Synology BTRFS repair

Repair synology BTRFS volume

btrfs fi show -d
(/dev/mapper/vg1000-lv)

syno_poweroff_task -d

(or: umount /volume1)
(or2: umount /volume1 -f -k)

Check to see if all us unmounted:
df -h

mdadm --stop /dev/vg1000/lv

btrfsck /dev/vg1000/lv

btrfs check --repair /dev/vg1000/lv

btrfs rescue super-recover -v /dev/vg1000/lv

vgchange -ay

e2fsck -nvf -C 0 /dev/vg1000/lv

fsck.ext4 -pvf -C 0 /dev/vg1000/lv

(or: e2fsck -pvf -C 0 /dev/vg1000/lv -C O)
(do not do this: -C fd)

Hey i can not do the btrfs repair couse of that 👍 root@Mediaserver:~# btrfs check --clear-space-cache v2 /dev/vg2/volume_2
Syno caseless feature on.
Clear free space cache v2
parent transid verify failed on 1456623927296 wanted 43243 found 41147
parent transid verify failed on 1456623927296 wanted 43243 found 41147
parent transid verify failed on 1456623927296 wanted 43243 found 41147
parent transid verify failed on 1456623927296 wanted 43243 found 41147
Ignoring transid failure
parent transid verify failed on 2113744257024 wanted 41691 found 38109
parent transid verify failed on 2113744257024 wanted 41691 found 38109
parent transid verify failed on 3351185145856 wanted 42474 found 10785
parent transid verify failed on 3351185145856 wanted 42474 found 10785
leaf parent key incorrect 1456561242112
ERROR: failed to clear free space cache v2: -1
btrfs: transaction.h:41: btrfs_start_transaction: Assertion `!(root->commit_root)' failed.
Aborted (core dumped)
what should i do ? can you help me ?

If btrfs check --repair errors out with "couldn't open RDWR because of unsupported option features", you can try clearing the space cache with btrfs check --clear-space-cache v2 or btrfs check --clear-space-cache v1, and retrying the btrfs check --repair.

YMMV. If you break it, you own the pieces, and by the time you need --repair chances are that it broke beyond repair already :-)

👍 ah!!!!! thanks a lot !

This is an excellent gist. Thank you!

syno_poweroff_task -d

is replaced by this in DSM 7:

sudo synostgvolume --unmount -p volume1

But that shuts down ssh so… working on that.

Hi everyone!

I find this interesting guide for EXT4.

This part could be interesting for unmount

synosetkeyvalue /etc/synoinfo.conf disable_volumes volume1

Just as a quick guide for most synology running on 7.x version and with just one volume with brtfs , jsut run the below commands

unmount forcefully the read only partition

umount -f -k /volume1

clear the cache on brtfs so it can then repair

btrfs check --clear-space-cache v2 /dev/mapper/cachedev_0

#run the repair and wait for it to complete
btrfs check --repair /dev/mapper/cachedev_0

reboot the machine and it should be back in 2 minutes.

reboot

after it has rebooted, execute immediately a data scrub on the volume !

If btrfs check --repair errors out with "couldn't open RDWR because of unsupported option features", you can try clearing the space cache with btrfs check --clear-space-cache v2 or btrfs check --clear-space-cache v1, and retrying the btrfs check --repair.

YMMV. If you break it, you own the pieces, and by the time you need --repair chances are that it broke beyond repair already :-)

I've been battling this issue for literally weeks. Clearing the space caches and doing a repair fixed my issue with no data loss!

Thank you SO much!

Greetings from 2024 with a DS1819+ running DSM 7.2.1-69057 Update 3.
Had some corrupted leaves and managed to get btrfs check /dev/mapper/cachedev_0 running by unmounting via synostgvolume --unmount -p /volume1 as mentioned in this xpenology thread and above. It did not shut down SSH for me.

Additionally, I couldn't run btrfs on /dev/vg1000/lv or /dev/md2, only /dev/mapper/cachedev_0 worked properly for unknown reasons. Good luck to you all.