On 30/09/2015 16:43, Jeff Cody wrote: > One issue is that QEMU will do mode!='existing' && sync!='full' for > drivers that do not support backing files (raw host devices, for > instance).
Yup, this can be used to get a mirror of future operations (the idea was to support things such as antiviruses, where the antivirus connects to QEMU via NBD). I think it's okay to ignore this case, since the resulting image is bogus anyway. What is interesting is only the stream of writes which you can get through NBD. Paolo