[Help] repairing Corrupt Volume in TOS 6 using SSH

[Whach]

Hello all!
I have a F4-424 Pro running TOS 6.0.650 with a btrfs file system. All drive bays are populated and a SSD cache is used. It recently experienced a brief power failure and the unit was off. I turned it back on and everything was fine for a couple of hours. All files were present and my plex server was normal and all files/folders were present. It then gave a high temperature warning because of abnormally high CPU usage. So I then rebooted the unit via the web gui. After the reboot, the Volume 1 is corrupted and all files and folders have gone. The storage pool is normal, the disks are green, and the SSD Cache is gone.

I have tried to follow previous posts and posted troubleshooting posts with very little progress, so I am assuming I have done something wrong. I am not that experienced with the command line, so all of this is new to me.

What I have tried so far from guides/posts (assuming that the same TOS 5 commands also apply to TOS 6):

1. SSH using Putty as admin. Used "dmesg" and found multiple instances of red errors:
- "BTRFS error (device dm-0)parent transid verify failed on logical 22864446357504 mirror 1 wanted 370473 found 370501"
- " BTRFS error (device dm-0): open_ctree failed

2. I have used e2fsck -p /dev/mapper/vg0-lv0 command that gave
- "e2fsck: Bad magic number in super-block while trying to open /dev/mapper/vg0-lv0
/dev/mapper/vg0-lv0:
The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem. If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
e2fsck -b 8193 <device>
or
e2fsck -b 32768 <device>"

3. I have used "e2fsck -b 32768 /dev/mapper/vg0-lv0 -y" that gave
- " Bad magic number in super-block while trying to open /dev/mapper/vg0-lv0"

4. Used "btrfs check --repair /dev/mapper/vg0-lv0" that resulted in
- " 10 9 8 7 6 5 4 3 2 1
Starting repair.
Opening filesystem to check...
parent transid verify failed on 22864446357504 wanted 370473 found 370501
parent transid verify failed on 22864446357504 wanted 370473 found 370501
parent transid verify failed on 22864446357504 wanted 370473 found 370501
Ignoring transid failure
Couldn't setup device tree
ERROR: cannot open file system"

Not sure how to proceed from here. Any advice as to how to proceed is appreciated.

[TMzethar]

It is regrettable to hear such news. It appears that the damage to the file system cannot be repaired using the btrfs tool.
If the repair fails, you may consider temporarily mounting it read-only (mount -o ro) to read and copy data or preparing a sufficiently large disk or container to export the data (btrfs restore).
If your power supply environment is unstable, it is recommended that you equip your NAS with an UPS.

[Whach]

The powersupply loss was a rare accident. Are there specific commands/guide tha I can use to repair this? I am not familiar with the command line, and do not know how to apply your read only suggestion. I do not know the correct syntax. Isn't BTRFS supposed to be robust against power outage scenarios? Any help is appreciated. Thanks

[TMzethar]

Please connect to the SSH/Telnet terminal, refer to this:
viewtopic.php?t=2350
If you do not understand how to use these commands, you can contact the technical support team for assistance.

[Whach]

As stated before, I have already been able to connect to it via SSH using Putty. That is not the issue. Can you please provide a working link for customer support?
is [email protected] the correct email address?

[TMzethar]

Yes, that's the email address.

[Whach]

ok. email sent. Let's see what can be done....