Plex can't see a subset of files

[amorpheus]

Here is an interesting problem. Some days ago I moved my pooled storage from mhddfs to MergerFS since I've been experiencing a lot of instability with the former and it's only been getting worse. All in all it was very smooth, after checking that everything works I just updated my fstab entry accordingly and it seemed to be running smoothly.

Now I've discovered that on Plex, some of my shows are missing seasons, and they're all on the same disk. But if I open the pooled storage everything is where it should be! I've checked ownership and permissions, they're the same as on the seasons that show up. So the problem is somewhere between MergerFS and Plex, where Plex can't see everything it should even though it shows up fine in the file manager or the command line. What gives?

Being relatively inexperienced with all this, I've tried various mount options and it didn't seem to affect this problem - use_ino, allow_other, cache.files=partial and maybe some more. Any other ideas?

What I'm using are three disks with four partitions, all BTRFS. I've split the 16TB drive into two partitions and those two partitions are actually where files are missing in Plex. Since I'm mounting them as their own drives I didn't expect any complications, does anyone know what is happening here?

[amorpheus]

I've resolved the problem. It wasn't with MergerFS afterall, not directly, but switching brought it to light. After deciding that I can also add all the folders to Plex directly, I realized that Plex doesn't actually see the two partitions I'm having issues with. So I investigated and found the problem pretty easily - permissions. ( https://imgflip.com/i/9l903j )

When I installed the new disk, with the two partitions, something went wrong with the mount points - the permissions were 700 whereas all other disks are 755. This was fine with mhddfs but caused the problem mentioned above in Plex. I don't know why Plex didn't see those files, since it was pointed at the MergerFS pool and not the disks directly. After correcting this discrepancy, everything immediately worked as expected.

Let me know if I should close this, maybe others have some input on why this happened, I'm curious to learn more.

[trapexit]

Glad you figured it out and yes... it's typically permissions.

There is an entry in the FAQ for this very situation.

https://trapexit.github.io/mergerfs/faq/why_isnt_it_working/#why-cant-i-see-my-files-directories

[trapexit]

And yes... mhddfs should not be used by people: https://trapexit.github.io/mergerfs/project_comparisons/#mhddfs

[amorpheus]

That's interesting, I wish I had known that sooner - I set my server up around 2020.

Thanks for the input! As far as I recall, Plex uses its own user, so now this is completely explained.

[trapexit]

Plex isn't special. Software runs as the user/group you define it to run as. Containers may setup some specific uid rather than root but any good image is configurable.