Re: machine gets unresponsive during btrfs balance

[Andreas Philipp <philipp.andreas@gmail.com>]

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On 26.08.2010 15:27, Johannes Hirte wrote:
> On Saturday 14 August 2010 00:11:55 Andreas Philipp wrote:
>> On 12.08.2010 10:04, Yan, Zheng wrote:
>>> On Thu, Aug 12, 2010 at 3:14 PM, Andreas Philipp
>>> <philipp.andreas@gmail.com> wrote:
>>>   
>>>> Hi,
>>>>
>>>> I am using a btrfs filesystem created with raid0 for data and metadata
>>>> for (temporary) storage of tv recordings from my vdr. The filesystem was
>>>> created under kernel version 2.6.34. An initial btrfs balance command
>>>> succeeded. Since I upgraded to 2.6.35-rcX and 2.6.35 btrfs balance no
>>>> longer finishes but puts the machine in some unresponsive state.
>>>> Unfortunately, I do not see any kernel oops or other debug information
>>>> because even the display freezes. The last thing that happens are that
>>>> those two lines are written to /var/log/messages:
>>>> Aug 11 21:42:23 thor kernel: btrfs: found 62911 extents
>>>> Aug 11 21:42:24 thor kernel: btrfs: relocating block group 1723913469952
>>>> flags 9
>>>> After that the machine becomes immediately unresponsive.
>>>>
>>>> As I did not see anything that might be related to my problem in the
>>>> changelog for 2.6.35.1 I did not try again with this version.
>>>>
>>>>     
>>> Do you have more than one machines? would you please setup netconsole
>>> to see what happen.
>>>   
>> I have reproduced the error on v2.6.35.1 and recorded all kernel output
>> with netconsole. The interesting point is that this time the machine did
>> not crash but the btrfs balance segfaulted at exact the same position
>> where the previous crashes had happened.
> 
> Looks like another manifestation of the csum bug. Are you able to read all 
> files from the affected volume? Did you tried a balance with an 2.6.34 kernel 
> after the test with 2.6.35?
> 
Till now I did not see any unreadable files but I did not do a
complete test. No, I did not try to balance with an 2.6.34 kernel. If
it helps I can switch back and try.

Yours,
Andreas
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