On Thu 13 Apr 2017 11:02:10 AM CEST, Kevin Wolf <kw...@redhat.com> wrote: > I think you still need it if you don't want to look at the refcount > blocks for every write. When you take an internal snapshot, you just > increase the refcount of the L2 tables at first and keep the contents > the same, including the subcluster information. On the first write to > the cluster, like with normal images you need to copy the whole > cluster, and whether this is the case is determined with the COPIED > flag. (The copy can actually keep unallocated/zeroed subclusters that > way, but data has to be copied for the whole cluster.) > > Of course, in all cases the COPIED flag is just an optimisation > because it's always possible to look at the refcount blocks, but I > don't think there is any difference between subclustered and > traditional images in this respect.
Exactly :) Berto
