3-2-1 Backup: Copies, Locations, and Offsite Storage Explained Simply
The 3-2-1 backup approach is often described as a rule, but it's really a framework — a minimum viable structure for data protection that has proven reliable across decades of changing technology. Understanding what each component means in practice helps you implement it correctly rather than just checking a box. Three Copies: What Counts The three in 3-2-1 refers to total copies of your data, including the original. Your production data is copy one. Your first backup is copy two. Your second backup — typically stored in a different location or on a different media type — is copy three. The key is that these are genuinely independent copies. A RAID array is not a backup — it protects against drive failure but not against accidental deletion, ransomware, or controller failure. Two Media Types: Why It Matters The two-media requirement exists to protect against media-specific failures. If both your backup copies live on the same type of hardware, they may share vulnerabilities. ...