Skip to content

3-2-1 Rule for Data Backup

Introduction

The 3-2-1 rule for data backup is a trusted strategy for ensuring your data remains secure and recoverable in case of loss or failure. It’s based on three simple principles:

  • 3 Total Copies: Maintain at least three copies of your data—one primary (working) version and two backups.

  • 2 Different Storage Types: Use at least two different types of storage media to minimize the risk of simultaneous failure. For example, combine an external hard drive with a cloud service or use both SSDs and institutional servers.

  • 1 Off-Site Copy: Keep at least one copy in a separate physical location, such as a cloud backup or a secure off-site facility. This adds a vital layer of protection against disasters like fire, theft, or system-wide failure.

Following the 3-2-1 rule significantly improves your chances of data recovery and strengthens overall data resilience.

Example

A simple example of the 3-2-1 rule in practice.

Keep the original data on your computer, back it up to an external hard drive, and store a third copy in the cloud.

Breakdown

3 Copies

  • Original on your computer
  • Backup on an external hard drive
  • Additional copy in the cloud

2 Different Storage Types

  • Physical storage: computer’s internal drive and external hard drive
  • Online/cloud storage: cloud backup service

1 Off-Site Copy

  • The cloud copy is stored in a separate physical location, protecting against local disasters like fire, theft, or hardware failure

Note

The TCA Data Management Accelerator is available to assist with creating and implementing backup strategies. They also provide free cloud storage services locations for your research data backups.

Warning

Check with your institution or funding agency to see if they have a policy on data storage and backup. You may be required to use a specific service for sensitive data.