As far as I can tell, the data I copied during that time is not that important. Most stuff that I can regenerate from project-files but it will take time. Most of it were huge cache files.
But I can't tell if I haven't copied some other data in-between. But even than, it wouldn't be that bad.

All important data is on disc 1.

How do I proceed now? Just slot disc 2 back in? Format it and it should work as expected?

And thank you a lot to everyone who tried to help me! You are the best <3

About real back-ups:
Real Back-Ups is also something that is on my to-do list. The problem with the drive through my off my original plans and timing. I plan to buy an external 16TB drive, which will mirror the data on the NAS. At least that was my plan until now.


about cache size:
I think it is just a display thing with the cache size

Edited January 6Jan 6 by Tyrus

If you format disk2, it will be mountable and empty. Then you can write to it. You can even do this while parity check is running.

If you want to use the combined size of the 2 cache drives instead of mirror, you need to reformat the pool using the 'single' profile. But probably should give more specific advice about that after I have looked at how your shares and other things are configured.

If it isn't already, start array in normal (not maintenance) mode and...

Attach Diagnostics ZIP to your NEXT post in this thread.

7 minutes ago, trurl said:

reformat the pool using the 'single' profile

Or maybe you don't have to reformat, just change and rebalance:

https://docs.unraid.net/unraid-os/using-unraid-to/manage-storage/cache-pools/#changing-pool-raid-levels

According to the diagnostics you already posted at the beginning, your shares are configured correctly.

So, fun thing happened yesterday after we talked.
I wanted to go to bed but before that, I assigned the precleared "faulty" disc back to it's slot as disc 2 and it gave me a warning. Bla bla all the data on the disc will be lost, if you start this config and since it was pre-cleaned and the data lost anyway, I just did it. The array went online and started to recover from the parity drive so I went to bed.
Now I come back from work and the drive is restored and also the files!

So I guess the filesystem error happened through the OS update after all and not my parity swap adventures. Or how should I interpret all of this? :D


But one thing bothers me and I noticed it yesterday. Yesterday, when someone asked me to mount the working data drive(disc1) that was not affected, as an unassigned device and check for data, I looked in a particular folder and there were files there.
But after I put the disc back in the array, and access the NAS over the network, and access the same folder this way, there are no files.

So now I put the disc1 back out of the array and mounted it as unassigned, the files show up there. Any Idea what the problem could be? And why they don't show up in the folder over the network?

6 minutes ago, Tyrus said:

if you start this config and since it was pre-cleaned and the data lost anyway, I just did it. The array went online and started to recover from the parity drive so I went to bed.
Now I come back from work and the drive is restored and also the files!

That doesn't make any sense, or the emulated disk should have worked before, unless I'm missing something.

I noticed something yesterday. Before, the disc 2 always showed up as "unmountable: wrong or no file system". When I started the array.
At some point I think I removed it from the array and something happened at this point.

The unassigning from the array seems to have triggered something, so the disc was recognized differently after that.

Edited January 7Jan 7 by Tyrus

On 1/7/2026 at 7:20 PM, Tyrus said:

But one thing bothers me and I noticed it yesterday. Yesterday, when someone asked me to mount the working data drive(disc1) that was not affected, as an unassigned device and check for data, I looked in a particular folder and there were files there.
But after I put the disc back in the array, and access the NAS over the network, and access the same folder this way, there are no files.

So now I put the disc1 back out of the array and mounted it as unassigned, the files show up there. Any Idea what the problem could be? And why they don't show up in the folder over the network?

Has someone any ideas how to fix this problem? The files are there since the size also remains the same but I just can't see them over the network and the folder is just empty.

Edited January 10Jan 10 by Tyrus

On 1/7/2026 at 1:20 PM, Tyrus said:

put the disc1 back out of the array and mounted it as unassigned, the files show up there. Any Idea what the problem could be? And why they don't show up in the folder over the network?

If user shares are broken because some assigned disk is having problems, then you won't be able to see anything in user shares, but the data will still be on the good disks.

Can you start the array in normal mode and post new diagnostics?

It is just one particular folder that is having problems. Can I somehow just reassign/refresh the user shares for this folder?

unraidnas-diagnostics-20260110-1429.zip

16 minutes ago, Tyrus said:

reassign/refresh the user shares

The user shares are created from the top level folders on assigned disks and pools each time the array starts.

17 minutes ago, Tyrus said:

one particular folder

Can you show me a screenshot of that folder from the Unraid File Manager?

Jan 7 18:31:38 UnRaidNAS kernel: XFS (md2p1): Metadata CRC error detected at xfs_dir3_leaf_read_verify+0x7e/0x100, xfs_dir3_leaf1 block 0x4000068

Jan 7 18:31:38 UnRaidNAS kernel: XFS (md2p1): Unmount and run xfs_repair

Check filesystem on disk2

21 hours ago, trurl said:

The user shares are created from the top level folders on assigned disks and pools each time the array starts.

Can you show me a screenshot of that folder from the Unraid File Manager?

Damn, I started the check filesystem now. Anything in particular you are looking for?

