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From: Thomas Kuther <tom@kuther.net>
To: linux-btrfs@vger.kernel.org
Subject: Qemu disk images on BTRFS suffer checksum errors
Date: Mon, 08 Jul 2013 10:08:46 +0200	[thread overview]
Message-ID: <c48018584d78271b5958df996a72207f@kuther.net> (raw)

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


             reply	other threads:[~2013-07-08  8:08 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-08  8:08 Thomas Kuther [this message]
2013-07-08 13:20 ` Qemu disk images on BTRFS suffer checksum errors Josef Bacik
2013-07-08 18:45   ` Thomas Kuther

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