When you change the Universal Messaging source service of a service group, make sure that the Universal Messaging server specified in the original source service is running when Digital Event Services (DES) is applying the configuration change. DES applies the new configuration shortly after you make the changes in Command Central when the runtime in which DES is embedded is started, or the next time when the runtime is started.

If the Universal Messaging server for the original source service is unavailable when DES is processing the configuration change, the durable subscription objects on the channel of the source Universal Messaging server are not deleted. As a result, any events sent to this Universal Messaging channel are kept on it and consume memory. Even if you configure the new source service to use the original Universal Messaging server again, the events sent prior to this change do not reach the subscribers for the event type.