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A few days ago my btrfs raid56 filesystem was suddenly mounted read-only. Smartctl -all returned nothing but an error for one of the disks and after replacing the sata-cable the disk now shows its data in smartctl.

However, the filesystem keeps mounting as read-only. When mounting with -o ro, recovery is get the following log in dmesg. The btrfs wiki suggests btrfs check --repair only as a last resort, and suggests trying btrfs scrub first, but it appears this function is broken, potentially corrupting data.

I am not quite sure how to proceed from here. This is not a production server, but I would like to keep my data if possible.

Apr 16 14:17:36 koko kernel: [ 6878.450516] BTRFS info (device sdc1): enabling auto recovery
Apr 16 14:17:36 koko kernel: [ 6878.450521] BTRFS info (device sdc1): disk space caching is enabled
Apr 16 14:17:36 koko kernel: [ 6878.450522] BTRFS: has skinny extents
Apr 16 14:17:37 koko kernel: [ 6878.723995] BTRFS info (device sdc1): bdev /dev/sdd1 errs: wr 720, rd 24652, flush 352, corrupt 0, gen 0
Apr 16 14:17:38 koko kernel: [ 6880.269401] BTRFS error (device sdc1): parent transid verify failed on 16607578931200 wanted 503865 found 503287
Apr 16 14:17:47 koko kernel: [ 6889.021101] BTRFS error (device sdc1): parent transid verify failed on 16607602507776 wanted 503867 found 503290
Apr 16 14:17:47 koko kernel: [ 6889.059511] BTRFS error (device sdc1): parent transid verify failed on 16607620874240 wanted 503866 found 503292
Apr 16 14:17:56 koko kernel: [ 6897.737864] BTRFS error (device sdc1): parent transid verify failed on 16607646154752 wanted 503868 found 503289
Apr 16 14:17:58 koko kernel: [ 6899.606714] BTRFS error (device sdc1): parent transid verify failed on 16607295979520 wanted 503804 found 503267
Apr 16 14:17:58 koko kernel: [ 6900.474443] BTRFS error (device sdc1): parent transid verify failed on 16607651201024 wanted 503868 found 503294
Apr 16 14:17:58 koko kernel: [ 6900.536918] BTRFS error (device sdc1): parent transid verify failed on 16607652282368 wanted 503868 found 503295
Apr 16 14:17:59 koko kernel: [ 6900.868736] BTRFS error (device sdc1): parent transid verify failed on 17377018511360 wanted 503973 found 503336
Apr 16 14:17:59 koko kernel: [ 6900.962038] BTRFS error (device sdc1): parent transid verify failed on 16607295963136 wanted 503804 found 503267
Apr 16 14:18:02 koko kernel: [ 6904.225244] BTRFS error (device sdc1): parent transid verify failed on 16607294504960 wanted 503804 found 503267
Apr 16 14:18:02 koko kernel: [ 6904.256422] BTRFS error (device sdc1): parent transid verify failed on 16607227838464 wanted 503804 found 503800
Apr 16 14:18:07 koko kernel: [ 6909.483754] BTRFS error (device sdc1): parent transid verify failed on 17377217789952 wanted 503988 found 503357
Apr 16 14:18:10 koko kernel: [ 6912.488800] BTRFS error (device sdc1): parent transid verify failed on 17376771735552 wanted 503958 found 503317
Apr 16 14:18:12 koko kernel: [ 6913.713415] BTRFS error (device sdc1): parent transid verify failed on 16607348408320 wanted 503806 found 503270
Apr 16 14:18:17 koko kernel: [ 6919.070038] BTRFS error (device sdc1): parent transid verify failed on 16607767625728 wanted 503924 found 503297
Apr 16 14:18:21 koko kernel: [ 6922.703875] BTRFS error (device sdc1): parent transid verify failed on 16607588286464 wanted 503868 found 503289
  • Run fsck repair experiments on overlay only raid.wiki.kernel.org/index.php/… - note I don't know how well this works with btrfs in particular, as it might go looking for its disks on its own accord and not stick to the overlay. – frostschutz Apr 16 '17 at 13:49

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