nullifying backups

While playing with stickam, I decided to demonstrate how I cook dinner to my huge audience. This involved separating frozen meat patties by banging them on the desk. I stopped this maneuver before completion, because my giant external hard drive, also located on the desk, started to whine. Loudly. After cooking and eating my tasty dinner, I returned to the hard drive. I figured the heads had gotten misaligned. With the power off, I tried tapping it gently. I tried tapping it harder. The whine was still there, and prohibitively loud. I figure the medium is probably compromised but I can use it for storage that can be ephemeral. (Damn it.) Today I turned it on again because my iTunes is setup to download podcasts there, and I needed some fresh podcasts. Hey! Writing data to the disk stopped the whining!
So can I ever rely on this disk again?
[UPDATE] No, I can never rely on this disk again, and I should be punished for entertaining the thought that I could. For that matter, I should never rely on a single point of failure for critical data. Time for me to work on my strongspace setup.