Many external hard drives fail due to excessive wear on the parts that see the most action: the connection ports. When you need to just check the contents, you plug in the drive, see what it lists in its file menu, then you disconnect it again. As a result, the power cable and the data cable (USB, Firewire, etc) are plugged and unplugged until the contact points break down.
To get the longest life out of a drive that you don’t frequently use, simply connect the drive and make a screen capture of its menu. Now, you have two options:
1. Label the screen capture “Drive 1 Contents” and write a “1” on the outside of the drive so that they correspond. This is a great choice if you aren’t passing the drive along to others, since you’ll have the list on your own computer.
2. Print out the screen capture and tape the printout to the outside of the drive (or the outside of the box in which you keep the drive). This option is best for when drives get passed around from one user to another.
When you actually use the drive and alter its contents, just repeat either of the above to keep your lists up-to-date. Doing so will greatly reduce unnecessary plugging and unplugging, thus extending the lifespan of your drive and its valuable contents.