High-Availability and Redundancy
As of version 7.x software, Cisco Unity Connection supports the active-active cluster pair configuration. This configuration is defined as active-active because both servers actively process calls. In the active-active cluster pair configuration, the active-active cluster pair can support up to 500 ports (250 ports/server) simultaneously, depending on the server platform. If one server in a cluster pair is unavailable, the other server can handle all voice messaging, but with a decreased number of ports (maximum of 250 ports). Therefore, if high availability is a requirement, the total number of ports considered in the design should be kept at a maximum of 250 ports to ensure port availability during an outage. In this way, a server failure can still maintain the required number of ports.
The active-active cluster pair requires two servers with the same software level. The two servers are actively processing calls, even though a single database is still actively performing load sharing and providing redundancy in case of server failure. You can explore the active-active cluster pair design and configuration in the next chapter. At this time, you need to consider this model in your design if high availability is a requirement in tour voice-messaging solution.
Figure 2-2 illustrates the single server and active-active cluster pair design.
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Figure 2-2 Single Server and Active-Active Cluster-Pair Design