From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:34895) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uc0e5-0000HR-HI for qemu-devel@nongnu.org; Mon, 13 May 2013 17:51:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Uc0e2-0000m5-Sh for qemu-devel@nongnu.org; Mon, 13 May 2013 17:51:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:3788) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uc0e2-0000m0-Ki for qemu-devel@nongnu.org; Mon, 13 May 2013 17:50:58 -0400 Date: Mon, 13 May 2013 22:50:49 +0100 From: "Richard W.M. Jones" Message-ID: <20130513215049.GA13384@redhat.com> References: <20130513214655.GA9846@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130513214655.GA9846@redhat.com> Subject: Re: [Qemu-devel] drive-mirror sync points List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wolfgang Richter Cc: Paolo Bonzini , qemu-devel On Mon, May 13, 2013 at 10:46:55PM +0100, Richard W.M. Jones wrote: > On Mon, May 13, 2013 at 01:50:00PM -0400, Wolfgang Richter wrote: > > Paolo/anyone who knows - > > > > Are drive-mirror sync points (NBD flush commands) reflecting guest write > > barriers? Are guest write barriers respected by drive-mirror? If so, that > > would make drive-mirror much more palatable for disk introspection work (a > > drop-in usable feature of QEMU!). > > I'm also interested in this question. Further extensions to this > (*not* drive-mirror on its own AIUI) which stefanha is working on > should allow libguestfs to perform point-in-time snapshots of images, > which will mean that we can do complex and long-running inspection > operations on live guests. OK, I got my attributions wrong there. I see that Dietmar Maurer wrote the original version of the patch and Stefan modified that. Anyway I'm very interested in point-in-time snapshots. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming blog: http://rwmj.wordpress.com Fedora now supports 80 OCaml packages (the OPEN alternative to F#)