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. Because MVS Event Manager instances use an active-active redundancy model, only two are required to support all BlackBerry® MVS Server instances in the BlackBerry Domain. The status of all components in the BlackBerry Domain is shown on the MVS Console Dashboard.
In a high availability environment, MVS Witness Server instances monitors 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 might find that mid-call features do not work. New calls cannot be started or accepted. In addition to this automatic process, you can manually start a failover through the MVS Console.
Because MVS Witness Server instances use an active-active redundancy model, only two are required to support all high availability pairs in the BlackBerry Domain. The MVS Witness Server instances themselves determine which one handles a particular failover.