RAID give you in time redundancy, so your system doesn't fail while your working.

Most home users don't need this, it's cheaper and better to sync to a 2nd drive nightly. This gives you a local backup and redundancy, because you can swap to that drive if your first drive fails. If you're doing RAID, you still need a local and offsite backup.

How do you sync nightly? If a file is corrupted or a bit is flipped are you copying over a good copy?

I sync on linux, btrfs lets me take snapshots after each sync. I currently use rsync, but I'm thinking of setting my primary drive to btrfs so I can use btrfs sync.

I used to do this with windows. Yeah, if you have corruption, you copy it, but so does a raid? At least this way your safe from fat finger errors and you have a quick access backup.