Description

This check verifies if an Amazon EC2 Auto Scaling group extends across a minimum of two Availability Zones (AZs). Allowed values range from 2 to 6 AZs.

An Auto Scaling group limited to one AZ is not able to initiate instances in a different AZ should the active AZ go down. However, there are scenarios, such as batch processing or situations where minimizing inter-AZ data transfer costs is crucial, and having an Auto Scaling group in a single AZ might be beneficial. In these instances, the check can be turned off or its alerts can be ignored.

Remediation

For instructions on adding AZs to an existing Auto Scaling group, refer to the section on adding and removing Availability Zones in the Amazon EC2 Auto Scaling User Guide.