On 04/04/2016 22:03, Alex Bligh wrote: > So qemu-nbdserver has some idea of 'dirtiness', and you want > to publish that, and the consumer is qemu (and only qemu), > because only qemu knows what 'dirtiness' means in the > sense the server provides it? The consumer is not QEMU; the consumer is backup software which is not part of QEMU (and could even be proprietary, ugh). Paolo