Reference
Backup and recovery glossary: RPO, RTO, 3-2-1, immutable, and more
Plain-English definitions of the backup and recovery terms that matter: RPO and RTO, the 3-2-1 rule, immutable and air-gapped backups, WORM, runbooks, and restore testing.
- Recovery Point Objective (RPO)
- How much data loss a recovery plan is built to tolerate, measured in time. An RPO of one hour means you accept losing up to the last hour of changes.
- Recovery Time Objective (RTO)
- How long the business is prepared to wait for a service to come back. It covers the whole path: restore, access, dependencies, and the decision to go live.
- The 3-2-1 rule
- Keep at least three copies of important data, on two different kinds of media, with one copy kept off-site.
- Immutable backup
- A backup that cannot be changed or deleted for a set period, even by an administrator. The single strongest defense against ransomware that targets backups first.
- Air-gapped backup
- A copy kept physically or logically disconnected from the network, so an attacker who reaches your systems cannot reach it.
- Write Once Read Many (WORM)
- Storage that accepts data once and then only allows reading, not overwriting or deleting, until a retention period ends.
- Restore test
- A controlled exercise that actually recovers a selected system to a safe location and checks that the data comes back usable.
- Recovery Evidence Pack
- A portable, dated record of what is protected, what was tested, what came back, and what still needs work.
- Runbook
- A written, step-by-step recovery procedure: roles, dependencies, sequence, validation, and who decides the service is back.
- Multi-factor authentication (MFA)
- Requiring a second proof of identity beyond a password. On backup and administrator accounts it is one of the highest-value protections against account takeover.