Unity to Exchange Connections

Increasing the Number of Connections

If you have more than 2000 users on a Unity Connection server or more than 80 milliseconds of latency, you can increase the number of connections from the default value of four. Note the following:

• The maximum number of connections is 64.
• Never decrease the number of connections to fewer than four.
• After you change the number of connections, you must restart the Unity Connection Mailbox Sync service in Cisco Unity Connection Serviceability for the change to take effect.
• As Unity Connection is optimized in future versions, the optimum number of the connections for a specific environment may change.
• If you have more than one Unity Connection server synchronizing with the same Exchange server or CAS array, you may increase the processor load on the Exchange CAS servers to unacceptable levels.

To increase the number of connections that Unity Connection uses for synchronizing with each Exchange server, run the following CLI command (when a Unity Connection cluster is configured, you can run the command on either server):

run cuc dbquery unitydirdb EXECUTE PROCEDURE csp_ConfigurationModifyLong (pFullName=’System.Messaging.MbxSynch.MbxSynchThreadCountPerUMServer’, pValue=<value>)

where < value > is the number of connections that you want Unity Connection to use.

To determine the current number of connections that Unity Connection is configured to use, run the following CLI command:

run cuc dbquery unitydirdb select fullname, value from vw_configuration where fullname = ‘System.Messaging.MbxSynch.MbxSynchThreadCountPerUMServer’

Calculating the Number of Connections for a Unity Connection Server That Is Synchronizing with an Exchange CAS Array

Unity Connection is most likely to require a large number of connections with Exchange or Office 365 when connecting with a large CAS array. For example, when the Unity Connection server has 12,000 single-inbox users and the latency is 10 milliseconds, you would increase the number of connections to six:

Number of connections = (12,000 * (10 + 15)) / 50,000 = 300,000 / 50,000 = 6 connections

If your Exchange environment includes both a large CAS array and one or more Exchange or Office 365 servers that are not in the array, and if the calculated number of connections for the CAS array differs significantly from the number of connections for the individual Exchange or Office 365 servers, you may want to consider adding a Unity Connection server that is dedicated to the separate Exchange or Office 365 servers. Setting the number of connections to the lower value—for the standalone Exchange or Office 365 servers—will mean synchronization delays for the CAS array, while setting the number of connections to the higher value—for the CAS array—will mean a higher processor load on the standalone Exchange or Office 365 servers.