The BlackBerry Mobile Voice System high availability installation is illustrated below.

High availability is achieved through active-active and active-standby models of redundancy. The following table summarizes the redundancy model for each BlackBerry MVS component:

In an active-standby model, high availability is achieved when one BlackBerry MVS Server is associated with another, to form the high availability pair. When you associate two MVS Session Manager instances, one of the MVS Session Manager instances becomes active and the other standby. The same holds for the two MVS BlackBerry Enterprise Server Connector instances: one becomes active, one standby. The components themselves determine which one becomes active and which one standby. If the active component fails, failover from the active component to the standby component is managed by the components in conjunction with the MVS Witness Server.

In an active-active model, components are always active. If a component fails, BlackBerry MVS automatically stops using that component. High availability is achieved by providing two components of the same type at the BlackBerry Domain level.

For example, because MVS Data Manager instances use an active-active model, two MVS Data Manager instances provide redundancy for all BlackBerry MVS Server instances in the BlackBerry Domain. By comparison, there must be one active and one standby MVS Session Manager for every high availability pair.