From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36498) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uowm5-00062S-4t for qemu-devel@nongnu.org; Tue, 18 Jun 2013 10:20:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Uowm1-0002Lr-OW for qemu-devel@nongnu.org; Tue, 18 Jun 2013 10:20:44 -0400 Received: from mail-wi0-x236.google.com ([2a00:1450:400c:c05::236]:49910) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uowm1-0002Ll-EE for qemu-devel@nongnu.org; Tue, 18 Jun 2013 10:20:41 -0400 Received: by mail-wi0-f182.google.com with SMTP id m6so3281670wiv.9 for ; Tue, 18 Jun 2013 07:20:40 -0700 (PDT) Date: Tue, 18 Jun 2013 16:20:37 +0200 From: Stefan Hajnoczi Message-ID: <20130618142037.GO7649@stefanha-thinkpad.redhat.com> References: <1371209999-15579-1-git-send-email-xiawenc@linux.vnet.ibm.com> <1371209999-15579-10-git-send-email-xiawenc@linux.vnet.ibm.com> <51BC3A10.6040001@redhat.com> <51BE81A6.1090202@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <51BE81A6.1090202@linux.vnet.ibm.com> Subject: Re: [Qemu-devel] [PATCH V2 09/12] qmp: add interface blockdev-snapshot-delete-internal-sync List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wenchao Xia Cc: kwolf@redhat.com, phrdina@redhat.com, famz@redhat.com, armbru@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com, pbonzini@redhat.com, lcapitulino@redhat.com, dietmar@proxmox.com On Mon, Jun 17, 2013 at 11:25:26AM +0800, Wenchao Xia wrote: > 于 2013-6-15 17:55, Eric Blake 写道: > >Should this command be made available via 'transaction'? That is, if I > >have a two-disk VM, and use 'transaction' to take a snapshot of both > >disks at once, shouldn't I also have a way to delete the snapshots of > >both at once, or gracefully fail without data loss if the second one has > >problems? > > I think adding it in transaction is not very useful but brings more > complexity. Transcation is used to guareentee all operations are taken > in one time point, for example, snapshot creation use it to make sure > all are consistent to VM. But for deletion, this requirement do not > exist. I guess the problem is: can we make internal snapshot deletion transactional? It's hard to do rollback for snapshot deletion. But batching is definitely useful for doing 'delvm' in QMP. I just don't think transactions help. We just need a 'delvm' equivalent in QMP. Stefan