RAID is even not an option for several tasks. I for example use Linux
as a real-time DAW, so raid would be much likely counter-productive and
a VM would be completely unusable ;).
Lets stay with backup options that are likely more pleasant for the
averaged desktop user. IMO apart from what I prefer, there are just
rsync based options ok and much likely just without RAID, VMs, tapes and
what soever individual expert solutions.