The External Controller High Availability (HA) provides a failover mechanism where one of the Controllers is always active and reachable. External Controller HA is achieved using auto scaling in the Azure environment. You have to create an auto scaling group for Controller so that when the Controller is not reachable, a new Controller with the same properties as the previous Controller is created.
Note
High Availability is not available for Local Controllers.
In case of External Controller HA with MDR Managers, the Controller first tries to register with the Primary Manager. If the Primary Manager is in standby mode or is not reachable, the Controller registers with the Secondary Manager. Once the Primary Manager is active again, you should retrieve the Controller configuration from the Secondary Manager manually.
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Trellix recommends you to deploy the Controller in an auto scaling group with the size specified as 1. At any time, only one Controller can exist in an high availability pair, as the Controllers will have the same properties like name, etc. When the Controller is not reachable, the auto scaling group creates another Controller with the same properties as the old Controller.