i mirror all my hard drives to separate external hard drives. actually, they are just bare hard drives that i put in a dock with an esata connection use syncback to see what needs to be backed up. it does the copying for me i don't have a raid setup in my computer, though i have 5.5TB worth of drives. 1 2TB drive, 1 1.5TB drive, and 2x 1TB drives same exact setup for the backup its a little labor intensive to swap out drives, but i backup once a week. although, if i have a fire or break in - everything will be gone.