Re: fs unreadable after powercycle: BTRFS (device sda): parent transid verify failed on 427084513280 wanted 390924 found 390922

[Qu Wenruo]

Martin Tippmann wrote on 2015/08/08 20:43 +0200:
Hi, after a hard reboot (powercycle) a btrfs volume did not come up again:

It's a single 4TB disk - only btrfs with lzo - data=single,metadata=dup

[  121.831814] BTRFS info (device sda): disk space caching is enabled
[  121.857820] BTRFS (device sda): parent transid verify failed on
427084513280 wanted 390924 found 390922
[  121.861607] BTRFS (device sda): parent transid verify failed on
427084513280 wanted 390924 found 390922
[  121.861715] BTRFS: failed to read tree root on sda
[  121.878111] BTRFS: open_ctree failed

btrfs-progs v4.0
Kernel: 4.1.4

I'm quite sure that the HDD is fine (no SMART Problems, Disk Errorlog
is empty, It's a new Enterprise-Drive that worked well in the past
days/weeks).

So I'm kind at loss what to do:

How can I recover from that problem? I've found just a note in the
FAQ[1] but no solution to the problem.

Maybe someone can give some clues why does this happen in the first
place? Is it unfortunate timing due to the abrupt power cycle?
Shouldn't CoW protect against this somewhat?

Thanks for any hints!

Additional info:

# btrfs check /dev/sda
parent transid verify failed on 427084513280 wanted 390924 found 390922
parent transid verify failed on 427084513280 wanted 390924 found 390922
parent transid verify failed on 427084513280 wanted 390924 found 390922
parent transid verify failed on 427084513280 wanted 390924 found 390922
Ignoring transid failure
Couldn't setup extent tree
Seems extent tree or tree root is corrupted.

Couldn't open file system

Not sure what it does but it looks not too good:

# btrfs-find-root /dev/sda
parent transid verify failed on 427084513280 wanted 390924 found 390922
parent transid verify failed on 427084513280 wanted 390924 found 390922
parent transid verify failed on 427084513280 wanted 390924 found 390922
parent transid verify failed on 427084513280 wanted 390924 found 390922
Ignoring transid failure
Couldn't setup extent tree
Couldn't setup device tree
Superblock thinks the generation is 390924
Superblock thinks the level is 1
   Well block 427084988416(gen: 390923 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 427084021760(gen: 390923 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
These two block seems to be good, but not sure why there will be two of 
them.

Try "btrfsck --tree-root 427084988416" and "btrfsck --tree-root 
427084021760" to see which produce the least number of error.

Thanks,
Qu
Well block 427084431360(gen: 390915 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 427084398592(gen: 390915 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 427083988992(gen: 390915 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 427038621696(gen: 390914 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 427031035904(gen: 390913 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 427285069824(gen: 390912 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 427060887552(gen: 390912 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 427013128192(gen: 390912 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 427001872384(gen: 390909 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426965237760(gen: 390906 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426965221376(gen: 390906 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426965188608(gen: 390906 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426965172224(gen: 390906 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426965155840(gen: 390906 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426964271104(gen: 390906 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426964156416(gen: 390906 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426950377472(gen: 390905 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426944512000(gen: 390905 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426940841984(gen: 390905 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426940612608(gen: 390905 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426940465152(gen: 390905 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426940153856(gen: 390905 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426939809792(gen: 390905 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426939711488(gen: 390905 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426939465728(gen: 390905 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426939351040(gen: 390905 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426939006976(gen: 390905 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426938564608(gen: 390905 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426938351616(gen: 390905 level: 0) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 426347577344(gen: 390904 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 168491106304(gen: 390903 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 1340608053248(gen: 390902 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 1340295020544(gen: 390902 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 1264696688640(gen: 390902 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 1136507092992(gen: 390902 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 1136226516992(gen: 390902 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 998473711616(gen: 390902 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 998114721792(gen: 390902 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 667127316480(gen: 390902 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 667048116224(gen: 390902 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 667041382400(gen: 390902 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 667034255360(gen: 390902 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 667028701184(gen: 390902 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 667018526720(gen: 390902 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 666950320128(gen: 390902 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 23074570240(gen: 390902 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 22614048768(gen: 390813 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 22605398016(gen: 390812 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 22599712768(gen: 390811 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 22586949632(gen: 390809 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 1340463906816(gen: 390808 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 1340435660800(gen: 390808 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 1340394799104(gen: 390808 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 1264894115840(gen: 390808 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 1136142614528(gen: 390808 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 666915078144(gen: 390808 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1
Well block 666902560768(gen: 390808 level: 1) seems good, but
generation/level doesn't match, want gen: 390924 level: 1


regards
Martin


1: 
https://btrfs.wiki.kernel.org/index.php/Problem_FAQ#parent_transid_verify_failed
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