Re: [Qemu-devel] [RFC V3 01/24] qcow2: Add deduplication to the qcow2 specification.

[Stefan Hajnoczi]

On Wed, Dec 12, 2012 at 04:57:38PM +0100, Benoît Canet wrote:
> > Can you foresee the need to use a different hash algorithm in the future
> > and should we add a hash_algo enum field to the dedup QCOW2 header
> > extension?
> 
> Yes I foresee the future use of faster hash function like SHA3 or Skein.
> 
> I also think an alternate deduplication mechanism where lookups are done
> on disk in order to be able to deduplicate very large volume could be added.
> 
> What would be the cleanest way to store this in the header extension ?
> bitmaps or two char fields ?

The header extension could have a uint8_t hash_algo field (and 3
reserved bytes that can be used in the future).

0 - SHA256
1 - Skein
...

Stefan