Active components report their status to an MVS Event Manager every ten seconds. An active component is considered unavailable if it reports that it is unable to provide service for 60 seconds, or if it fails to report its status for 60 seconds. Only two MVS Event Manager instances are required to support the high availability pair because the MVS Event Manager instances use an active-active redundancy model. The status of all components in the BlackBerry Domain is shown on the MVS Console Dashboard.
In a high availability environment, the MVS Witness Server instances monitor the status of all MVS Session Manager instances and all MVS BlackBerry Enterprise Server Connector instances in the BlackBerry Domain. If an active MVS Session Manager or MVS BlackBerry Enterprise Server Connector component becomes unavailable, an MVS Witness Server facilitates the failover of service to the standby component.
During failover, active calls are not affected but BlackBerry Mobile Voice System users cannot use the features that are typically available to them during a call. The users also cannot send or receive a second call. In addition to this automatic process, you can manually start a failover through the MVS Console.
Only two MVS Witness Server instances are required to support the high availability pair because the MVS Witness Server instances use an active-active redundancy model. The MVS Witness Server instances themselves determine which one handles a particular failover.