Backups You'll Actually Test: The 3-2-1 Rule

An untested backup is not a backup. It's a hope with a filename.

3-2-1, plainly

Three copies of anything you care about, on two different kinds of media, with one copy off-site. It's old advice because it keeps being right.

The part everyone skips is the test. Once a quarter I restore something at random and confirm it actually comes back. It's ten boring minutes that have twice turned a disaster into a non-event.