This feature is a high-availability and disaster recovery solution provided by Microsoft SQL Server. In this type of configuration, there are three entities: Principal SQL Server, Mirror SQL Server, and Witness SQL Server, wherein Principal SQL Server serves as the primary/production instance, and Mirror SQL Server serves as a backup or high-availability instance. Both Principal and Mirror SQL Servers are in real-time synchronization, and changes are replicated on the Mirror SQL Server as per the changes made on the Principal SQL Server.
With the Utimaco HSM integration, data encrypted on the Principal SQL Server database can be decrypted from the Mirror SQL Server by using the same configuration and environment when the Failover Scenario occurs.