From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49218) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aGVWp-0005gD-KT for qemu-devel@nongnu.org; Tue, 05 Jan 2016 12:36:16 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aGVWm-0002q6-EL for qemu-devel@nongnu.org; Tue, 05 Jan 2016 12:36:15 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37175) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aGVWm-0002pw-90 for qemu-devel@nongnu.org; Tue, 05 Jan 2016 12:36:12 -0500 References: <6ca84848.f052.15211b20317.Coremail.magazine.lihuiba@163.com> <568BCB6C.7010709@redhat.com> From: John Snow Message-ID: <568BFF0A.6050800@redhat.com> Date: Tue, 5 Jan 2016 12:36:10 -0500 MIME-Version: 1.0 In-Reply-To: <568BCB6C.7010709@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] qcow2 snapshot + resize List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake , lihuiba , "qemu-devel@nongnu.org" On 01/05/2016 08:55 AM, Eric Blake wrote: > On 01/05/2016 05:10 AM, lihuiba wrote: > >>>> In our production environment, we need to extend a qcow2 image with >>>> snapshots in it. > >>> The thing is that one would need to update all the inactive L1 tables. I >>> don't think it should be too difficult, it's just that apparently so far >>> nobody ever had the need for this feature. > > Is resizing a snapshot really what you want? Ideally, a snapshot tracks > the data from a point in time, including the metadata of the size being > tracked at that time. Extending the snapshots then reverting to that > snapshot means your guest would see a larger disk on revert than it did > at the time the snapshot was created, which guests might not handle very > well. > Unless reverting to a snapshot also implied undoing the re-size.