From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-out.m-online.net ([212.18.0.10]:60420 "EHLO mail-out.m-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751220Ab3GHIIu (ORCPT ); Mon, 8 Jul 2013 04:08:50 -0400 Received: from frontend1.mail.m-online.net (frontend1.mail.intern.m-online.net [192.168.8.180]) by mail-out.m-online.net (Postfix) with ESMTP id 3bpfSJ6b26z3hhWW for ; Mon, 8 Jul 2013 10:08:48 +0200 (CEST) Received: from mail.kuther.net (ppp-46-244-135-46.dynamic.mnet-online.de [46.244.135.46]) by mail.mnet-online.de (Postfix) with ESMTP id 3bpfSJ2Jdfzbbjy for ; Mon, 8 Jul 2013 10:08:48 +0200 (CEST) Received: from kuther.net (kuther.net [192.168.1.2]) by mail.kuther.net (Postfix) with ESMTPSA id A216A1096EE4 for ; Mon, 8 Jul 2013 10:08:46 +0200 (CEST) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Date: Mon, 08 Jul 2013 10:08:46 +0200 From: Thomas Kuther To: linux-btrfs@vger.kernel.org Subject: Qemu disk images on BTRFS suffer checksum errors Message-ID: Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hello, I'm about to migrate from VirtualBox to Qemu+VGA-Passthrough. All my virtual disk images are stored in a BTRFS subvolume on-top of a MDRAID 1. The host runs kernel 3.10, and Qemu 1.5.1. The Testing-VM is a Windows 7 64bit, using a RAW virtio disk with cache=none, same happens for qcow2, though. Using VirtualBox and in the past Vmware workstation I never had issues with corrupted diskimages, but now with Qemu all tries ended up with lots of errors like: [ 4871.863009] BTRFS info (device md10): csum failed ino 687 off 46213922816 csum 3817758510 private 402306600 [ 4872.481013] BTRFS info (device md10): csum failed ino 687 off 46213922816 csum 3817758510 private 402306600 [ 4904.055514] BTRFS info (device md10): csum failed ino 687 off 46213922816 csum 4060166193 private 402306600 [ 4904.748130] BTRFS info (device md10): csum failed ino 687 off 46213922816 csum 4060166193 private 402306600 [ 4904.987540] BTRFS info (device md10): csum failed ino 687 off 46213922816 csum 3817758510 private 402306600 [ 4905.024700] BTRFS info (device md10): csum failed ino 687 off 46213922816 csum 3817758510 private 402306600 [ 4932.497793] BTRFS info (device md10): csum failed ino 687 off 46213922816 csum 4060166193 private 402306600 [ 4932.533634] BTRFS info (device md10): csum failed ino 687 off 46213922816 csum 4060166193 private 402306600 Trying to copy the disk image elsewhere causes I/O errors at some point. I found a thread about the issue (http://comments.gmane.org/gmane.comp.file-systems.btrfs/20538) and also a bug report against Qemu from Josef Bacik describing the exact same problem: https://bugzilla.redhat.com/show_bug.cgi?id=693530 - Josef states it should be fixed since quite a while. Is this a regression in BTRFS, a problem with my setup (md raid1 layer below btrfs), or (still) a bug in Qemu? Would cache=writethrough or writeback be an option with BTRFS? Thanks in advance for any input. Best regards, Thomas