> From: Paolo Bonzini [mailto:pbonz...@redhat.com] > On 20/09/2016 15:37, Pavel Dovgalyuk wrote: > >> c) no rrsnapshot implies -snapshot: > >> without overlay: > >> -drive file=disk.raw,if=none,id=img-direct > >> -drive driver=blkreplay,if=none,image=img-direct,id=img-blkreplay > >> > >> with overlay: > >> -drive file=foo.qcow2,if=none,id=img-direct > >> -drive driver=blkreplay,if=none,image=img-direct,id=img-blkreplay > >> -icount ...,rrsnapshot=snapname > > > > But how record will create this overlay? > > This method requires creating overlay manually, because backing file is > > not specified at all. > > You create it manually, or you just use a .qcow2 file to begin with for > your image. Then: > > 1) if you specify no snapshot, a temporary .qcow2 file is created on top > so data is not destroyed > > 2) if you specify a snapshot, that snapshot is preserved (so you don't > lose the base state even though the file changes)
Now I see. This seems ok, but: - this approach adds some garbage to original disk image - won't work with raw images Pavel Dovgalyuk
