From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [Qemu-devel] qemu and qemu.git -> Migration + disk stress introduces qcow2 corruptions Date: Sat, 12 Nov 2011 10:01:57 -0600 Message-ID: <4EBE9875.6080505@codemonkey.ws> References: <4EBAAA68.10801@redhat.com> <4EBAACAF.4080407@codemonkey.ws> <4EBAB236.2060409@redhat.com> <4EBAB9FA.3070601@codemonkey.ws> <4EBB919B.7040605@redhat.com> <4EBC1792.3030004@codemonkey.ws> <4EBC4260.1090405@codemonkey.ws> <4EBCF5DA.1000605@redhat.com> <4EBD2B4F.5040409@codemonkey.ws> <4EBE4A02.1070204@redhat.com> <4EBE770A.1080102@codemonkey.ws> <4EBE8623.5040705@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Kevin Wolf , Lucas Meneghel Rodrigues , KVM mailing list , "Michael S. Tsirkin" , "libvir-list@redhat.com" , Marcelo Tosatti , QEMU devel , Juan Jose Quintela Carreira To: Avi Kivity Return-path: Received: from mail-yx0-f174.google.com ([209.85.213.174]:41576 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754348Ab1KLQCC (ORCPT ); Sat, 12 Nov 2011 11:02:02 -0500 Received: by yenr9 with SMTP id r9so4032884yen.19 for ; Sat, 12 Nov 2011 08:02:02 -0800 (PST) In-Reply-To: <4EBE8623.5040705@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 11/12/2011 08:43 AM, Avi Kivity wrote: > On 11/12/2011 03:39 PM, Anthony Liguori wrote: >> On 11/12/2011 04:27 AM, Avi Kivity wrote: >>> On 11/11/2011 04:03 PM, Anthony Liguori wrote: >>>> >>>> I don't view not supporting migration with image formats as a >>>> regression as it's never been a feature we've supported. While there >>>> might be confusion about support around NFS, I think it's always been >>>> clear that image formats cannot be used. >>> >>> Was there ever a statement to that effect? It was never clear to me and >>> I doubt it was clear to anyone. >> >> You literally reviewed a patch who's subject was "block: allow >> migration to work with image files"[1] that explained in gory detail >> what the problem was. >> >> [1] http://mid.gmane.org/4C8CAD7C.5020102@redhat.com >> > > Isn't a patch fixing a problem with migrating image files a statement > that we do support migrating image files? > You know, we could go 9 rounds about this and it really doesn't matter. For 1.0, I feel very strongly that we cannot change the semantics of migration with raw as dramatically as has been proposed. That's a huge regression risk. But since live migration with qcow2 has never worked, there's really not a lot of harm of adding something that makes qcow2 with live migration work better than it does right now. I just sent out a series that does this. It's Kevin's original idea since actually reopening the file doesn't help anything. The only thing that's different from what I expect Kevin would want is that this is restricted to qcow2. I want this restrict for 1.0. If once 1.1 opens up, Kevin wants to promote that code to generic block layer code, that's fine with me. It's also included as part of the migration blockers series so that we are very explicit about when we don't support migration for given image formats. Regards, Anthony Liguori