2 hours ago, JorgeB said:

Jan 7 18:31:38 UnRaidNAS kernel: XFS (md2p1): Metadata CRC error detected at xfs_dir3_leaf_read_verify+0x7e/0x100, xfs_dir3_leaf1 block 0x4000068

Jan 7 18:31:38 UnRaidNAS kernel: XFS (md2p1): Unmount and run xfs_repair

Check filesystem on disk2

Oh no, not again... But why is it showing up as ok on the ui main tab, if there is was an error detected in the background?

I started a check, will be done in 4-5 hours.

34 minutes ago, Tyrus said:

started a check, will be done in 4-5 hours.

A XFS check normally only takes minutes

3 hours ago, Tyrus said:

Oh no, not again...

Have you done memtest recently?

3 hours ago, itimpi said:

A XFS check normally only takes minutes

For me it always took forever. About the same as a complete parity check. 4-6 Hours. Still going atm.

2 minutes ago, trurl said:

Have you done memtest recently?

Nope, is there a build in tool in Unraid or do I have to use some Linux commands?

memtest is on the boot menu

I fear the XFS check won't work, like it didn't last time. So the check finished. Tried the fix. Fix said:

Phase 1 - find and verify superblock... couldn't verify primary superblock - not enough secondary superblocks with matching geometry !!! attempting to find secondary superblock...

And now it will probably run again for another 4-5 hours. As soon as it finishes I will also do a memtest and report back.

Edited January 11Jan 11 by Tyrus

1 hour ago, Tyrus said:

As soon as it finishes I will also do a memtest

You should do memtest first.

You must not attempt to run any computer unless memory is working perfectly. Everything goes through RAM. The OS and other executable code, your DATA. EVERYTHING. The CPU can't do anything with anything until it is loaded into RAM.

On 1/11/2026 at 7:15 PM, trurl said:

You should do memtest first.

You must not attempt to run any computer unless memory is working perfectly. Everything goes through RAM. The OS and other executable code, your DATA. EVERYTHING. The CPU can't do anything with anything until it is loaded into RAM.

The Memtest ran for over 9 hours and there were no errors.

Here is the screenshot from the folder I am having problems with:

Does this help? The folder contains files from disc 1 and 2 but neither are showing when I access the folder over the network.

Edited January 13Jan 13 by Tyrus

17 minutes ago, Tyrus said:

Here is the screenshot from the folder I am having problems with

Tools - New Permissions on that user share

21 hours ago, trurl said:

Tools - New Permissions on that user share

I noticed the tool, but wasn't sure if it was the correct use case.

Does it make a difference that the folder I am having problems with is a subfolder of a share?

No just don't use New Permissions on appdata

23 hours ago, trurl said:

Tools - New Permissions on that user share

Unfortunately it didn't change anything and finished surprisingly fast. In about 2 Minutes.

What do you get from command line with this?

ls -lah /mnt

and this?

ls -lah /mnt/user

On 1/14/2026 at 10:22 PM, trurl said:

What do you get from command line with this?

ls -lah /mnt

and this?

ls -lah /mnt/user

Are we looking for something particular? A subfolder in "NAS" is having the problem.

root@UnRaidNAS:~# ls -lah /mnt
total 16K
drwxr-xr-x 11 root   root  220 Jan 13 20:33 ./
drwxr-xr-x 20 root   root  420 Jan 13 20:34 ../
drwxrwxrwt  2 nobody users  40 Jan 13 07:58 addons/
drwxrwxrwx  1 nobody users  48 Jan 10 14:29 cache/
drwxrwxrwx  8 nobody users  86 Jan 10 14:29 disk1/
drwxrwxrwx  3 nobody users  17 Jan 10 14:29 disk2/
drwxrwxrwt  2 nobody users  40 Jan 13 07:58 disks/
drwxrwxrwt  2 nobody users  40 Jan 13 07:58 remotes/
drwxrwxrwt  2 nobody users  40 Jan 13 07:58 rootshare/
drwxrwxrwx  1 nobody users  86 Jan 10 14:29 user/
drwxrwxrwx  1 nobody users  86 Jan 10 14:29 user0/
root@UnRaidNAS:~# ls -lah /mnt/user
total 4.0K
drwxrwxrwx  1 nobody users   86 Jan 10 14:29 ./
drwxr-xr-x 11 root   root   220 Jan 13 20:33 ../
drwxrwxrwx  1 nobody users   72 Aug 20 21:15 DEV/
drwxrwxrwx  1 nobody users   21 May 17  2025 Danis/
drwxrwxrwx  1 nobody users 4.0K Jan  7 20:12 NAS/
drwxrwxrwx  1 nobody users  114 Aug  3 17:12 appdata/
drwxrwxrwx  1 nobody users    0 Oct 20  2024 domains/
drwxrwxrwx  1 nobody users    6 Jan  7  2025 gemeinsam/
drwxrwxrwx  1 nobody users   38 Oct 24  2024 isos/
drwxrwxrwx  1 nobody users    6 Jan 19  2025 pictures/
drwxrwxrwx  1 nobody users   26 Oct 20  2024 system/

Edited January 16Jan 16 by Tyrus