I'm still using the simple "roll my own" setup with mhddfs across a bunch of very large drives, with a second set of very large drives to which I periodically mirror the first set.

mhddfs does the same kind of thing as Unraid, spreading the files around evenly, and a single drive failure loses data only on that single drive. The backup array ensures I always have a complete backup, can recover anything, and without suffering long RAID-style parity rebuilds.

Either of those two methods (Unraid, mhddfs) seem to be the best solutions out there at the moment. But both, like anything else, do NOT eliminate the need for full backups.

Cheers