[libvirt-users] Snapshot of single block device

Hello! I have a guest with one qcow2 disk image (vda) and one physical partition (sda) from host. When I'm trying to get snapshot with: virsh snapshot-create-as ..... It fails with message: error: unsupported configuration: source for disk 'sda' is not a regular file; refusing to generate external snapshot name I understand, that it is not possible to make a snapshot of physical device, but it is enough for me to take snapshot of vda. How to force virsh to ignore sda ? best regards Jarek