On 01/27/2016 05:20 AM, Wido den Hollander wrote: > RBD supports cloning by creating a snapshot, protecting it and create > a child image based on that snapshot afterwards. > > The RBD storage driver will try to find a snapshot with zero deltas between > the current state of the original volume and the snapshot. > > If such a snapshot is found a clone/child image will be created using > the rbd_clone2() function from librbd. > > rbd_clone2() is available in librbd since Ceph version Dumpling (0.67) which > dates back to August 2013. > > It will use the same features, strip size and stripe count as the parent image. > > This implementation will only create a single snapshot on the parent image if > never changes. This reduces the amount of snapshots created for that RBD image > which benefits the performance of the Ceph cluster. > > During build the decision will be made to use either rbd_diff_iterate() or > rbd_diff_iterate2(). > > The latter is faster, but only available on Ceph versions after 0.94 (Hammer). > > Cloning is only supported if RBD format 2 is used. All images created by libvirt > are already format 2. > > If a RBD format 1 image is used as the original volume the backend will report > a VIR_ERR_OPERATION_UNSUPPORTED error. > > Signed-off-by: Wido den Hollander <wido@xxxxxxxxx> > --- > src/storage/storage_backend_rbd.c | 341 ++++++++++++++++++++++++++++++++++++++ > 1 file changed, 341 insertions(+) > ACK - pushed John -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list