In this model, UTM is deployed on a primary EC2 instance in a single Availability Zone (AZ) with a secondary EC2 instance in a different AZ. Using CloudFormation, Amazon Simple Storage Service (S3), and Health Checks for Auto Scaling instances, UTM leverages services to determine the status of the primary EC2 instance. If the primary EC2 instance fails a health check, the Auto Scaling group transfers the Elastic IP Address and all configuration settings stored in S3 over to the secondary EC2 instance in a different AZ. You can select between cold standby (secondary EC2 instance has not been started) and warm standby (secondary EC2 instance is running in parallel with the primary EC2 instance but not actively inspecting traffic).
Stand Alone with HA