High Availability (HA)
What is High Availability (HA)?
High availability is a design approach that keeps systems and services running with minimal downtime by reducing single points of failure. It uses redundancy, failover, and monitoring so services continue operating even when components fail.
Examples
- A web application runs behind a load balancer with two web servers, so if one server fails the service stays online.
- A firewall pair is configured in high availability mode so network connectivity continues if one firewall goes down.
Discover 🔎
Availability is a core security objective because users cannot safely use a system that is frequently down. High availability is the practical way organizations design for resilience. It is not only about hardware failure. It also helps during maintenance, misconfiguration, and even certain attacks. The goal is to make failures smaller and recovery faster so the business stays operational.
Summary 📝
High availability keeps services running by reducing single points of failure and using redundancy, health checks, and failover. It is easier for stateless services and more complex for stateful systems like databases. Strong HA designs focus on independence of components, regular failover testing, and operational readiness so that failures and maintenance cause minimal disruption.
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