@Frank and Surfninja
Thank you oh so much for all the help and advice, but the problem has been solved now
What did I do??
After trying Install Volumio 2.001 on my SD-cart and testing it ( has a beautifull outfit, but not working at all ) I formatted the SD-cart again and intall RuneAudio for the second time.
This time I did not activate Spotify immediately, but I added a network mount to a folder in my old Popcorn Hour using this as NAS.
Then I clicked on "remount all sources" and what you think...Runeaudio perfectly build the library as well from the hdd as the network mount.
Result: only folder containing music are showed in the library just as Volumio 1.55 did and everything is working perfectly.
Then I activated Spotify and this is also working.
Then I discovered something I did not know the first time: Runeaudio is having a small button right under the artistname in the playbackscreen: "Playback source". Here you can switch between MPD ans Spotify.
During my first install it was all the time in the Spotify modus and maybe this was the reason why it did not build the MPD library.
I am not quite sure, but most important is that everything is working now.
Maybe I gonna make a thirth install on a better SD-card and make a better diagnostic.
One thing is sure: also RuneAudio is having no problems when the hhd is containing a lot of other files.
My hdd is containig a lot of Wi- games, Acronis backups and a lot more which have nothing to do with music.
The endresult is only two folders with music.
I am very satisfied with Rune now, but there are two things I will come back for:
1. Activating Samba share, I did read something on this forum allready.
2. How to get the Spotify playlists alphabetic
Why the last?
Spotify has no search option and that is why I add a lot of complete albums as playlist with the spotify app.
It would be very nice if Abba is above and ZZ top below.
Now the latest added are above.
Sorry I will put this in a new topic.
Thanks a lot again