From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45293) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c9Mfb-0006Bk-9V for qemu-devel@nongnu.org; Tue, 22 Nov 2016 20:48:20 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c9MfY-0000ci-71 for qemu-devel@nongnu.org; Tue, 22 Nov 2016 20:48:19 -0500 References: <1476971860-20860-1-git-send-email-zhang.zhanghailiang@huawei.com> <20161122103340.GA5970@stefanha-x1.localdomain> From: Hailiang Zhang Message-ID: <5834F547.8090208@huawei.com> Date: Wed, 23 Nov 2016 09:47:51 +0800 MIME-Version: 1.0 In-Reply-To: <20161122103340.GA5970@stefanha-x1.localdomain> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [Qemu-block] [PATCH RFC 0/7] COLO block replication supports shared disk case List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, kwolf@redhat.com, xiecl.fnst@cn.fujitsu.com, wency@cn.fujitsu.com, Juan Quintela , "Dr . David Alan Gilbert" , mreitz@redhat.com, stefanha@redhat.com, Amit Shah , pbonzini@redhat.com On 2016/11/22 18:33, Stefan Hajnoczi wrote: > On Thu, Oct 20, 2016 at 09:57:33PM +0800, zhanghailiang wrote: >> COLO block replication doesn't support the shared disk case, >> Here we try to implement it. >> >> Just as the scenario of non-shared disk block replication, >> we are going to implement block replication from many basic >> blocks that are already in QEMU. >> The architecture is: >> >> virtio-blk || .---------- >> / || | Secondary >> / || '---------- >> / || virtio-blk >> / || | >> | || replication(5) >> | NBD --------> NBD (2) | >> | client || server ---> hidden disk <-- active disk(4) >> | ^ || | >> | replication(1) || | >> | | || | >> | +-----------------' || | >> (3) |drive-backup sync=none || | >> --------. | +-----------------+ || | >> Primary | | | || backing | >> --------' | | || | >> V | | >> +-------------------------------------------+ | >> | shared disk | <----------+ >> +-------------------------------------------+ >> 1) Primary writes will read original data and forward it to Secondary >> QEMU. >> 2) The hidden-disk will buffers the original content that is modified >> by the primary VM. It should also be an empty disk, and >> the driver supports bdrv_make_empty() and backing file. >> 3) Primary write requests will be written to Shared disk. >> 4) Secondary write requests will be buffered in the active disk and it >> will overwrite the existing sector content in the buffe > > This design looks good. I have not reviewed the patches in detail but > will review the next revision. > Thanks very much, I'll update it with the recent upstream. :) > Stefan >