From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Wolf Subject: Re: [Qemu-devel] Re: KVM call minutes for June 8 Date: Thu, 10 Jun 2010 15:08:02 +0200 Message-ID: <4C10E3B2.9070905@redhat.com> References: <20100608150500.GA28492@x200.localdomain> <4C0E694F.8040607@codemonkey.ws> <20100608175952.5f43ea8f@redhat.com> <4C0EB281.80907@codemonkey.ws> <20100609121820.1f3bb47a@redhat.com> <20100609153107.GE28326@redhat.com> <4C0FBFDF.5050009@codemonkey.ws> <4C10B3AF.5000201@redhat.com> <4C10E064.5090106@codemonkey.ws> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "Daniel P. Berrange" , Chris Wright , kvm-devel , armbru@redhat.com, qemu-devel@nongnu.org, Luiz Capitulino To: Anthony Liguori Return-path: Received: from mx1.redhat.com ([209.132.183.28]:21987 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750937Ab0FJNI1 (ORCPT ); Thu, 10 Jun 2010 09:08:27 -0400 In-Reply-To: <4C10E064.5090106@codemonkey.ws> Sender: kvm-owner@vger.kernel.org List-ID: Am 10.06.2010 14:53, schrieb Anthony Liguori: > On 06/10/2010 04:43 AM, Kevin Wolf wrote: >> >> Huh, why this? Seems I still haven't understood all of qcow2 then... I >> always thought that there's just a specific offset where VM state >> starts, but no explicit end. >> > > A live snapshot can last for a very long time. What happens if you need > to allocate a new block for disk I/O while saving a snapshot? You allocate it, I guess? Note that VM state must be virtually contiguous, but not necessarily physically (virtually = on the virtual hard disk as seen by the guest; physically = in the image file). It's just not seen by the guest because it's saved at a high offset that is after the end of the real disk content, but otherwise it should behave the same as guest data. Kevin