3-2-1-1-0 Rule

The 3-2-1-1-0 rule

The 3-2-1-1-0 rule is an extension of the 3-2-1 rule  focusing on strengthening the cyber resilience of backup infrastructures. The numbers represent:

3 copies of all data (one copy can be the original)

2 locations/media (e.g., data centers or servers)

1 immutable copy (at least) – achieved through immutable storage, WORM devices, or immutable snapshots

1 offsite/offline copy: achieved by using offline media (e.g., tape) or copying the data via secure transport channels to a remote location or cloud. After copying, the data is neither visible, modifiable, nor deletable from the source system. Typically, there is no permanent connection between these systems, and authentication is required for each access.

0 errors through monitoring, updates, vulnerability remediation, and regular restore tests