My main backup is a Netgear STORA. It has 2 bays for 2 drives. Setup as a RAID1, the 2nd drive mirrors the first drive. The hardware will detect a drive failure and email your email list of the warning. You then have time to replace the failed drive with a new one **hot swappable** (must be the same or more capacity). The mirror is rebuilt and you can continue on without worry. It's portable enough to grab and go in case of an emergency, and also has network capabilities. All data can also be accessed online from any computer with user authentication.
Main point here, you have a chance to avoid disaster, the other features are gravy.
My Bluray backups are backups of the backups.
I recall reading a discussion about consumer vs commercial hard drives. One particular person was saying that he had a drive fail in a RAID5 array. He popped in a new drive, and as the array was rebuilding, drive #2 failed. He subsequently discovered that all drives were the same manufacturer & model. Not sure if mixed manufacturers in an array would help or not. Just remember that if it's plugged in, it's vulnerable to the same fire/lightning strike as the primary.
It's best to keep some of your backups off-site. Depending on the type of disaster you're trying to avoid, the further away they are, the better. If your backup drive is sitting next to your computer, it can be stolen at the same time.
Oh! and CHECK YOUR BACKUPS from time to time. I remember another story about some company that never checked their backups, and discovered that at some point in the past, their tapes could no longer hold data properly. When you've lost your data, it's a bad time to discover your backups don't work.