From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1L36Fv-0003rY-4S for qemu-devel@nongnu.org; Thu, 20 Nov 2008 04:55:23 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1L36Ft-0003qL-EV for qemu-devel@nongnu.org; Thu, 20 Nov 2008 04:55:22 -0500 Received: from [199.232.76.173] (port=55224 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1L36Ft-0003q9-B6 for qemu-devel@nongnu.org; Thu, 20 Nov 2008 04:55:21 -0500 Received: from mx2.redhat.com ([66.187.237.31]:39582) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1L36Fs-0007F9-Rx for qemu-devel@nongnu.org; Thu, 20 Nov 2008 04:55:21 -0500 Message-ID: <49253403.6060603@redhat.com> Date: Thu, 20 Nov 2008 11:55:15 +0200 From: Avi Kivity MIME-Version: 1.0 References: <49247615.6050105@us.ibm.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: [PATCH][RFC] Use writeback caching by default with qcow2 Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Thomas Mueller Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org Thomas Mueller wrote: >> Right now, qcow2 isn't a >> reliable format regardless of the type of cache your using because >> metadata is not updated in the correct order. >> > > so you don't advise to use qcow2 as a VBD or what do you mean with "isn't > reliable"? > Right, qcow2 is both very slow with cache=writethrough (or off), and may corrupt itself if the host crashes at the wrong moment. > or contrawise: on the other formats the metadata is updated in the > correct order? > raw is the only format we're sure of. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.