[libvirt-users] QEMU IMG vs Libvirt block commit

[Erlon Cruz]

Hi folks,

I'm having a issue in the standard NFS driver on OpenStack, that uses
qemu-img and libvirt to create snapshots of volumes. It uses qemu-img in
the Controller to manage the snapshots when the volume is not attached
(offline) or calls the Compute (which calls libvirt) to manage snapshots if
the volume is attached (online). When I try to create/delete snapshots from
a snapshot chain. There are 3 situations:

1 - I create/delete the snapshots in Cinder (it uses qemu-img). It goes OK!
I can delete and I can create snapshots.
2 - I create/delete the snapshots, in online mode (it uses libvirt). It
goes Ok, as weel.
3 - I create the snapshots in Cinder (offline) and delete then in online
mode (using libvirt), then it fails with this message[1]:

libvirtError: invalid argument: could not find image
'volume-13cb83a2-880f-40e8-b60e-7e805eed76f9.d024731c-bdc3-4943-91c0-215a93ee2cf4'
in chain for
'/opt/stack/data/nova/mnt/a3b4c6ddd9bf82edd4f726872be58d05/volume-13cb83a2-880f-40e8-b60e-7e805eed76f9'

But, in this folder, there the backing files are there[2] and they are
chained as think it suppose to be[3].

The version for the 2 hosts in tests are:
Controller/Cinder node: qemu-img version 2.0.0 && libvirt 1.2.2-0ubuntu13
Compute node: qemu-img version 2.5.0 && libvirt-1.3.1-1ubuntu10

Is there any compatibility problem between libvirt and qemu-img snapshots?
Have you guys found any problem like that?

Erlon
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[1] http://paste.openstack.org/show/543270/
[2] http://paste.openstack.org/show/543273/
[3] http://paste.openstack.org/show/543274/
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