As far as I can see there's no way to create a snapshot and either a) inherit the runtime options from the original image b) specify a new set of options
This comment in external_snapshot_prepare() before calling bdrv_open() suggests that the problem is known but the discussion was postponed. /* TODO Inherit bs->options or only take explicit options with an * extended QMP command? */ I would like to retake this and make it possible. I discussed it briefly with Stefan on IRC and he said that Kevin might have some ideas. In principle extending the QMP command sounds as simple as adding 'options': 'BlockdevOptions' to 'blockdev-snapshot-sync', but it's surely more complicated than that :) Is the 'BlockdevOptions' API even stable? Berto