3-2-1 Backup Rule Coverage Checker
Verify whether your current backup strategy satisfies the industry-standard 3-2-1 rule: 3 total copies of data, on 2 different storage media types, with 1 copy stored offsite.
Fill in your backup details above to check compliance.
Formula & Logic
3-2-1 Rule Compliance:
• Rule 3: total_copies ≥ 3
• Rule 2: media_types ≥ 2
• Rule 1: offsite_copies ≥ 1
Coverage Score (%):
Coverage = (rules_passed / 3) × 100
Monthly Storage Cost:
Cost = total_copies × data_size_GB × cost_per_GB
Cost Gap (to reach minimum 3-2-1):
Gap = max(0, (3 × data_size_GB × cost_per_GB) − current_cost)
Assumptions & References
- The 3-2-1 rule was popularized by photographer Peter Krogh and is widely adopted in IT and data management.
- "Offsite" includes cloud storage (AWS S3, Google Cloud, Azure Blob), remote physical locations, or off-premises tape.
- Media types include: internal HDD/SSD, external HDD, NAS, tape, optical disc, cloud object storage, etc.
- The original data counts as one of the three copies.
- Default cost of $0.023/GB/month reflects AWS S3 Standard pricing (us-east-1, 2024); actual costs vary by provider and tier.
- Coverage score weights all three rules equally (33.33% each).
- This checker evaluates quantity and diversity of backups only; it does not assess backup integrity, encryption, or recovery time objectives (RTO/RPO).
- Reference: NIST SP 800-34 Rev. 1 — Contingency Planning Guide for Federal Information Systems.