SQL Server Always On uses the Policy-Based Management(PBM) for determining its health. In the earlier articles, we discovered AG dashboard features to monitor synchronization status, data loss, replica states. It executes the PBM policies on availability replicas (primary and secondary), availability group database and organizes the results in a dashboard.
The primary replica contains information for all replicas, their synchronization states. It has sufficient information to compute the health for all availability groups. If we launch the AG dashboard from the primary and secondary replica, we can note the difference in monitoring.
This is perhaps the most under-developed and under-utilized feature in SQL Server. It is conceptually so powerful and what’s in there shows some of that power, but to this day, so much is still lacking in PBM.