I like to keep multiple backups of my files. Backups of backups if you will. I have a few terabytes of data sitting my external drives. In particular, the “main” drive contains files I work with everyday. The data on that drive is ten times more important to me than my MacBook Air. The truth of the matter is, simple backup solution like Time Machine (Mac only) is not available for external drives so I had to look for alternatives.