3-2-1 backup rule

The 3-2-1 backup rule is a data protection strategy designed to eliminate single points of failure. It provides a framework for redundancy ensuring data recoverability in case of hardware failure, site-wide disasters, or cyberattacks. This approach is the industry standard for professional data management.

Core Components

• 3 copies of data: Keep the primary data and two additional backups. This ensures that if one backup is corrupted, another remains available.
• 2 different media types: Store backups on distinct storage technologies, such as RAID arrays and Object Storage. This mitigates risks associated with specific hardware vulnerabilities.
• 1 copy off-site: Maintain at least one backup in a separate physical location. This protects against localized disasters like fires or physical theft of infrastructure.

If the probability of failure for one drive is 1/100, the chance of two independent drives failing simultaneously is 1/10,000. Adding a third off-site copy reduces the statistical risk of total data loss to near zero. Modern infrastructures often extend this to 3-2-1-1-0, adding immutable copies to defend against ransomware encryption.