2.4 does not have clustering support. Unity 2.4.5 will have simple two box fail over capabilities, but not true “clustering”. We are working on a true clustering model for a future version of Unity.
When I use the term clustering I assume that means several boxes working together such that when one goes down another one in the cluster picks up it’s duties and carries on seamlessly, as transparent to outside callers and subscribers as possible. This implies interbox communication (i.e. heartbeats) and the like. We are working on this type of functionality but it is not in 2.4 and will not be in the 2.4.5 later this year.
The simple fail over capability planned for 2.4.5 is very basic, intended to handle a catastrophic failure of the primary Unity server. Two boxes can be configured in a “primary” and “secondary” configuration such that when the primary goes down, calls are answered by the secondary box. For this to work the mail users in the organization must be homed on Exchange servers off the Unity boxes, of course… if the box your Exchange server that has your message store on it lights up and hits the dirt, those messages will not be available to us, of course.
The basic idea is lines from the switch will be “Y” connected to both the primary and the secondary box. The secondary needs to be set to answer on, say, 3 rings and the primary on the first ring. When the primary goes down, the secondary will pick up the calls. If the switch we're connected to can handle it, you can get fancier by having multiple hunt groups configured to fail over to each other and the like, but the principal is the same: when the ports on the primary Unity box don't answer, the call gets picked up by lines on the secondary Unity box.
Subscriber information, greetings, voice names, call handlers, interviewers etc… are all replicated between the two boxes so it’ll only be necessary for administrators to make changes on the primary box. The only exception to that is routing rules and the switch configuration settings. Assuming those stay pretty static, once you have your two servers configured, it should be fairly transparent.
Jeff Lindborg
Unity Product Architect
Active Voice Corp
jlindborg@activevoice.com
