A simple backup strategy: the 3-2-1 rule
The 3-2-1 backup rule calls for three copies of important data, stored on two kinds of media or devices, with one copy kept offsite. It was popularized by photographer Peter Krogh in a 2009 book and is meant to protect files from drive failures, theft, fire, floods and other disasters. The approach emphasizes redundancy and has adapted as storage technology has changed.
Photographer Peter Krogh brought the 3-2-1 approach to wider attention in a 2009 book about managing digital assets. The framework asks for three copies, two storage types or devices, and one copy kept elsewhere. Its purpose is resilience against hardware failure, theft, fire, flooding, and similar losses.
As storage has shifted, interpretations have loosened. Optical discs matter less, while cloud services and external drives are common. A networked offsite copy can still be hit by ransomware, and some cloud sync setups may remove files everywhere when one is deleted. Individual needs differ from large organizations.
The 3-2-1 rule may influence how individuals and small organizations think about data safety, especially as personal photos, records, and work files become more central to daily life. Wider adoption could reduce losses from device failure, theft, fire, or ransomware, though cost, technical skill, and cloud-sync pitfalls may limit its reach. Its impact may depend on whether users can maintain multiple copies and an offsite location.