3-2-1 backups and immutability
Design backups that survive hardware failure, disasters and ransomware: 3-2-1, immutable copies, RPO/RTO math and honest restore testing.
- Level
- Intermediate
- Length
- About 50 minutes
- Contents
- 3 lessons · 1 video · final exam
- Status
- Published · updated 1 Oct 2026
Skills you'll practise
- Check a backup design against the 3-2-1 rule
- Explain what immutable and offline copies protect against
- Calculate data loss from a backup interval (RPO) and restore time from data size and throughput (RTO)
- Plan and record a restore test
Course outline
- 1.3-2-1 backups, immutability and restore mathVideo · 2 min
- 2.3-2-1 and immutabilityLesson · 20 min
- 3.RPO, RTO and restore testingLesson · 20 min
- 4.Protecting the backup system itselfLesson · 20 min
- 5.3-2-1 backups and immutability: knowledge checkKnowledge check · 25 questions
- 6.3-2-1 backups and immutability: practical exerciseKnowledge check · 1 question
- 7.“We have snapshots, so we're backed up”Scenario
- 8.Final exam8 questions · passing it completes the course, so people who already know the material can test out
Sources it draws on
The lessons and questions are written from these references, so learners can go back to the original.
- NIST SP 800-34 Rev. 1: Contingency Planning Guide
- CISA #StopRansomware Guide (offline, encrypted backups; testing)
- Object storage write-once-read-many (WORM) / object lock concepts (governance vs compliance modes)
See it with your own jobs and topics
Tell us about your team and we'll walk you through setup, from choosing jobs to your first skills check.