Failover is a backup operation that automatically switches to a redundant or standby system, server, or component in the event of a failure or outage. It ensures that services, applications, or systems remain operational even during hardware or software failures, minimizing downtime and maintaining system availability.
Key components of failover include:
- Redundancy: Failover relies on having a backup system or component that can take over when the primary system fails. This may involve redundant servers, storage systems, or network paths.
- Automatic Switching: In a failover system, the transition from the failed component to the backup occurs automatically without requiring manual intervention. This ensures quick recovery and minimal service disruption.
- High Availability: Failover is a key component of high availability (HA) architectures, ensuring that critical services are always accessible, even during system failures.
- Load Balancing: In some systems, failover is integrated with load balancing, where traffic is distributed between multiple servers or instances. If one server fails, the load balancer redirects traffic to another functioning server.
- Types of Failover:
- Active-Passive: One system is active, while the other remains passive (on standby). If the active system fails, the passive system becomes active.
- Active-Active: Multiple systems are active simultaneously, and if one fails, the remaining active systems continue to handle the load.
- Failover Testing: Periodic testing of the failover system ensures that the backup systems are functioning properly and can take over seamlessly when needed.
Failover systems are critical for maintaining the reliability, stability, and availability of services, especially for mission-critical applications that require minimal downtime and constant availability.