From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm Date: Tue, 25 May 2010 08:54:27 -0500 Message-ID: <4BFBD693.2030108@codemonkey.ws> References: <20100519192222.GD61706@ncolin.muc.de> <4BF5A9D2.5080609@codemonkey.ws> <4BF91937.2070801@redhat.com> <87wrutg4dk.wl%morita.kazutaka@lab.ntt.co.jp> <4BFA5D96.3030603@redhat.com> <4BFA696D.2060606@redhat.com> <4BFAD59E.2010706@codemonkey.ws> <4BFB94D9.5080904@redhat.com> <4BFBCDD9.4070104@codemonkey.ws> <4BFBCFB9.6020104@redhat.com> <4BFBD0C6.9000105@codemonkey.ws> <4BFBD261.9040908@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Christian Brunner , MORITA Kazutaka , Blue Swirl , kvm@vger.kernel.org, qemu-devel@nongnu.org, ceph-devel@vger.kernel.org To: Avi Kivity Return-path: Received: from mail-vw0-f46.google.com ([209.85.212.46]:63918 "EHLO mail-vw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933006Ab0EYNyj (ORCPT ); Tue, 25 May 2010 09:54:39 -0400 In-Reply-To: <4BFBD261.9040908@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 05/25/2010 08:36 AM, Avi Kivity wrote: > > We'd need a kernel-level generic snapshot API for this eventually. > >> or (2) implement BUSE to complement FUSE and CUSE to enable proper >> userspace block devices. > > Likely slow due do lots of copying. Also needs a snapshot API. The kernel could use splice. > (ABUSE was proposed a while ago by Zach). > >> If you want to use a block device within qemu, you almost certainly >> want to be able to manipulate it on the host using standard tools >> (like mount and parted) so it stands to reason that addressing this >> in the kernel makes more sense. > > qemu-nbd also allows this. > > This reasoning also applies to qcow2, btw. I know. Regards, Anthony Liguori