Glossary term
What is 3-2-1 rule? Meaning for developers
3 copies, 2 media types, 1 off-site. Example: Database + backup in same cloud + backup in another region.
Learn it properly · System DesignLesson 45: Backups & Disaster Recovery: RPO vs RTOReplication faithfully copies a mistaken DELETE, ransomware or silent corruption to every replica in milliseconds. Why backups are a different thing, how RPO and RTO drive every decision, point-in-time recovery, the 3-2-1 rule, the four DR strategies, and why an untested backup is only a hope.