From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53321) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XPAM7-0005YZ-PP for qemu-devel@nongnu.org; Wed, 03 Sep 2014 09:12:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XPAM1-0008Ji-CK for qemu-devel@nongnu.org; Wed, 03 Sep 2014 09:12:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:63584) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XPAM1-0008JX-2r for qemu-devel@nongnu.org; Wed, 03 Sep 2014 09:12:05 -0400 Date: Wed, 3 Sep 2014 14:11:59 +0100 From: Stefan Hajnoczi Message-ID: <20140903131159.GM28095@stefanha-thinkpad.redhat.com> References: <20140829172218.GD16755@irqsave.net> <20140902092510.GC29067@stefanha-thinkpad.redhat.com> <54065EE7.4080601@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Kc9HNjpzOXVc7FFU" Content-Disposition: inline In-Reply-To: <54065EE7.4080601@redhat.com> Subject: Re: [Qemu-devel] tcmu-runner and QEMU List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Andy Grover Cc: =?iso-8859-1?Q?Beno=EEt?= Canet , kwolf@redhat.com, qemu-devel@nongnu.org, pbonzini@redhat.com --Kc9HNjpzOXVc7FFU Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Sep 02, 2014 at 05:20:55PM -0700, Andy Grover wrote: > On 09/02/2014 02:25 AM, Stefan Hajnoczi wrote: > > The qemu-lio tool would live in the QEMU codebase and reuse all the > > infrastructure. For example, it could include a QMP monitor just like > > the one you are adding to qemu-nbd. >=20 > Benoit and I talked a little about QMP on another part of the thread... I > said I didn't think we needed a QMP monitor in qemu-lio-tcmu, but let me > spin up on qemu a little more and I'll be able to speak more intelligentl= y. The QEMU block layer has useful features that are available as QMP commands: For example, the drive-mirror QMP command copies a disk image to a new location while still servicing I/O requests. This is used when an administrator needs to migrate disk images to a new file system or storage devices without downtime. There are other commands for snapshots and backup which are issued via QMP. It might even make sense to make the tcmu interface available at run-time in QEMU like the run-time NBD server. This allows you to get at read-only point-in-time snapshots while the guest is accessing the disk. See the nbd-server-start command in qapi/block.json. Stefan --Kc9HNjpzOXVc7FFU Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJUBxOfAAoJEJykq7OBq3PIItgH/2bIYcmdRqZLyobWNokfVB/o zNvnUomyePO6Qg8ONy3DrYVI4+JBAx81kGjPHKb79lZUWdui4xB/fVA5ZHSWuUIQ Gi2hs6wAuvE+0IMZm6P9iisCoVqlDL71Wne4Lf6Xg3gg8Ey9YQmeD3chsbcrBxe9 qC3TI8CqPtZxm6vhMEVfs5666PPK19kP8ZVoUl/u2kL/9+QWqb9kyFJ9adt5jlmZ 8wEcfA1R768MdeLvp8PshGJrK83TGvIas9F1k8law28wlU2893aRB9fvOpOskeep A9gXY2tf4jDqEey2eZ5w4hJdWFp3H73Ubbx/JanvQd9hGkui6CipfohPF8cTC/w= =hcKe -----END PGP SIGNATURE----- --Kc9HNjpzOXVc7FFU--