I'm using rsync for hdd backups as I run linux 99.9% of the time.
On a laptop so no raid available.
I always take my laptop with me so my backup drive is the one that stays home, so the only time I'm not covered is the times when I might leave the house for a short time and not take the laptop.
I'm thinking of something similar to the GFS tape rotation where my local hdd backup is the daily incrementals, then write important stuff to DVD monthly and then stuff I move to an archive folder just do yearly and back that up afterward. Each dvd I'll make two copies and keep on in my safe and one in the remote location.