HA Configuration

In a high availability configuration, multiple ADSS Server instances may be deployed to ensure continuous operation of the Inspection System Service. Certain background tasks, such as polling trust data (e.g., Master Lists and CRLs) from the DVCA/PKD services, must be performed by only one instance at a time. This instance is referred to as the Primary. Allowing multiple instances to perform the same polling task simultaneously would result in duplicate processing and unnecessary system load.

However, this introduces a potential risk where the Primary instance becomes a single point of failure. If the Primary instance becomes unavailable, polling and related background operations would stop. To address this, the Inspection System Service supports a high availability mechanism. In this setup, one or more Secondary instances continuously monitor the status of the Primary. If the Primary becomes inactive, a Secondary instance can automatically take over and become the new Primary, ensuring uninterrupted service.

All ADSS Server instances share the same database and use it to determine their current role (Primary or Secondary). The first installed instance typically acts as the Primary, while others function as Secondary instances. For each additional Secondary instance, the number of checks to confirm Primary inactivity is increased to avoid conflicts during failover.

Navigate to Inspection System Service 🡪 HA Configuration, it displays the following screen:

The configuration items are as follows:

Items	Description
Secondary should check Primary active status every (sec)	Defines the time interval (in seconds) at which a Secondary instance checks whether the Primary instance is active.
Number of times secondary should re-check before Primary	Specifies how many times a Secondary instance should re-check the Primary’s status before assuming it is inactive. For additional Secondary instances, this value is automatically increased to avoid simultaneous takeover attempts.
Inspection System Service Host	Specifies the host address of the Inspection System Service instance used for communication and identification in a high availability setup.