One backup is not enough. The 3-2-1 rule is an easy way to remember how many copies to keep and where to put them.

What the numbers mean

The rule has three parts.

  • Keep three copies of your data: the original and two backups
  • Use two different kinds of storage, such as a drive and the cloud
  • Keep one copy somewhere else, away from your office

What it protects against

Different copies guard against different disasters: a failed drive, a stolen laptop, a fire at the office or ransomware that encrypts everything it can reach.

Make it real

Automate the backups so they do not depend on memory, keep one copy disconnected from your network, and test restoring a file every few months.