From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:59135) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tbuhv-0000Jv-OI for qemu-devel@nongnu.org; Fri, 23 Nov 2012 09:58:25 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Tbuhq-00081k-2W for qemu-devel@nongnu.org; Fri, 23 Nov 2012 09:58:19 -0500 Received: from mx1.redhat.com ([209.132.183.28]:10428) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tbuhp-00081c-Qc for qemu-devel@nongnu.org; Fri, 23 Nov 2012 09:58:13 -0500 Message-ID: <50AF8F01.9060008@redhat.com> Date: Fri, 23 Nov 2012 15:58:09 +0100 From: Kevin Wolf MIME-Version: 1.0 References: <9574d6cc-30fe-4424-b7e7-d363e2abdba9@mailpro> In-Reply-To: <9574d6cc-30fe-4424-b7e7-d363e2abdba9@mailpro> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] qcow2: slow internal snapshot creation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexandre DERUMIER Cc: Dietmar Maurer , qemu-devel@nongnu.org Am 23.11.2012 15:17, schrieb Alexandre DERUMIER: >>> Preallocation doesn't matter much these days. > > I have done benchmark through nfs on a netapp san, (with directio), > > I got 300 iops without preallocation, and 6000 iops with preallocation .... This doesn't sound right, even for writethrough modes. Can you post more details about your benchmark setup so that this can be reproduced? And does it reproduce with local files as well or only using NFS? Kevin