Specifications

Best Practices for Virtualizing and Managing Exchange 2013
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Windows Server 2012 Hyper-V, the default virtual NUMA topology is optimized to match the NUMA
topology of the host/physical computer, as shown in Figure 27.
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Figure 27: Guest NUMA topology by default matching host NUMA topology
The best practices below provide more guidance around managing varying CPU demand, reducing
overhead on the CPU, and optimizing processor performance for Exchange workloads.
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Best Practices and Recommendations
Hyper-V publishes performance counters like Performance Monitor (Perfmon.exe) and
Logman.exe. These performance counters help to characterize the behavior of the virtualization
server and report resource usage. To measure CPU usage of the physical host, use the Hyper-V
Hypervisor Logical Processor performance counters. The Performance Tuning Guidelines for
Windows Server 2012 contain the list of available performance counters.
Do not oversubscribe the CPU for any virtual machine that you use in an Exchange 2013
infrastructure. Use a VP:LP ratio of 1:1 for optimum performance, but 2:1 is supported.
For any virtual machine that is running Exchange 2013 roles, detailed and accurate capacity
planning and sizing should be performed. This is to determine the correct amount of
processors/cores or, in this case, the minimum number of virtual CPUs that should be assigned to
the Exchange virtual machine. This value should be based on published guidance from the
Exchange team, such as that found on TechNet or the Exchange Team Blog on Sizing. The
Exchange 2013 Server Role Requirements Calculator also provides helpful guidance.
Although Exchange 2013 is not NUMA-aware, it takes advantage of the Windows scheduler
algorithms that keep threads isolated to particular NUMA nodes; however, Exchange 2013
does not use NUMA topology information.