From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:43367) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S227M-0003aR-HW for qemu-devel@nongnu.org; Mon, 27 Feb 2012 10:04:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S227G-0004EQ-Li for qemu-devel@nongnu.org; Mon, 27 Feb 2012 10:04:00 -0500 Received: from mx1.redhat.com ([209.132.183.28]:20818) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S227G-0004Ct-Dt for qemu-devel@nongnu.org; Mon, 27 Feb 2012 10:03:54 -0500 Message-ID: <4F4B9B54.7070700@redhat.com> Date: Mon, 27 Feb 2012 16:03:48 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <20120224170143.78f55d3e@doriath.home> <8eaeb022-ea20-4823-886a-e629bce1c776@zmail16.collab.prod.int.phx2.redhat.com> <20120227091215.7849e558@doriath.home> <4F4B7BCD.6000808@redhat.com> <20120227100645.3f36d52d@doriath.home> <4F4B95A5.3000804@redhat.com> <4F4B9761.3010601@codemonkey.ws> <4F4B9931.30708@redhat.com> <4F4B9A46.3090706@codemonkey.ws> In-Reply-To: <4F4B9A46.3090706@codemonkey.ws> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] drive transactions (was Re: [PATCH 2/2 v2] Add the blockdev-reopen and blockdev-migrate commands) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: kwolf@redhat.com, Jeff Cody , mtosatti@redhat.com, armbru@redhat.com, qemu-devel@nongnu.org, Federico Simoncelli , Luiz Capitulino On 02/27/2012 03:59 PM, Anthony Liguori wrote: > The problem is that the current commands are not designed well. For > instance, multi-snapshot could look like: > > block-freeze ide0-hd0 > block-freeze ide1-hd1 > block-reopen ide0-hd0 my-new-file0.qcow2 > block-reopen ide1-hd1 my-new-file1.qcow2 > block-unfreeze ide1-hd1 > block-unfreeze ide1-hd0 > > This would work regardless of whether the commands were implemented > asynchronously within QEMU too. This looks good, too. Positive: maps well to fsfreeze/thaw with help from the guest agent. Negative: you have to specify the devices three times. Overall, I think I like it. However, you need to add freeze/unfreeze capabilities to the block layer. Not hard, but one more thing to do. Paolo