From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49740) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UpE9b-0006Eo-C0 for qemu-devel@nongnu.org; Wed, 19 Jun 2013 04:54:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UpE9Z-0005cL-Gd for qemu-devel@nongnu.org; Wed, 19 Jun 2013 04:54:11 -0400 Received: from e28smtp08.in.ibm.com ([122.248.162.8]:43208) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UpE9Y-0005bl-VA for qemu-devel@nongnu.org; Wed, 19 Jun 2013 04:54:09 -0400 Received: from /spool/local by e28smtp08.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 19 Jun 2013 14:15:42 +0530 Received: from d28relay04.in.ibm.com (d28relay04.in.ibm.com [9.184.220.61]) by d28dlp02.in.ibm.com (Postfix) with ESMTP id 24D793940043 for ; Wed, 19 Jun 2013 14:24:04 +0530 (IST) Received: from d28av05.in.ibm.com (d28av05.in.ibm.com [9.184.220.67]) by d28relay04.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r5J8rtp612779526 for ; Wed, 19 Jun 2013 14:23:55 +0530 Received: from d28av05.in.ibm.com (loopback [127.0.0.1]) by d28av05.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r5J8rvrO006653 for ; Wed, 19 Jun 2013 18:53:57 +1000 Message-ID: <51C17192.6050405@linux.vnet.ibm.com> Date: Wed, 19 Jun 2013 16:53:38 +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> <51C14D48.7040907@linux.vnet.ibm.com> <20130619074608.GC23822@stefanha-thinkpad.muc.redhat.com> In-Reply-To: <20130619074608.GC23822@stefanha-thinkpad.muc.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, Stefan Hajnoczi , armbru@redhat.com, qemu-devel@nongnu.org, pbonzini@redhat.com, lcapitulino@redhat.com, dietmar@proxmox.com 于 2013-6-19 15:46, Stefan Hajnoczi 写道: > On Wed, Jun 19, 2013 at 02:18:48PM +0800, Wenchao Xia wrote: >> 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. > > 'delvm' is a batch interface - it deletes internal snapshots that have > the same name across multiple devices. > > It's not as flexible as: > blkdev-internal-snapshot-delete drive0 drive2 drive4 > > Because that would allow you to specify specific drives. > Do you mean this interface should be changed as blkdev-internal-snapshot-delete devices_array name *id? It seems not much difference with following methods: for device in device_list: blkdev-internal-snapshot-delete device name > Stefan > -- Best Regards Wenchao Xia