From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MtIQS-0002CM-BG for qemu-devel@nongnu.org; Thu, 01 Oct 2009 05:58:16 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MtIQN-00028J-C1 for qemu-devel@nongnu.org; Thu, 01 Oct 2009 05:58:15 -0400 Received: from [199.232.76.173] (port=41062 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MtIQN-000280-3z for qemu-devel@nongnu.org; Thu, 01 Oct 2009 05:58:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:13729) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MtIQM-00009U-JT for qemu-devel@nongnu.org; Thu, 01 Oct 2009 05:58:10 -0400 Message-ID: <4AC47CEE.1000405@redhat.com> Date: Thu, 01 Oct 2009 11:57:02 +0200 From: Kevin Wolf MIME-Version: 1.0 Subject: Re: [Qemu-devel] qemu-img needs "-O host_device" describing References: <20090930212736.GA17077@ash.smop.co.uk> In-Reply-To: <20090930212736.GA17077@ash.smop.co.uk> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: adrian@smop.co.uk Cc: qemu-devel@nongnu.org Am 30.09.2009 23:27, schrieb Adrian Bridgett: > I've been trying to convert some personal KVM qemu (raw) file images > to raw LVs using kvm-img -O raw. There's a short version and long > version of this tale. > > The short version is "here is a patch to add '-O host_device' to the > manpage", perhaps we should also warn if "kvm-img convert -O raw" is > used on a block device (or even just automatically use host_device?) > > The long version is that first of all I changed block/raw-posix.c so > that it didn't try and ftruncat() block devices and then eventually > tracked down why "kvm-img convert -O raw" fails to block devices (it > seeks past holes effectively which is good on files, but not block > devices). What is the result of this patch? Will raw instead of host_device work without an error message for devices? If so, I'm against the change. It's dangerous: qemu-img would leave zero blocks unchanged instead of overwriting them with zeros, silently corrupting the converted data. > Digging a bit deeper I found reference to "host_device" type and it > turns out that using that as an output format fixes both these issues > - with only one buglet - a hopefully irrelevant error: > > kvm-img convert -O host_device /var/lib/vm/bishop-disk /dev/rootvg/bishop-disk > Unknown option 'size' Yes, this is a bug in the host_device definition. I'll send a fix. Your documentation fix looks fine. Can you resubmit it in a new (top-level) mail with [PATCH] in its subject and a Signed-off-by line in it? Only this way the maintainers will pick it up. Kevin