From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sylvain Bauza Subject: Re: Win2003 disk corruption with kvm-1.0. and virtio Date: Wed, 13 Feb 2013 10:53:14 +0100 Message-ID: <511B628A.3040005@digimind.com> References: <511A520D.4@digimind.com> <20130213090317.GA12049@stefanha-thinkpad.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: kvm@vger.kernel.org To: Stefan Hajnoczi Return-path: Received: from mail-wg0-f49.google.com ([74.125.82.49]:63708 "EHLO mail-wg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932454Ab3BMJx3 (ORCPT ); Wed, 13 Feb 2013 04:53:29 -0500 Received: by mail-wg0-f49.google.com with SMTP id 15so787890wgd.28 for ; Wed, 13 Feb 2013 01:53:28 -0800 (PST) In-Reply-To: <20130213090317.GA12049@stefanha-thinkpad.redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Hi Stefan, As per documentation, Nova (Openstack Compute layer) is doing a=20 'qemu-img convert -s' against a running instance. http://docs.openstack.org/trunk/openstack-compute/admin/content/creatin= g-images-from-running-instances.html Do you think it could be our root cause ? Btw, I tested cache=3Dwritethrough and I observed image corruption afte= r=20 some time ('qemu-img check' returns errors) Thanks for your input, -Sylvain Le 13/02/2013 10:03, Stefan Hajnoczi a =E9crit : > On Tue, Feb 12, 2013 at 03:30:37PM +0100, Sylvain Bauza wrote: >> We currently run Openstack Essex hosts with KVM-1.0 (Ubuntu 12.04) >> instances with qcow2,virtio,cache=3Dnone >> >> For Linux VMs, no trouble at all but we do observe filesystem >> corruption and inconsistency (missing DLLs, CHKDSK asked by >> EventViewer, failure at reboot) with some of our Windows 2003 SP2 >> 64b images. >> >> At first boot, stress tests (CrystalDiskMark 3.0.2 and intensive >> CHKDSK) don't show up problems. It is only appearing 6 or 12h later. >> >> Do you have any idea on how to prevent it ? Is cache=3Dwritethrough = an >> acceptable solution ? We don't want to leave qcow2 image format as >> it does allow to do live snapshots et al. > How are you taking live snapshots? qemu-img should not be used on a > disk image that is currently open by a running guest, it may lead to > corruption. > > Stefan