Help Center/ Well-Architected Framework/ Well-Architected Framework and Practices/ Resilience Pillar/ Cloud Service Reliability/ ELB/ Reliability Functions
Updated on 2025-05-22 GMT+08:00
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Reliability Functions

Cluster HA

Load balancers of ELB can be deployed in clusters. They can route traffic across AZs, ensuring that your services are uninterrupted. If servers in an AZ are unhealthy, ELB automatically routes traffic to healthy servers in other AZs.

Backend Server Health Checks

ELB periodically sends requests to backend servers to check whether they can process requests. If a backend server is identified as unhealthy, the load balancer will route requests to healthy servers, which improves service reliability. After the backend server recovers, the load balancer will resume routing requests to it.

For details, see Health Check.

Cross-AZ DR

Load balancers of ELB can be deployed in clusters. They can route traffic across AZs, ensuring that your services are uninterrupted. If servers in an AZ are unhealthy, ELB automatically routes traffic to healthy servers in other AZs.

Backend servers of ELB can be deployed across AZs. If an ECS in an AZ is unhealthy, ELB can forward traffic to ECSs in other AZs, improving the fault tolerance of applications.

Monitoring

Using Cloud Eye, you can monitor ELB metrics such as the number of connections, bandwidth, and abnormal responses.

For details, see Monitoring Metrics.

Parent topic: ELB