From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:58302) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TkxNF-0007xr-Lt for qemu-devel@nongnu.org; Tue, 18 Dec 2012 08:38:24 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TkxNB-0007Qs-Qt for qemu-devel@nongnu.org; Tue, 18 Dec 2012 08:38:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:62384) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TkxNB-0007Qc-Je for qemu-devel@nongnu.org; Tue, 18 Dec 2012 08:38:17 -0500 Date: Tue, 18 Dec 2012 14:38:06 +0100 From: Stefan Hajnoczi Message-ID: <20121218133806.GA6697@stefanha-thinkpad.redhat.com> References: <1353935123-24199-1-git-send-email-benoit@irqsave.net> <1353935123-24199-2-git-send-email-benoit@irqsave.net> <20121211113234.GH796@stefanha-thinkpad.muc.redhat.com> <20121212155737.GA3478@irqsave.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20121212155737.GA3478@irqsave.net> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [RFC V3 01/24] qcow2: Add deduplication to the qcow2 specification. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?iso-8859-1?Q?Beno=EEt?= Canet Cc: kwolf@redhat.com, Stefan Hajnoczi , qemu-devel@nongnu.org On Wed, Dec 12, 2012 at 04:57:38PM +0100, Beno=EEt Canet wrote: > > Can you foresee the need to use a different hash algorithm in the fut= ure > > and should we add a hash_algo enum field to the dedup QCOW2 header > > extension? >=20 > Yes I foresee the future use of faster hash function like SHA3 or Skein. >=20 > I also think an alternate deduplication mechanism where lookups are don= e > on disk in order to be able to deduplicate very large volume could be a= dded. >=20 > 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