What file system for usb-hd?

This question was sort of buried in “Where is my music?” So I thought I’d post it straight up. What fs does Volumio want for a connected usb-hd? Being Linux based, I assumed ext4, but should it be ntfs? fat-32? something else?
Thanks

The answer is FAT-32. Neither ext4 nor ntfs worked well with Volumio, but FAT-32 seems to be functioning just fine. :sunglasses: