Always On Availability Groups can support up to nine availability replicas, and while we don’t use anywhere near that many replicas in each of our clusters, we do have 2 replicas per cluster (3 servers total), with the replicas being used as a readable secondary.
Since we use readable secondaries in our environments, the application needs to connect to both the primary and the secondary servers with the same login. The catch is, logins don’t automatically sync across replicas. If the logins don’t sync, the application won’t connect to a secondary, which results in login failures.
Read on for one way to solve the problem.