What programs do you recommend for checking the health of an external HD?

[oxband]

I have some old external hard drives. Some are 4, 5 years old. They still work fine. That said, I'd love to know if there was some program which let me check the internals so I know if it's dying. Are there any programs that do that? If so, what?

 

[SaSaSushi]

I'm a longtime user and vocal fan of DriveDX. It will work with USB devices by installing the SAT Smart driver as detailed on their website.