protocol: { "driver": "file", "filename": "/var/lib/libvirt/images/i.qcow2", "size": 42 } format: { "driver": "qcow2", "file": "0123456789ABCDEF0123456789ABCDE", "size": 1337, "backing-file": "nbd://example.com:1234", "backing-fmt": "raw" }