From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Mueller Subject: Re: [PATCH][RFC] Use writeback caching by default with qcow2 Date: Thu, 20 Nov 2008 16:23:19 +0000 (UTC) Message-ID: References: <49247615.6050105@us.ibm.com> <49253403.6060603@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: qemu-devel@nongnu.org To: kvm@vger.kernel.org Return-path: Received: from main.gmane.org ([80.91.229.2]:38697 "EHLO ciao.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752637AbYKTQX2 (ORCPT ); Thu, 20 Nov 2008 11:23:28 -0500 Received: from list by ciao.gmane.org with local (Exim 4.43) id 1L3CJR-0008VK-QO for kvm@vger.kernel.org; Thu, 20 Nov 2008 16:23:25 +0000 Received: from 77-58-232-244.dclient.hispeed.ch ([77.58.232.244]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 20 Nov 2008 16:23:25 +0000 Received: from thomas by 77-58-232-244.dclient.hispeed.ch with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 20 Nov 2008 16:23:25 +0000 Sender: kvm-owner@vger.kernel.org List-ID: >> >> > or contrawise: on the other formats the metadata is updated in the >> > correct order? >> > >> > >> raw is the only format we're sure of. > > With that in mind I converted my qcow2 image to raw, and I'm trying to > use that as a base image to create a new raw (writeable) image: > > #qemu-img create -b vista.raw vista.delta Formatting 'vista.delta', > fmt=raw, backing_file=vista.raw, size=20971520 kB qemu-img: Formatting > or formatting option not supported for file format 'raw' > > Doesn't that seem like a bug? Do people just not use raw images in this > way? you can only use a backing file with qcow2 IMHO. also snapshots (savevm/ loadvm) work only with qcow2. - Thomas