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Monitoring for Server Memory Capacity Limits

 

Topic Last Modified: 2011-11-28

Two mobility performance counters can help you determine your current usage and help you plan capacity for the Microsoft Lync Server 2010 Mobility Service. The two primary Front End Server counters, under the category LS MCX – 00 – Mobile Communication Service, are:

  • Currently Active Session Count with Active Presence Subscriptions, which is the current number of endpoints registered through the Mobility Service that have active presence subscriptions (number of always-connected mobile users)

  • Currently Active Session Count, which is the current number of endpoints registered through the Mobility Service

If the difference between Currently Active Session Count with Active Presence Subscriptions and Currently Active Session Count is small over time, it means that most mobile device users have an always-connected device, such as an Android or Nokia mobile device. If Currently Active Session Count is much higher than Currently Active Session Count with Active Presence Subscriptions, it shows that more users are using a background endpoint device, such as an Apple iOS device or Windows Phone.

You should set a limit on the Currently Active Session Count with Active Presence Subscriptions and Currently Active Session Count performance counters based on your expected usage, capacity planning results, and ongoing monitoring of Mobility Service and other Front End Server counters. The limits you set should allow you to evaluate server capacity and raise alerts when capacity is exceeded.

To determine the appropriate limits, you need to first determine how much memory is available on the Front End Server for the Mobility Service. Monitor the counters to determine when you need to plan for extra capacity according to the following formula:

Total memory used by Mobility Service (MB) = 164 + (400 + 134) / 1024 * Currently Active Session Count with Active Presence Subscriptions + 400 / 1024 * (Currently Active Session Count – Currently Active Session Count with Active Presence Subscriptions)

The Front End Server needs enough available memory to support the Mobility Service in failover situations. You can monitor the current available memory on the Front End Server by using the Memory\Available Mbytes counter, or use the equation mentioned previously to plan for the amount of memory that you expect the Mobility Service to use.

If the amount of memory available on the Front End Server is lower than 1,500 MB when you plan for the expected number of mobility users, you need to add more hardware to support the Mobility Service. For more details, see "Scenario Examples" in Capacity Planning for Mobility.