Unless you have a really good reason to use an external drive, there is no good reason to use an external drive LOL. They are much more susceptible to heat related failures than internal drives. If you must have portability, or it is on a laptop, then they are a viable option for storage, but not the best if they are going to be connected and used for long periods of time. Are these the 2.5 inch bus powered drives? or do they have separate power supply? What is the nature of the failure.. Do they still spin? Do they click? Is it just that you cannot get to the files?