Redundancy != Backups. As a recovering sys admin, I want to state that fact again and again until it syncs in. The difference is that backups should provide po

Redundancy != Backups. As a recovering sys admin, I want to state that fact again and again until it syncs in. The difference is that backups should provide point-in-time snapshots. Now some of the things you suggest provide some of that (Dropbox has some versioning) and manually copying things to multiple locations effectively makes a snapshot of that thing. Backup systems should do this automatically, on a schedule and comprehensively. It says a lot that the best I've used was time machine and it's not especially powerful. It does however "just work." I've wasted hundreds of hours of my life managing various backup software and they all pretty much sucked. They did however save my bacon a number of times.