Hi, I have hardrives before and they last 3 yers how long will the My Book last if i by. If I by the 20GB one.
Not long … you’ll fill it up in a couple of days 
But seriously, that’s a Crystal Ball ball question … no one will be able to tell you how long it will last.
It could last 1 Year, or 10 Years … no one can predict the future.
That’s not very long … i own several hard drives that are 10 Years and older , and they all still work fine.
I bought my WD MyBook back in 2015 … 6 Years old, and still works Great 
