The following diagram shows how you can configure the BlackBerry® Configuration Database with principal and mirror instances for high availability. The BlackBerry Configuration Database supports an optional witness. The BlackBerry® Enterprise Server connects to the principal BlackBerry Configuration Database directly, and can fail over to the mirror BlackBerry Configuration Database if the principal BlackBerry Configuration Database stops responding.

The primary BlackBerry Enterprise Server connects to the principal BlackBerry Configuration Database and accesses data from it. The name of the mirror BlackBerry Configuration Database is stored in the Windows® registry of the computers that hosts the primary and standby BlackBerry Enterprise Server instances. The BlackBerry Enterprise Server instances do not connect to the mirror BlackBerry Configuration Database until after the principal BlackBerry Configuration Database stops responding.

The primary BlackBerry Enterprise Server connects to the messaging server and processes the messaging data that it sends to and receives from BlackBerry devices.

The standby BlackBerry Enterprise Server opens standby connections to the principal BlackBerry Configuration Database and the messaging server.