I've got a lot of those when creating a new ext4 partition on a 4TB HDD (boy, that take some time), and the errors was pilling up.
I will update omv and come back with an edit. (Running 4.1.4-1)
Hi guys, sorry if this thread is a little old, but it's the exact same problem I had.
I found out after my transmission stopped all downloads because of "no space available" that Plex was using /var/lib/plexmediaserver instead the mergerfs directory.
I tried to put outside the mergerfs also, but it started give me (error=255) when launching the pms binary with "service plexmediaserver start"
(The line with "/bin/sh -c ..." in the systemd file.)
Since i "had" to do a clean install uppon a lost of one of my drives, I will try again later today or tomorrow and edit this post.
I was almost going to virtualbox since this is the most problematic package ever, but I'm afraid of transcoding performance.
Greetings from Rio, Brazil.
I'll be back