ELB Metrics and Dimensions

This section discusses the Elastic Load Balancing (ELB) metrics and dimensions available to CloudWatch.

Available Metrics for ELB

Metric Description Unit
Latency Time elapsed after the request leaves the load balancer until it receives the corresponding response. Valid Statistics: Minimum Maximum
RequestCount The number of requests handled by the load balancer. Count
HealthyHostCount The number of healthy instances registered with the load balancer in a specified availability zone. Healthy instances are those that have not failed more health checks than the value of the unhealthy threshold. Constraints: You must provide both LoadBalancerName and AvailabilityZone dimensions for this metric.Valid Statistics: Minimum Maximum
UnHealthyHostCount The number of unhealthy instances registered with the load balancer. These are instances that have failed more health checks than the value of the unhealthy threshold. Constraints: You must provide both LoadBalancerName and AvailabilityZone dimensions for this metric.Valid Statistics: Minimum Maximum
HTTPCode_ELB_4XX Count of HTTP response codes generated by ELB that are in the 4xx (client error) series. Valid Statistics: Sum Count
HTTPCode_ELB_5XX Count of HTTP response codes generated by ELB that are in the 5xx (server error) series. ELB can generate 5xx errors if no back-end instances are registered, no healthy back-end instances, or the request rate exceeds ELB’s current available capacity. This response count does not include any responses that were generated by back-end instances. Valid Statistics: Sum Count
HTTPCode_Backend_2XX Count of HTTP response codes generated by back-end instances that are in the 2xx (success) series. Valid Statistics: Sum Count
HTTPCode_Backend_3XX Count of HTTP response codes generated by back-end instances that are in the 3xx (user action required) series. Valid Statistics: Sum Count
HTTPCode_Backend_4XX Count of HTTP response codes generated by back-end instances that are in the 4xx (client error) series. This response count does not include any responses that were generated by ELB. Valid Statistics: Sum Count
HTTPCode_Backend_5XX Count of HTTP response codes generated by back-end instances that are in the 5xx (server error) series. This response count does not include any responses that were generated by ELB. Valid Statistics: Sum Count

Available Dimensions for ELB

You can use the currently available dimensions for ELB to refine the metrics returned by a query. For example, you could use HealthyHostCount and dimensions LoadBalancerName and AvailabilityZone to get the average number of healthy instances behind the specified load balancer within the specified Availability Zone for a given period of time.

You can aggregate ELB data along any of the following dimensions shown in the following table.

Metric Description
LoadBalancerName Limits the metric data to instances that are connected to the specified load balancer.
AvailabilityZone Limits the metric data to load balancers in the specified availability zone.