style name

Daniel
-- 
|: Red Hat, Engineering, London   -o-   http://people.redhat.com/berrange/ :|
|: http://libvirt.org  -o-  http://virt-manager.org  -o-  http://ovirt.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: GnuPG: 7D3B9505  -o-  F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|