After I didn't get any answers in German, I'll try my luck again in English ...
During my new installation I tried the two plugins Union FS and Merger FS.
Unfortunately, I am not getting the result I wanted.
For each of my main directories I would like to specify whether the data is distributed over several disks or specifically stored on one disk.
/Medienspeicher/Bilder/2020 -> All Pictures of 2020
E.g. Photo folders can be distributed, but the whole Photos / 2020 folder.
Music or documents could be placed discreetly on a disk.
I want to user the spin down feature on the disks,
therefore sensible data storage is important.
With UnionFS I couldn't do that, with Merger FS I don't know what to enter in the path.
Can someone help me with this.