🛡️ Failover Strategies — Building Resilient Systems

Failover ensures your system stays available even when parts of it fail. It's a core part of designing for high availability and disaster recovery.

🔄 Active-Passive

• How: One server is active, another is on standby.
• Use When: Simplicity is more important than instant recovery.
• Example: A primary database with a standby replica that takes over if the primary fails.
• Considerations: There may be a short downtime during failover. Regular health checks and automated failover scripts are essential.

🔁 Active-Active

• How: Multiple servers handle traffic simultaneously.
• Use When: Need instant failover and load balancing.
• Example: Two or more web servers behind a load balancer, all serving requests.
• Considerations: Data consistency and conflict resolution can be challenging. Useful for stateless services.

🌎 Geo-Redundancy

• How: Deploy across multiple regions or data centers.
• Use When: Protecting against regional outages.
• Example: Cloud providers like AWS offer multi-region deployments for critical applications.
• Considerations: Data replication latency and regulatory compliance (data residency) may be factors.

🧪 Testing Failover

• Chaos Engineering: Tools like Chaos Monkey can simulate failures to test your failover mechanisms.
• Disaster Recovery Drills: Regularly practice failover to ensure your team and systems are ready.

🧠 Final Thoughts

Test your failover! Practice disaster recovery to ensure your strategies work when you need them most. Remember, a failover plan is only as good as its last test.