Disaster Recovery
The process of restoring IT systems and data after a catastrophic event, including backup strategies, failover mechanisms, and recovery procedures.
Detailed Explanation
Disaster recovery (DR) is the plan and infrastructure for recovering from major failures: data center outages, natural disasters, cyber attacks, or hardware failures. DR strategies include: backup and restore (cheapest, slowest), pilot light (minimal standby infrastructure), warm standby (scaled-down replica), and multi-site active-active (full replica, most expensive).
Key DR metrics: RTO (Recovery Time Objective, how long to restore) and RPO (Recovery Point Objective, how much data loss is acceptable). A system with RTO of 1 hour and RPO of 5 minutes must restore within 1 hour and lose at most 5 minutes of data.
Why It Matters
Disaster recovery ensures business continuity when things go wrong. Without DR, a major failure can mean permanent data loss and extended downtime.
Real-World Example
A company replicates its database to a different region. If the primary region goes down, they promote the replica to primary and redirect traffic. RTO: 15 minutes. RPO: 0 (synchronous replication).
When to Use
For every production system with data. DR requirements depend on business impact: financial systems need RPO near zero; blogs can tolerate hours of data loss.
Advantages
- Ensures business continuity
- Minimizes data loss
- Enables recovery from major failures
- Supports compliance requirements
- Provides peace of mind
Disadvantages
- Requires investment in redundant infrastructure
- DR testing is complex and time-consuming
- Can increase operational complexity
- Overkill for non-critical systems
- RPO/RTO tradeoffs affect cost
Related Terms
Frequently Asked Questions
What is the difference between backup and disaster recovery?
Backup is copying data for protection. DR is the entire plan for restoring systems after a disaster. Backups are part of DR, but DR also includes failover, communication plans, and recovery procedures.
What are RTO and RPO?
RTO is how long you can be down (Recovery Time Objective). RPO is how much data you can lose (Recovery Point Objective). RTO=1hr means restore within 1 hour. RPO=5min means lose at most 5 minutes of data.
How often should I test disaster recovery?
At least quarterly. DR testing includes: verifying backups are restorable, testing failover mechanisms, practicing communication plans, and timing recovery procedures. Untested DR plans often fail when needed.
What is the 3-2-1 backup rule?
Keep 3 copies of data, on 2 different media types, with 1 offsite. This ensures protection against hardware failure, data corruption, and site-wide disasters. Modern additions: 3-2-1-1 (1 copy immutable/offline).
What is chaos engineering?
Chaos engineering is intentionally injecting failures into systems to test resilience. Tools like Chaos Monkey randomly terminate instances. The goal is to find weaknesses before they cause real outages.