On 03/12/2011 11:51 PM, Chunqiang Tang wrote:
In short, FVD's internal snapshot achieves the ideal properties of G1-G6,
by 1) using the reference count table to only track "static" snapshots, 2)
not keeping the reference count table in memory, 3) not updating the
on-disk "static" reference count table when the VM runs, and 4)
efficiently tracking dynamically allocated blocks by piggybacking on FVD's
other features, i.e., its journal and small one-level lookup table.
Are you assuming snapshots are read-only?
It's not clear to me how this would work with writeable snapshots. It's
not clear to me that writeable snapshots are really that important, but
this is an advantage of having a refcount table.
External snapshots are essentially read-only snapshots so I can
understand the argument for it.
Regards,
Anthony Liguori
Regards,
ChunQiang (CQ) Tang
Homepage: http://www.research.ibm.com/people/c/ctang
