How do I size and stress test my Lync servers?

This is a question I get a lot from my customers. In addition to using the new Lync Server 2010 Planning Tool, we just shipped a few tools to help you with the sizing of your Lync servers whether physical or virtual.

Two new tools have just shipped to help here:

  • Lync Server 2010 Capacity Calculator grab it here

It has some nice flexibility since you can tweak users, calls, conferencing usage, etc:


It will also provide estimates on total number of servers needed and what roles for both physical and virtual (4 core):



How do I stress test my Lync hardware or VM?

Once you buy the hardware and you want to stress it you can use the LyncPerf load tool to stress the following roles:

  • Instant messaging (IM) and presence
  • Audio conferencing
  • Application sharing
  • Voice over IP (VoIP), including public switched telephone network (PSTN) simulation
  • Web Access Client conferencing
  • Microsoft Lync 2010 Attendant
  • Response Groups
  • Distribution list expansion
  • Address book download and address book query
  • E9-1-1 calls and location profile (dial plan)

User creation tool:


You can create groups, contacts for each user:


Create phone DIDs:


You can even create locations for the LIS for E911 testing:


Comes with several PowerShell scripts to populate and configure Lync:


You can create various Lync load files using the User profile generator tool:


You can specify various loads per role:


Different VOIP parameters:



Once you have the config files created. You need to actually run the stress tool from the cmd line with something like this:

RunClient0.bat C:\Program Files\Microsoft Lync Server 2010\LyncStressAndPerfTool\LyncStress 


LyncPerfTool.exe /file:IM_client0.xml /displayfile


There are many performance counters provided for each area of Lync you can look at during or after the test run such as:


Performance Counter


Calls Active

Total number of incoming/outgoing voice calls ongoing currently.

Calls Terminated

Total number of incoming/outgoing voice calls already terminated.

Calls Declined

Total number of incoming voice calls declined.

Incoming/Outgoing Calls Attempted

Total number of incoming/outgoing voice calls attempted.

Incoming/Outgoing Calls Established

Total number of incoming/outgoing voice calls established.

Calls Received NNN

Total number of nnn response code received from the server.

VoIP Pass Rate (%)

Total calls established/Total calls attempted.


  • Lync Server 2010 Stress and Performance Tool grab it here.