From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:47805) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UCWMW-0008Pb-Ik for qemu-devel@nongnu.org; Mon, 04 Mar 2013 09:27:38 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UCWMR-0005hS-Ay for qemu-devel@nongnu.org; Mon, 04 Mar 2013 09:27:32 -0500 Received: from mx1.redhat.com ([209.132.183.28]:5692) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UCWMR-0005h2-3U for qemu-devel@nongnu.org; Mon, 04 Mar 2013 09:27:27 -0500 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r24ERQfr026689 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 4 Mar 2013 09:27:26 -0500 Date: Mon, 4 Mar 2013 14:27:21 +0000 From: "Daniel P. Berrange" Message-ID: <20130304142721.GT8123@redhat.com> References: <51349A64.2020003@redhat.com> <20130304130937.GR8123@redhat.com> <20130304140453.GD3929@dhcp-200-207.str.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20130304140453.GD3929@dhcp-200-207.str.redhat.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [RFC] qcow3 format in libvirt Reply-To: "Daniel P. Berrange" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: libvir-list@redhat.com, =?utf-8?Q?J=C3=A1n?= Tomko , qemu-devel@nongnu.org On Mon, Mar 04, 2013 at 03:04:53PM +0100, Kevin Wolf wrote: > Am 04.03.2013 um 14:09 hat Daniel P. Berrange geschrieben: > > On Mon, Mar 04, 2013 at 01:58:12PM +0100, J=C3=A1n Tomko wrote: > > > Before posting another version of my patches [1], attempting to add > > > support for the new qcow format to libvirt, I would like to know if= this > > > sounds reasonable: > > >=20 > > > A new format named 'qcow3' would be added, along with a > > > sub-element for target. > > >=20 > > > > > > qcow3test > > > > > > > > > 8 > > > > > > /var/lib/libvirt/images/qcow3test > > > > > > > > > > > > > > > > > > > > >=20 > > > I think that libvirt shouldn't care if the features are compatible = or > > > incompatible, as we don't know what features are supported by the > > > hypervisor. Would the features be any good as tri-state (on, off, d= efault?). > > >=20 > > > While the qcow3 format is handled by the qcow2 driver in QEMU, > > > should be enough for domains= , > >=20 > > We should use qcow3 everywhere IMHO, regardless of whether qcow2 > > technically works in this context. >=20 > I think it makes much more sense to deal with it the way qemu does > instead of inventing new names. This has much more of an (incompatible) > feature flag than of a different image format. So to fit it in your > proposed syntax: The issue is that QEMU is not the only thing that implements the qcow format. There are a number of other impls out there, and we can't just assume that they will all be providing a qcow2 driver that automagically opens a qcow3 image format. Just in the same way we didn't assume that a 'qcow' (version 1) driver would open a version 2 image. It so happens that with QEMU if you specify format=3Dqcow2 and give it a qcow3 image, QEMU will open it, but libvirt can't assume that, since this is a mere implementation detail. Hence libvirt must explicitly refer to 'qcow3' in the XML and map it to qcow2 if applicable when talking to QEMU. > But I guess you call all VMDKs just "vmdk", despite the fact that they > are really just a collection of different subformats. Right? Yes, but that is really a bug in our representation of vmdk. Daniel --=20 |: http://berrange.com -o- http://www.flickr.com/photos/dberrange= / :| |: http://libvirt.org -o- http://virt-manager.or= g :| |: http://autobuild.org -o- http://search.cpan.org/~danberr= / :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vn= c :|