From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=40748 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Otavr-0001Jn-4w for qemu-devel@nongnu.org; Thu, 09 Sep 2010 02:48:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1Otavp-0006dj-Ra for qemu-devel@nongnu.org; Thu, 09 Sep 2010 02:48:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:31812) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1Otavp-0006de-JC for qemu-devel@nongnu.org; Thu, 09 Sep 2010 02:48:25 -0400 Message-ID: <4C888328.4050201@redhat.com> Date: Thu, 09 Sep 2010 09:48:08 +0300 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format References: <1283767478-16740-1-git-send-email-stefanha@linux.vnet.ibm.com> <4C84E738.3020802@codemonkey.ws> <4C865187.6090508@redhat.com> <4C865CFE.7010508@codemonkey.ws> <4C8663C4.1090508@redhat.com> <4C866773.2030103@codemonkey.ws> <4C86BC6B.5010809@codemonkey.ws> <4C874812.9090807@redhat.com> <4C87860A.3060904@codemonkey.ws> <4C888287.8020209@redhat.com> In-Reply-To: <4C888287.8020209@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Kevin Wolf , Stefan Hajnoczi , qemu-devel@nongnu.org On 09/09/2010 09:45 AM, Avi Kivity wrote: >> >> A new format doesn't introduce much additional complexity. We >> provide image conversion tool and we can almost certainly provide an >> in-place conversion tool that makes the process very fast. > > It requires users to make a decision. By the time qed is ready for > mass deployment, 1-2 years will have passed. How many qcow2 images > will be in the wild then? How much scheduled downtime will be > needed? How much user confusion will be caused? > > Virtualization is about compatibility. In-guest compatibility first, > but keeping the external environment stable is also important. We > really need to exhaust the possibilities with qcow2 before giving up > on it. > btw, if we were starting from scratch, I'd definitely pick qed over qcow2. But we aren't starting from scratch (if we did, we wouldn't be doing x86 either). -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.