Hi all, there is 1-block corruption a 8TB filesystem that showed up several months ago. The fs is almost exclusively a btrfs receive target and receives monthly sequential snapshots from two hosts but 1 received uuid. I do not know exactly when the corruption has happened but it must have been roughly 3 to 6 months ago. with monthly updated kernel+progs on that host.
Some more history: - fs was created in november 2015 on top of luks - initially bcache between the 2048-sector aligned partition and luks. Some months ago I removed 'the bcache layer' by making sure that cache was clean and then zeroing 8K bytes at start of partition in an isolated situation. Then setting partion offset to 2064 by delete-recreate in gdisk. - in december 2016 there were more scrub errors, but related to the monthly snapshot of december2016. I have removed that snapshot this year and now only this 1-block csum error is the only issue. - brand/type is seagate 8TB SMR. At least since kernel 4.4+ that includes some SMR related changes in the blocklayer this disk works fine with btrfs. - the smartctl values show no error so far but I will run an extended test this week after another btrfs check which did not show any error earlier with the csum fail being there - I have noticed that the board that has the disk attached has been rebooted due to power-failures many times (unreliable power switch and power dips from energy company) and the 150W powersupply is broken and replaced since then. Also due to this, I decided to remove bcache (which has been in write-through and write-around only). Some btrfs inpect-internal exercise shows that the problem is in a directory in the root that contains most of the data and snapshots. But an rsync -c with an identical other clone snapshot shows no difference (no writes to an rw snapshot of that clone). So the fs is still OK as file-level backup, but btrfs replace/balance will fatal error on just this 1 csum error. It looks like that this is not a media/disk error but some HW induced error or SW/kernel issue. Relevant btrfs commands + dmesg info, see below. Any comments on how to fix or handle this without incrementally sending all snapshots to a new fs (6+ TiB of data, assuming this won't fail)? # uname -r 4.11.3-1-default # btrfs --version btrfs-progs v4.10.2+20170406 fs profile is dup for system+meta, single for data # btrfs scrub start /local/smr [27609.626555] BTRFS error (device dm-0): parent transid verify failed on 6350718500864 wanted 23170 found 23076 [27609.685416] BTRFS info (device dm-0): read error corrected: ino 1 off 6350718500864 (dev /dev/mapper/smr sector 11681212672) [27609.685928] BTRFS info (device dm-0): read error corrected: ino 1 off 6350718504960 (dev /dev/mapper/smr sector 11681212680) [27609.686160] BTRFS info (device dm-0): read error corrected: ino 1 off 6350718509056 (dev /dev/mapper/smr sector 11681212688) [27609.687136] BTRFS info (device dm-0): read error corrected: ino 1 off 6350718513152 (dev /dev/mapper/smr sector 11681212696) [37663.606455] BTRFS error (device dm-0): parent transid verify failed on 6350453751808 wanted 23170 found 23075 [37663.685158] BTRFS info (device dm-0): read error corrected: ino 1 off 6350453751808 (dev /dev/mapper/smr sector 11679647008) [37663.685386] BTRFS info (device dm-0): read error corrected: ino 1 off 6350453755904 (dev /dev/mapper/smr sector 11679647016) [37663.685587] BTRFS info (device dm-0): read error corrected: ino 1 off 6350453760000 (dev /dev/mapper/smr sector 11679647024) [37663.685798] BTRFS info (device dm-0): read error corrected: ino 1 off 6350453764096 (dev /dev/mapper/smr sector 11679647032) [43497.234598] BTRFS error (device dm-0): bdev /dev/mapper/smr errs: wr 0, rd 0, flush 0, corrupt 1, gen 0 [43497.234605] BTRFS error (device dm-0): unable to fixup (regular) error at logical 7175413624832 on dev /dev/mapper/smr # < figure out which chunk with help of btrfs py lib > chunk vaddr 7174898057216 type 1 stripe 0 devid 1 offset 6696948727808 length 1073741824 used 1073741824 used_pct 100 chunk vaddr 7175971799040 type 1 stripe 0 devid 1 offset 6698022469632 length 1073741824 used 1073741824 used_pct 100 # btrfs balance start -v -dvrange=7174898057216..7174898057217 /local/smr [74250.913273] BTRFS info (device dm-0): relocating block group 7174898057216 flags data [74255.941105] BTRFS warning (device dm-0): csum failed root -9 ino 257 off 515567616 csum 0x589cb236 expected csum 0xee19bf74 mirror 1 [74255.965804] BTRFS warning (device dm-0): csum failed root -9 ino 257 off 515567616 csum 0x589cb236 expected csum 0xee19bf74 mirror 1 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
