Unity - Advanced Settings for 72+ Ports

By default Unity uses 1 MAPI connection to Exchange for a Unity system with 72 ports, If Unity has more than 72 ports and users complain of slowness in VM access (login to VM) or VM delivery to Exchange mailbox and the following event log is consistently observed in the App Event Log then you may look at changing the following settings:




On the Unity box goto to Tools Depot, expand the Administration Tools and double-click Advanced Settings Tool.In the left pane, click Messaging - 72 or More Voice Ports - Enable Low-Fragmentation Heap, In the New Value drop-down box, click 1 and click Set and when prompted click Ok,



Inthe Cisco Unity Advanced Settings window, in the left pane, click Messaging - 72 or More Voice Ports - Number of MAPI Sessions Per Exchange Server.

Number of VM Ports Setting
72 to 83 Click 2
84 to 95 Click 3
96 to 119 Click 4
120 to 143 Click 5
144 Click 6




When prompted that the value has been set, click Ok,Close Tools Depot and bounce Unity.

Note: If Exchange is experiencing high Disk I/O due to very high mailbox usage,under performing disk subsystem,migration/database replication applications reading writing to mailboxes/databases, then the above change will not make much difference as Exchange performance would be the root cause for slow VM access,The following Exchange perfmon counters will provide a good insight on Exchange performace,

Average Disk sec/Read - Average < 20ms, spikes < 50ms
Average Disk sec/Write - Average < 20ms, spikes < 50ms
RPC Averaged Latency - Always < 50ms

There are many counters to check Exchange Disk I/O but the above is suffice to judge Exchange performance.The below MS technet article gives a good insight on what causes Exchange Disk I/O:

http://technet.microsoft.com/en-us/library/aa996376(EXCHG.65).aspx