One of tropes in discussions about computer storage I think is the most annoying: "RAID is not backup". Stop saying it as if it is some profound, complicated insight you hold. It's not, it's plain as day. Of course redundancy is not the same as a separate, immutable copy. Come on.
Latest example: "Simplest is to understand RAID is not a backup" Seagate Barracuda Ramp Weakness on Hacker News.