If you don't ALREADY have a backup of the drive, you're living on borrowed time. In the case of my DJ friends, both drives contain the same songs, videos, and other files.. That way, if one takes a dive, the other remains. And EVENTUALLY, an external drive will die. If your files are extremely valuable, a third backup might be the way to go as well. Personally, I've found external drives to be temperamental and I choose to mount the drive internally instead, if at all possible.

Either way, the backup suggestions still stands.

Hope this helps.