On Fri, Oct 19, 2012 at 2:55 PM, Guido Winkelmann
<[email protected]> wrote:
> Am Donnerstag, 18. Oktober 2012, 18:05:39 schrieb Avi Kivity:
>> On 10/18/2012 05:50 PM, Guido Winkelmann wrote:
>> > Am Mittwoch, 17. Oktober 2012, 13:25:45 schrieb Brian Jackson:
>> >> On Wednesday, October 17, 2012 10:45:14 AM Guido Winkelmann wrote:
>> >> > vda1, logical block 1858771
>> >> > Oct 17 17:12:04 localhost kernel: [ 212.070600] Buffer I/O error on
>> >> > device
>> >> > vda1, logical block 1858772
>> >> > Oct 17 17:12:04 localhost kernel: [ 212.070602] Buffer I/O error on
>> >> > device
>> >> > vda1, logical block 1858773
>> >> > Oct 17 17:12:04 localhost kernel: [ 212.070605] Buffer I/O error on
>> >> > device
>> >> > vda1, logical block 1858774
>> >> > Oct 17 17:12:04 localhost kernel: [ 212.070607] Buffer I/O error on
>> >> > device
>> >> > vda1, logical block 1858775
>> >> > Oct 17 17:12:04 localhost kernel: [ 212.070610] Buffer I/O error on
>> >> > device
>> >> > vda1, logical block 1858776
>> >> > Oct 17 17:12:04 localhost kernel: [ 212.070612] Buffer I/O error on
>> >> > device
>> >> > vda1, logical block 1858777
>> >> > Oct 17 17:12:04 localhost kernel: [ 212.070615] Buffer I/O error on
>> >> > device
>> >> > vda1, logical block 1858778
>> >> > Oct 17 17:12:04 localhost kernel: [ 212.070617] Buffer I/O error on
>> >> > device
>> >> > vda1, logical block 1858779
>> >> >
>> >> > (I was writing a large file at the time, to make sure I actually catch
>> >> > I/O
>> >> > errors as they happen)
>> >>
>> >> What about newer versions of qemu/kvm? But of course if those work, your
>> >> next task is going to be git bisect it or file a bug with your distro
>> >> that
>> >> is using an ancient version of qemu/kvm.
>> >
>> > I've just upgraded both hosts to qemu-kvm 1.2.0
>> > (qemu-1.2.0-14.fc17.x86_64,
>> > built from spec files under http://pkgs.fedoraproject.org/cgit/qemu.git/).
>> >
>> > The bug is still there.
>>
>> If you let the guest go idle (no I/O), then migrate it, then restart the
>> I/O, do the errors show?
>
> Just tested - yes, they do.
The -EIO error does not really reveal why there is a problem. You can
use SystemTap probes in QEMU to find out more about the nature of the
error.
# stap -e 'probe qemu.kvm.bdrv_*, qemu.kvm.virtio_blk_*,
qemu.kvm.paio_* { printf("%s(%s)\n", probefunc(), $$parms) }' -x
$PID_OF_QEMU
Output looks like this:
bdrv_co_readv($arg1=0x7fb2397cc580 $arg2=0x80c $arg3=0x1)
bdrv_co_io_em($arg1=0x7fb2397cc580 $arg2=0x80c $arg3=0x1 $arg4=0x0
$arg5=0x7fb239da6f60)
virtio_blk_rw_complete($arg1=0x7fb23982ed10 $arg2=0x0)
virtio_blk_req_complete($arg1=0x7fb23982ed10 $arg2=0x0)
virtio_blk_rw_complete $arg2=-5 means -EIO so look for that that.
This will reveal what is happening when the error occurs.
Stefan
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