High Availability
High Availability (HA) is a design principle and architectural approach focused on ensuring systems remain operational and accessible with minimal downtime, typically targeting 99.9% uptime or higher. It involves implementing redundancy, failover mechanisms, and fault tolerance across hardware, software, and network components to prevent single points of failure. This concept is critical for mission-critical applications where continuous service is essential, such as in e-commerce, banking, or healthcare systems.
Developers should learn and apply High Availability designs when building or maintaining systems that require reliability and resilience, such as online services, databases, or cloud infrastructure, to minimize service disruptions and data loss. It is particularly important in distributed systems, microservices architectures, and environments with strict Service Level Agreements (SLAs), where downtime can lead to significant financial or reputational damage. Implementing HA helps ensure business continuity and user satisfaction by automatically handling failures without manual intervention.