Backups are not optional:
Backup strategies:
- Full: Complete copy. Large, slow.
- Incremental: Only changes since last backup. Fast but complex restore.
- Snapshot: Point-in-time image. Fast if storage supports it.
-- rule: copies, different media types, offsite. Protects against various failure modes.
Testing: Regularly restore from backup. Untested backups aren't backups.
RTO and RPO: Recovery Time Objective (how fast you recover). Recovery Point Objective (how much data you can lose). Design backups to meet both.