Il 29/01/2013 14:27, Stefan Hajnoczi ha scritto: >> > and in step 5, may need export the delta data, not the whole disk >> > data. > NBD doesn't have a way to perform bdrv_is_allocated(). Either we need > to enhance the protocol or we need to add a QMP command to read > the allocation bitmap for an image. I'm a little hesitant about sending > the bitmap or allocation extent information over QMP (JSON) but it might > be doable.
I'm planning to add offline mirroring to qemu-img. If you use an NBD server as the destination, it can be used to send only the delta between two snapshots via NBD. I think this is the opposite of what you suggested, which is to run qemu-nbd on the image and query the server. Paolo
