Comment by toast0
If you want 100TB, you need a bigger NAS than most, and that makes most of the DIY NAS not so good. 2-4 drives seems to be where DIY shines. These days motherboards often stop at 4x sata, so you'll need a HBA or USB (eww).
Personally, I just don't have that much data, 24TB mirrored for important data is probably enough, and I have my old mirror set avaialable for media like recorded tv and maybe dvds and blu-rays if I can figure out a way to play them that I like better than just putting the discs in the machine.
We run 48TB (after redundancy, 3 striped mirrors) over a USB enclosure (TerraMaster D6-320) and it's honestly not as bad as people say. The only failure this system experienced in the past few years was due to noisy power causing a reset, and the ZFS root (not the data pool) becoming read only due to a write hole caused by a consumer NVMe (Crucial P3 Plus) lying about being synced (who could've expected that).