Hi, After upgrading to libvirt 0.8.1, I can no longer create empty volumes with no backing store and an explicit format of qcow2. This XML volume definition: <volume> <name>testserverb-data2.img</name> <allocation>0</allocation> <capacity units='G'>20</capacity> <target> <format type='qcow2'/> <permissions> <owner>107</owner> <group>107</group> <mode>0744</mode> </permissions> </target> </volume> yields the error "Cannot run /usr/bin/qemu-img to create /data/testserverb- data.img: Invalid argument" In /var/log/messages on the qemu host I can find the following snippet after that: error : virRunWithHook:933 : internal error '/usr/bin/qemu-img create -f qcow2 /data/testserverb-data.img 0K' exited with non-zero status 1 and signal 0: qemu-img: Image creation needs a size parameter#012 error : virStorageBackendCreateExecCommand:537 : Cannot run /usr/bin/qemu-img to create /data/testserverb-data.img: Invalid argument error : qemudClientReadBuf:1653 : gnutls_record_recv: A TLS packet with unexpected length was received. If I leave out the <format> element and/or specify a <backingStore> element for the volume, it works again. (I suppose the backing store makes it work because in that case qemu-img does not need a size parameter...) The host system is a vanilla Fedora Core 12 system (aside from the upgraded libvirt). Regards, Guido Winkelmann