6.2 Physical Security
One approach to secure backup is to physically protect backups. If you are an individual user, then you can purchase an external Jaz drive, or a PC card with FLASH memory, copy your sensitive files to the external device, keep it in your possession at all times until you get home, and then bury it ten feet deep in your back yard. Make sure to mark the spot carefully, and to put a mean dog in the yard, preferably one that does not like to dig.
If you are an organization, you could implement a process whereby backups are done under the supervision of security personnel, and the tapes are physically transported to a safe location.
I don't like relying on physical security for several reasons. First of all, it is difficult to find security personnel who are completely trustworthy. Most security compromises are initiated by insiders, and there are few physical security types who are paid as much as the value of your data. Put another way, you'd be crazy to spend more on your security personnel than your data is worth. So, you are potentially vulnerable to bribery of your security personnel.
Physical security is not a bad idea, but I do not recommend relying on it exclusively to protect your data. Instead, couple it with software protection (encryption and authentication).