3-2-1 backup rule
Apply the 3-2-1 backup rule: maintain at least 3 copies of critical data, on at least 2 different media types, with at least 1 copy stored offsite.
When This Fires
- When setting up backup infrastructure for your critical data
- When reviewing existing backup strategies for adequacy
- When any single point of failure exists in your data protection
- Complements Choose open portable formats (Markdown, CSV, JSON) over… (open portable formats) with the backup infrastructure that protects the data regardless of format
Common Failure Mode
Single-backup complacency: "I back up to an external drive, so I'm protected." A single backup on the same desk as your computer is defeated by theft, fire, flood, or power surge. You have 2 copies on 1 media type with 0 offsite — failing on two of the three criteria.
The Protocol
(1) Identify your critical data: notes, writing, projects, financial records, photos, code. (2) Implement 3 copies: Copy 1 — primary working copy (laptop/desktop). Copy 2 — local backup (external drive, NAS, or separate internal drive). Copy 3 — offsite backup (cloud service, remote server, or physical drive stored elsewhere). (3) Verify 2 different media types: if copies 1 and 2 are both on SSDs, make copy 3 on a different medium (cloud storage, magnetic drive). (4) Verify 1 offsite: at least one copy must be in a different physical location. Cloud backup satisfies this automatically. (5) Automate: backups that require manual action will eventually be skipped. Set up automated backup for copies 2 and 3 so protection doesn't depend on remembering.