Nov 20, 2024 · 5 min read
High availability is not just about preventing failures—it is about designing systems that continue operating when failures inevitably occur. The goal is to minimize downtime and ensure that users experience consistent service regardless of underlying infrastructure issues.
Redundancy is the foundation of high availability. This means eliminating single points of failure by having multiple instances of critical components. Whether it is multiple web servers behind a load balancer, replicated databases, or redundant network paths, duplication ensures that no single failure brings down the system.
Load balancing distributes traffic across healthy instances and automatically removes unhealthy ones from rotation. Understanding health check configurations and failover behavior is crucial. I have learned that aggressive health checks can cause cascading failures, while too lenient ones delay failover.
Geographic distribution adds another layer of resilience. Deploying across multiple availability zones or regions protects against datacenter-level failures. However, this introduces complexity in data synchronization and increases latency for cross-region communication.
Monitoring and alerting are essential companions to high availability design. Knowing when failures occur—and ideally predicting them—allows for proactive intervention. I focus on meaningful metrics like error rates and latency rather than just CPU and memory utilization.
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