Specifications

Best Practices for Virtualizing and Managing Exchange 2013
47
47
Best Practices and Recommendations
Crossing the NUMA boundary can reduce virtual performance by as much as 8 percent. Therefore,
configure a virtual machine to use resources from a single NUMA node.
34
For Exchange Server,
make sure that allocated memory is equal to or smaller than a NUMA boundary.
While setting NUMA node preferences (NUMA node balancing) for virtual machines, ensure that
all virtual machines are not assigned to the same NUMA node. If this happens, the virtual
machines may not get enough CPU time or local memory from the assigned NUMA node.
35
By default, a virtual machine gets its preferred NUMA node every time it runs. However, in due
course, an imbalance in the assignment of NUMA nodes to the virtual machines may occur. This
may happen because each virtual machine has ad hoc memory requirements or because the
virtual machines can be started in any order. Therefore, we recommend that you use Perfmon to
check the NUMA node preference settings for each running virtual machine. The settings can be
checked with the following: \Hyper-V VM Vid Partition (*)\ NumaNodeIndex counter.
Perform NUMA node balancing to automatically change NUMA node assignments, depending on
the requirements of the running virtual machines.
Identify and categorize virtual machines based on the intensity of the loads they bear (high
intensity and low intensity). Then set weights and reserves on the virtual processors accordingly. In
this way, you can ensure that a large amount of the CPU cycle is available for virtual
machines/virtual processors having high-intensity loads.
Install the latest virtual machine Integration Services in each supported guest virtual machine.
Virtual machine Integration Services can help to improve I/O throughput and decrease overall CPU
usage of guests. This is because it includes enlightened drivers for Hyper-V-specific I/O devices
that reduce CPU overhead for I/O.
Exchange 2013 Virtual Machine Memory Considerations
For memory in a virtualized environment, better performance and enhanced support are essential
considerations. You must be able to both quickly allocate memory to virtual machines depending on their
requirements (peak and off-peak loads) and ensure that the memory is not wasted. New enhancements in
Windows Server 2012 help to optimize the utilization of memory allocated to virtual machines.
36
One of
these enhancements is known as Dynamic Memory, which allows Hyper-V to intelligently give and take
memory from a virtual machine while it is running, depending on the demand within that virtual machine
at a given time.