Redundant Backup (3-2-1 Rule)

A Simple Strategy for Data Survival

The 3-2-1 rule is a simple, memorable, and powerful strategy for ensuring data redundancy and disaster recovery. On a modern film set, where the footage captured is the single most valuable asset, losing the original camera files is a production-ending catastrophe. The 3-2-1 rule is the industry-standard methodology employed by every professional Digital Imaging Technician (DIT) and data manager to prevent this from ever happening.

Breaking Down the Rule

The strategy is a straightforward recipe for creating robust backups:

• THREE Total Copies of Your Data

  1. The original data on the primary media (e.g., the camera’s memory card).
  2. A first backup copy (often on a high-speed RAID storage array on the DIT cart).
  3. A second backup copy (on a separate drive or set of drives).

• On TWO Different Types of Media

  • This protects against a specific technology failing. For example, the primary media might be solid-state (CFexpress or SD cards), while the backups are on spinning hard disk drives or, for long-term security, on LTO magnetic tape.

• With ONE Copy Stored Off-Site

  • This is the most critical step for disaster recovery. It protects against a localized event like a fire, flood, or theft at the primary location. At the end of each shooting day, a set of backup drives (known as ‘shuttle drives’) is physically transported to a secure, separate location, such as the production office, a local post-house, or a hotel safe.

By adhering to this rule, a production ensures that no single point of failure—a dropped drive, a corrupt card, a stolen bag—can lead to the permanent loss of their irreplaceable footage.