I Found it! The MiniDNLA Log Level was set to Error. I disabled it an now:
Code
root@openmediavault:~# df -h
Dateisystem Größe Benutzt Verf. Verw% Eingehängt auf
udev 3,7G 0 3,7G 0% /dev
tmpfs 760M 5,4M 755M 1% /run
/dev/sde2 456G 15G 419G 4% /
tmpfs 3,8G 0 3,8G 0% /dev/shm
tmpfs 5,0M 8,0K 5,0M 1% /run/lock
efivarfs 128K 59K 65K 48% /sys/firmware/efi/efivars
tmpfs 3,8G 3,7M 3,8G 1% /tmp
/dev/sde1 511M 148K 511M 1% /boot/efi
/dev/sda 3,7T 1,4T 2,4T 36% /srv/dev-disk-by-uuid-815394b1-4cdf-491c-a749-b3a964369e64
/dev/sdd 4,6T 1,9T 2,7T 41% /srv/dev-disk-by-uuid-5b6687a7-82a6-4107-923a-d17b8311a4a3
overlay 456G 15G 419G 4% /var/lib/docker/overlay2/c2487613335dfee6e430cfb691136ef2515db1991cc718e4427e059f62d247cc/merged
overlay 456G 15G 419G 4% /var/lib/docker/overlay2/c74af4032242de196d5edc91e919f0a3523eac6b86a6180e7c90da70ccc1f83c/merged
overlay 456G 15G 419G 4% /var/lib/docker/overlay2/1c8e23099d3cf391e9aa0ed8af07a07bfafb770418f1ea622da64ce3aaf0eeb2/merged
overlay 456G 15G 419G 4% /var/lib/docker/overlay2/f76624e703390ba896e81348ec56ac1268bca85df9f07f293e612d0d338443f9/merged
overlay 456G 15G 419G 4% /var/lib/docker/overlay2/70f5a71347c0d8352db5fcf9eff03e008c9f73b011a8154fcf21e08e339d7282/merged
overlay 456G 15G 419G 4% /var/lib/docker/overlay2/672f6938555bb8792efab2cd90b896ac52bf3501dba86c1689ad7654cabc521e/merged
overlay 456G 15G 419G 4% /var/lib/docker/overlay2/11b371d549dd507067ef8b875e71df54ac3f17d96b8f257aa05050f6b1794adc/merged
overlay 456G 15G 419G 4% /var/lib/docker/overlay2/34856d3d8735265ae22c07d6e377043b191ddf6a5e8c195a6784d69b31366b44/merged
overlay 456G 15G 419G 4% /var/lib/docker/overlay2/fc556a7c0908e403de52ccdad04bb6f442e6c2e787a18b6a9d1d750252639d5f/merged
overlay 456G 15G 419G 4% /var/lib/docker/overlay2/f69f732c50b50bf9aab24c485832def7a119c419bd0227e8ad592ca4ce710d29/merged
overlay 456G 15G 419G 4% /var/lib/docker/overlay2/d5c5afc2a3d08c21496a734afc18095a6d7e287bac4d45f6cc8e72a4e2867804/merged
overlay 456G 15G 419G 4% /var/lib/docker/overlay2/4feb8666886e0c84ee1dc61372ccba8ba23971b08f8573ab98bdaf92023c191b/merged
overlay 456G 15G 419G 4% /var/lib/docker/overlay2/3e2adb8a515394bbc4d4367e8148b0a05030de595bbce056a589ff53b50e9049/merged
root@openmediavault:~#
Display More
Disk use 15G!
Thanks for your help.