I have joined 3 USB disks (sda, sdb and sdc) using the Union Filesystem plugin. The policy used is "Least Free Space" and with 20G of "minimum free space". I have noticed that all the data from my SMB shares or from docker is being saved in sdb until its full, even when I have them pointed to the merged filesystem.
I tried recreating the merged filesystem from scratch but the issue persists.
Any clues?