What is the 3-2-1 rule for backing up your data?

Make sure your files are safe in the event of a hard drive disaster.

Make sure your files are safe in the event of a hard drive disaster.<p><img src="https://www.engadget.com/img/gallery/what-is-the-3-2-1-rule-for-backing-up-your-data/intro-1791388945.jpg" /></p>