From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45525) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UpBk3-00010T-QX for qemu-devel@nongnu.org; Wed, 19 Jun 2013 02:19:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UpBk2-0007bM-M7 for qemu-devel@nongnu.org; Wed, 19 Jun 2013 02:19:39 -0400 Received: from e28smtp01.in.ibm.com ([122.248.162.1]:51809) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UpBk2-0007Yb-0n for qemu-devel@nongnu.org; Wed, 19 Jun 2013 02:19:38 -0400 Received: from /spool/local by e28smtp01.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 19 Jun 2013 11:42:25 +0530 Received: from d28relay03.in.ibm.com (d28relay03.in.ibm.com [9.184.220.60]) by d28dlp03.in.ibm.com (Postfix) with ESMTP id 1F2141258043 for ; Wed, 19 Jun 2013 11:48:05 +0530 (IST) Received: from d28av01.in.ibm.com (d28av01.in.ibm.com [9.184.220.63]) by d28relay03.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r5J6JCWq30670882 for ; Wed, 19 Jun 2013 11:49:13 +0530 Received: from d28av01.in.ibm.com (loopback [127.0.0.1]) by d28av01.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r5J6J5ex012919 for ; Wed, 19 Jun 2013 06:19:05 GMT Message-ID: <51C14D48.7040907@linux.vnet.ibm.com> Date: Wed, 19 Jun 2013 14:18:48 +0800 From: Wenchao Xia MIME-Version: 1.0 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> <20130618142037.GO7649@stefanha-thinkpad.redhat.com> In-Reply-To: <20130618142037.GO7649@stefanha-thinkpad.redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 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: Stefan Hajnoczi 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 于 2013-6-18 22:20, Stefan Hajnoczi 写道: > 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. > Several deletion in transaction equals to several calls of 'blockdev-snapshot-delete-internal-sync', unlike creation, so I hope not add it which have rollback issue. > 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. > Maybe the caller can encapsulate a batch interface at its level. > Stefan > -- Best Regards Wenchao Xia