I have a Raspberry Pi 3, and booted it with OpenMediaVault 2.2.1 based on the image "omv_2.2.1_rpi2_rpi3.img.gz" as provided in the download section. I set up LAN, a user, added it to all groups (something I need to restrict a bit later). Now I want to connect it with an harddrive full of movies, however, the drive does not show any directories. The drive ran on a QNAP-412 earlier, is error free and has the ext4 filesystem.
What do I have to do? I am shying away from that button "Create Filesystem" as I do not want to overwrite. Every guide here seems to assume that people only create a new NAS from scratch, however, what about those cases where existing solutions need to be moved over to OpenMediaVault? Looking for additional information in this matter. 
Thanks,
Ampleforth