From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juan Quintela Subject: Re: qemu and qemu.git -> Migration + disk stress introduces qcow2 corruptions Date: Wed, 09 Nov 2011 21:57:23 +0100 Message-ID: References: <4EBAAA68.10801@redhat.com> <4EBAACAF.4080407@codemonkey.ws> <4EBAB236.2060409@redhat.com> <4EBAB9FA.3070601@codemonkey.ws> <20111109201836.GA28457@redhat.com> Reply-To: quintela@redhat.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Anthony Liguori , Avi Kivity , Lucas Meneghel Rodrigues , Kevin Wolf , KVM mailing list , Marcelo Tosatti , QEMU devel To: "Michael S. Tsirkin" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:4690 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753513Ab1KIU6s (ORCPT ); Wed, 9 Nov 2011 15:58:48 -0500 In-Reply-To: <20111109201836.GA28457@redhat.com> (Michael S. Tsirkin's message of "Wed, 9 Nov 2011 22:18:37 +0200") Sender: kvm-owner@vger.kernel.org List-ID: "Michael S. Tsirkin" wrote: > On Wed, Nov 09, 2011 at 11:35:54AM -0600, Anthony Liguori wrote: >> On 11/09/2011 11:02 AM, Avi Kivity wrote: >> >On 11/09/2011 06:39 PM, Anthony Liguori wrote: >> >> >> >>Migration with qcow2 is not a supported feature for 1.0. Migration is >> >>only supported with raw images using coherent shared storage[1]. >> >> >> >>[1] NFS is only coherent with close-to-open which right now is not >> >>good enough for migration. >> > >> >Say what? >> >> Due to block format probing, we read at least the first sector of >> the disk during start up. > > A simple solution is not to do any probing before the VM is first > started on the incoming path. > > Any issues with this? hw/pc.c:cmos init of the devices needs to know the geometry. But looking at the code, "perhaps" this commit has made things work correctly even if we open them late. Something like this was the idea that Anthony suggested last time I showed the problem. Later, Juan. commit c0897e0cb94e83ec1098867b81870e4f51f225b9 Author: Markus Armbruster Date: Thu Jun 24 19:58:20 2010 +0200 pc: Fix CMOS info for drives defined with -device