With Unity you can have a pair of servers configured as a failover pair. They work as active/passive and are essentially a single server as far as licensing goes. It isn’t an active/active model like CallManager has. A failover pair shares the same, single license file via SQL replication and subscribers aren’t homed to one or the other. The servers don’t each over the own license.
License Pooling on the other hand is used to share licenses between servers in the directory. The data is written to the location object and replicated by monitoring the directory. A failover pair can share licenses between other servers or pair of servers if License Pooling is enabled but again not between eachother.
Hope that explains it...
Keith
