3-2-1-1-0 Backup Rule is an extension of the 3-2-1 rule recommending three copies, two media types, one offsite copy, one offline/immutable copy, and zero verified errors.
Simple definition
3-2-1-1-0 Backup Rule is an extension of the 3-2-1 rule recommending three copies, two media types, one offsite copy, one offline/immutable copy, and zero verified errors. It belongs to the Backup / PRA vocabulary and is useful when reading architecture diagrams, product documentation, logs, or administration procedures.
What is it used for?
Its main purpose is to design a backup strategy resilient to local failures, ransomware, and silent corruption. The practical value depends on the surrounding architecture, security model, and operational requirements.
How does it work?
The rule combines copy/media/location diversity with verification so the last copy is not only present but restorable.
Key points
- Scope: An extension of the 3-2-1 rule recommending three copies, two media types, one offsite copy, one offline/immutable copy, and zero verified errors.
- Operational goal: Design a backup strategy resilient to local failures, ransomware, and silent corruption.
- Implementation: The rule combines copy/media/location diversity with verification so the last copy is not only present but restorable.
Points to watch
A backup is reliable only if restore is tested; document RPO/RTO, retention, immutability, and chain dependencies.
In short
3-2-1-1-0 Backup Rule = an extension of the 3-2-1 rule recommending three copies, two media types, one offsite copy, one offline/immutable copy, and zero verified errors. Use it when you need to design a backup strategy resilient to local failures, ransomware, and silent corruption.