It’s got tons of flexibility to account for a variety of use cases. Ya, it’s something that took me a bit to get my head around too. As for making a share for family members, depending on how much data they have and what drives you have, you might choose to make a share for each user on a disk dedicated to them, or you might make a share for each but put them all on one disk if they don’t need enough space to justify having a disk dedicated to each. You can have that media share span multiple disks and you add disks to the share of you need more space. You could have separate shares for movies, tv shows, etc., or just one for all the media. The last two are a single share for all my media files.
One disk has multiple shares, one for general backups(say backing up software installers), and one to backup my Windows installation. Using my server as an example, I have 5 data disks(plus two for parity) 2 of those disks are assigned to a single share each, one for my iMac Backups, one for all my MacBooks. The best way is whatever makes sense to you for your purposes. From the perspective of someone accessing the share on the network, they just have to access the share, and don’t care which disk resides on because they only see the share’s file tree, not the disks file tree. If you have multiple disks assigned to one share then UnRaid will manage what data is put on each disk, based on the users chosen settings(Such we fill one disk, then the next, or always use the disk with the least space used or most space free). A share can have multiple disks assigned to it and/or you can assign multiple shares to a disk. A disk share simply shares an individual disk, with a user share, you assign or exclude disks to/from the share. With UnRaid you can assign user shares or disk shares.