Disaster-Recovery

Introduction Disaster Recovery (DR) is the process, policies, and procedures for recovering and continuing technology infrastructure after a disaster. A disaster can be natural (earthquake, flood), technical (data center failure, ransomware), or human-caused (accidental deletion, security breach). Core Principle: “Hope is not a strategy. Plan for failure before it happens.” Key Concepts RTO vs RPO Time ─────────────────────────────────────────────────────────────> │ │ │ │ Disaster Detection Recovery Normal Occurs Time Begins Operations │◄──────────────────────────────────►│ │ Recovery Time │ │ Objective (RTO) │ │ │ │◄───────────►│ │ Data Loss │ (Recovery Point │ Objective - RPO) │ Recovery Time Objective (RTO) Definition: Maximum acceptable time that a system can be down after a disaster. …

Executive Summary Storage strategy = reliable data access with recovery guarantees. Choose based on workload (traditional vs. modern, single vs. multi-server). Why storage matters: Most production disasters involve storage—disk fills up and crashes your application, a database corruption loses customer data, or backups fail during a restore attempt. Proper storage management prevents these scenarios. Real-world disasters prevented by good storage: Disk full at 3 AM: Application logs fill /var → server crashes → customers can’t access site. Solution: Separate /var/log partition with monitoring. Failed database restore: Backup runs nightly for 2 years, never tested. Server dies, restore fails (corrupt backup). Solution: Monthly test restores. Database grows unexpectedly: 50GB database grows to 500GB in 3 months. Traditional partitions = downtime to resize. Solution: LVM allows online growth. Ransomware encrypts production data: No snapshots available, last backup is 24 hours old. Solution: ZFS/Btrfs snapshots provide instant point-in-time recovery. This guide covers: …