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Forum Discussion
btrfs _merge_bio_hook error on RN104
Hello,
TL;DR:
Trying to recover from btrfs_merge_bio_hook+a4 error.Managed to boot into tech support mode and connect via telnet but btrfs restore and btrfs check returns "checksum verify failed" message. Ran out of ideas....
Originally posted here
Device details:
- RN104 running 6.5.0 RC1
- RAID5 on 4x4TB
Anyone managed to recover from btrfs_merge_bio_hook+a4 error ..? I tried pretty much everything available and suggested - but no luck. I think there is a bit more, but would be great to get some advice....
What I tried so far:
Boot menu >> normal: got obviously btrfs _merge_bio_hook
Boot menu >> Read only: got the same btrfs _merge_bio_hook
Boot menu >> Tech support:
Managed to connect to device. Here is what I get here:
mdadm -A --scan and then cat /proc/mdstat and it seems like raid was found with the same numbers as before crash. Just one disk seems to be offline
Before crash:
md127 : active raid5 sdd3[0] sda3[3] sdb3[2] sdc3[1]
11706506496 blocks super 1.2 level 5, 64k chunk, algorithm 2 [4/4] [UUUU]After crash:
md127 : active raid5 sdd3[0] sdb3[2] sdc3[1]
11706506496 blocks super 1.2 level 5, 64k chunk, algorithm 2 [4/3] [UUU_]
Before crash
Label: '2fe5571e:RaidNas3' uuid: c763d4aa-2e34-412b-8f91-05b4003019f7 Total devices 1 FS bytes used 8.86TiB devid 1 size 10.90TiB used 8.89TiB path /dev/md127
After crash
# btrfs fi show
Label: '2fe5571e:RaidNas3' uuid: c763d4aa-2e34-412b-8f91-05b4003019f7
Total devices 1 FS bytes used 9.09TiB
devid 1 size 10.90TiB used 9.45TiB path /dev/md127
However - when I tried to mount - I get back to btrfs_merge_bio_hook+a4 error:
# mount -o ro /dev/md127 /mnt/md127 Connection to host lost.
# mount -o recovery,ro /dev/md127 /mnt/md127 Connection to host lost.
# mount -o degraded,ro /dev/md127 /mnt/md127 Connection to host lost.
The btrfs restore and btrfs check are also failing, but without btrfs_merge_bio_hook+a4 error:
# btrfs restore -v /dev/md127 /dev/null checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3 checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3 checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E bytenr mismatch, want=19070892507136, have=6953034540764995676 Couldn't setup extent tree checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3 checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3 checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E bytenr mismatch, want=19070892507136, have=6953034540764995676 Couldn't setup device tree Could not open root, trying backup super checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3 checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3 checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E bytenr mismatch, want=19070892507136, have=6953034540764995676 Couldn't setup extent tree checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3 checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3 checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E bytenr mismatch, want=19070892507136, have=6953034540764995676 Couldn't setup device tree Could not open root, trying backup super checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3 checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3 checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E bytenr mismatch, want=19070892507136, have=6953034540764995676 Couldn't setup extent tree checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3 checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3 checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E bytenr mismatch, want=19070892507136, have=6953034540764995676 Couldn't setup device tree Could not open root, trying backup super # btrfs check --readonly /dev/md127 checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3 checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3 checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E bytenr mismatch, want=19070892507136, have=6953034540764995676 Couldn't setup extent tree Couldn't open file system
The last thing I can think of is to try btrfs restore with -t or -f and point manually to tree or filesystem location, but I'm not sure if details I have from logs copied from the box a few days before the crash got sufficient details:
superblock: bytenr=65536, device=/dev/md127 --------------------------------------------------------- csum 0x23313663 [match] bytenr 65536 flags 0x1 ( WRITTEN ) magic _BHRfS_M [match] fsid c763d4aa-2e34-412b-8f91-05b4003019f7 label 2fe5571e:RaidNas3 generation 28509 root 17129567485952 sys_array_size 129 chunk_root_generation 28505 root_level 1 chunk_root 17129533341696 chunk_root_level 1 log_root 0 log_root_transid 0 log_root_level 0 total_bytes 11987462651904 bytes_used 9738621349888 sectorsize 4096 nodesize 32768 leafsize 32768 stripesize 4096 root_dir 6 num_devices 1 compat_flags 0x0 compat_ro_flags 0x0 incompat_flags 0x21 ( MIXED_BACKREF | BIG_METADATA ) csum_type 0 csum_size 4 cache_generation 18446744073709551615 uuid_tree_generation 28509 dev_item.uuid eb8e7d52-5ec6-4f8c-81e5-aca9487dd115 dev_item.fsid c763d4aa-2e34-412b-8f91-05b4003019f7 [match] dev_item.type 0 dev_item.total_bytes 11987462651904 dev_item.bytes_used 9776486416384 dev_item.io_align 4096 dev_item.io_width 4096 dev_item.sector_size 4096 dev_item.devid 1 dev_item.dev_group 0 dev_item.seek_speed 0 dev_item.bandwidth 0 dev_item.generation 0
Any advice will be more than welcome :)
8 Replies
Replies have been turned off for this discussion
I am in the same boat, Just today went through and was about to run my monthly maintenance on my NAS , it would not respond nor allow me to login to the admin page, ssh, etc.. Chedked front panel and I had the same error, If there is a surefire fix without data loss, I would love to know.
If you put your device back in techsupport mode and private message me your port number, I will see if I can get btrfs restore to work in your case.
Hello. I PMd you yesterday.
Did anyone manage to get this resolved without a FR?
It popped up on me this afternoon -- again, after routine maintenance (as another post mentions)
- Not that I'm aware of but I was given some info, if there were a way to SSH into the nas I would recover only the data I need and then dump the rest. But I'm not given proper info on how to enable SSH
Sliquid wrote:
Not that I'm aware of but I was given some info, if there were a way to SSH into the nas I would recover only the data I need and then dump the rest. But I'm not given proper info on how to enable SSHI can get in through recovery / telnet.
But, the moment I try to mount md127, everything goes kaput with the btrfs_merge_bio_hook error.
I've tried the btrfs recovery things in here with no avail as well.
And, like this post, it's saying that one of my disks is missing, when it's clearly in it's spot.
If I remove one of the disks, I'd expect it to drop to degredated mode, but it boots completely and says I have New disks in the web interface.
SmplyUnprdctble wrote:
Sliquid wrote:
Not that I'm aware of but I was given some info, if there were a way to SSH into the nas I would recover only the data I need and then dump the rest. But I'm not given proper info on how to enable SSHI can get in through recovery / telnet.
But, the moment I try to mount md127, everything goes kaput with the btrfs_merge_bio_hook error.
I've tried the btrfs recovery things in here with no avail as well.
And, like this post, it's saying that one of my disks is missing, when it's clearly in it's spot.
If I remove one of the disks, I'd expect it to drop to degredated mode, but it boots completely and says I have New disks in the web interface.
PM me your port number and I'll glance at it.
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