Re[3]: parent transid verify failed: Fixed but re-appearing

["Hendrik Friedel" <hendrik@friedels.name>]

Hello Zygo,

can you further me help on this?

Regards,
Hendrik

------ Originalnachricht ------
Von: "Hendrik Friedel" <hendrik@friedels.name>
An: "Zygo Blaxell" <ce3g8jdj@umail.furryterror.org>
Cc: "Btrfs BTRFS" <linux-btrfs@vger.kernel.org>
Gesendet: 22.10.2020 21:30:14
Betreff: Re[2]: parent transid verify failed: Fixed but re-appearing

>Hello Zygo,
>
>thanks for your reply.
>
>>>  [/dev/sda1].generation_errs  1
>>>  [/dev/sdj1].generation_errs  0
>>>  >
>>>  So, on one of the drives only.
>>
>>If one drive is silently dropping writes then it would explain the
>>behavior so far; however, it's relatively rare to have a drive fail
>>that specifically and quietly (and only when you use one particular
>>application).
>Well, we do not know that it occurs when I use one particular application. It could also occur a before and just become visible when using dduper.
>
>>>  > scrub already reports pretty much everything it finds.  'btrfs scrub
>>>  > start -Bd' will present a per-disk error count at the end.
>>>  >
>>>
>>>  So, should I do that now/next?
>>
>>Sure, more scrubs are better.  They are supposed to be run regularly
>>to detect drives going bad.
>btrfs scrub start -Bd /dev/sda1
>
>
>scrub device /dev/sda1 (id 1) done
>         scrub started at Wed Oct 21 23:38:36 2020 and finished after 13:45:29
>         total bytes scrubbed: 6.56TiB with 0 errors
>
>But then again:
>dduper --device /dev/sda1 --dir /srv/dev-disk-by-label-DataPool1/dduper_test/testfiles -r --dry-run
>parent transid verify failed on 16500741947392 wanted 358407 found 358409
>Ignoring transid failure
>
>
>>>  Anything else, I can do?
>>
>>It looks like sda1 might be bad and it is working by replacing lost
>>data from the mirror on sdj.  But this replacement should be happening
>>automatically on read (and definitely on scrub), so you shouldn't ever
>>see the same error twice, but it seems that you do.
>
>Well, it is not the same error twice.
>Both the first ("on") value as well as the following two values change each time.
>What's consistent is, that the wanted vs found always differ by two.
>Here some samples:
>parent transid verify failed on 9332119748608 wanted 204976 found 204978
>parent transid verify failed on 9332147879936 wanted 204979 found 204981
>parent transid verify failed on 16465691033600 wanted 352083 found 352085
>parent transid verify failed on 16500741947392 wanted 358407 found 358409
>
>>That makes it sound more like you've found a kernel bug.
>
>And what do we do in order to narrow it down?
>
>Regards,
>Hendrik
>
>>