1. I'm trying to figure out how to recover my cache drive in Unraid. My server kept crashing every couple weeks, and the RAM failed after running a memtest. After a restart, the cache drive (btrfs) says

   unmountable: wrong or no file system

   , and I found a guide on the forum for this exact issue, but I'm having trouble getting it to work (Internet Archive Link). I went all the way through step 1 and it didn't work, so I started method/step 2 but got an error saying

   /dev/sdb1 is currently mounted, cannot continue

   when attempting to copy the contents off of it, but the cache doesn't say it's mounted in the Main tab of Unraid

   What am I missing?

4 hours ago, DreadPirateRoberts1987 said:

/dev/sdb1 is currently mounted, cannot continue

This means it's already mounted. Browse the temp folder you used; if you followed the FAQ it's /temp

18 hours ago, JorgeB said:

[...] Browse the temp folder you used

I found the /temp folder I created, I should then copy the contents (in this case it's just an /appdata and /docker folder) over to the Array? Then format the cache drive, and move everything back onto it? The guide isn't super clear about what I should do it if works. I set up the server months ago and forgot about how to navigate this for the most part.

7 hours ago, DreadPirateRoberts1987 said:

I should then copy the contents (in this case it's just an /appdata and /docker folder) over to the Array?

Yes, array or another pool/disk.

7 hours ago, DreadPirateRoberts1987 said:

Then format the cache drive, and move everything back onto it?

Yep

15 hours ago, JorgeB said:

Yes, array or another pool/disk.

I was able to move the contents to an external drive, mounted with the unassigned devices plugin. But after formatting the Cache, it still says unmountable, but instead of "wrong", it just says ```Unmountable: no file system```. I tried formatting it again, same result. Does this mean it's an issue with the nvme itself, or is there something else I can do before replacing it?

Try rebooting first, and if the same, post new diags after a format attempt.

After rebooting, I was able to mount the cache drive with the command line, move the folders back onto it, reboot again just in case, then mount it through the GUI. Docker containers were able to load properly, now I'm dealing with a separate issue where the plex server isn't working, I'll make a new thread if I can't solve that on my own, probably just due to all the new hardware I put in the build. Thanks for the assist Jorge!

Edit: I fixed the plex server, I just needed to log in again on the server side using my main account.

Edited November 26, 2025Nov 26 by DreadPirateRoberts1987