I use mergerfs to pool a bunch of varying sized drives and then run snapraid on the whole pool to protect it. Then, I’ve got Kopia backups running and backup up to a remote repository. This solution has been flexible and I’ve already been able to recover from 2 drive failures very quickly and easily.

Purdue University still has a campus-only file sharing network called DTella that’s DC++. It been getting smaller, but there were a few members that shared 50+ TB at one point.