Q. What are the new performance counters in Hyper-V R2 SP1 that measure dynamic memory?

A. Adding SP1 to a Hyper-V R2 server adds the new dynamic memory feature. I talk more about how this feature works in this question.

But, as you can imagine, to figure out how much memory a virtual machine (VM) requires, you'll need monitoring data. That monitoring data provides information to the memory balancer that lets it make decisions about which VMs need more or less RAM.

Thankfully, that monitoring data is also exposed to a Hyper-V host's user interface inside PerfMon. Two counter groups are available. The first, Hyper-V Dynamic Memory Balancer provides host-level information about the behaviors of the memory balancer itself. That counter group has six counters:

Each running VM will also provide information into the second counter group, Hyper-V Dynamic Memory VM. This counter group provides information to the memory balancer function that enables it to accomplish its tasks. Ten counters are present in this group:

While this information is intended primarily for consumption by the memory balancer, it can also provide useful data about how your VMs are processing their workloads.

For example, if your numbers of Memory Add Operations and Memory Remove Operations are high, this means that the level of memory use by that VM is seeing a high level of change. This can be occurring due to processes that are starting and stopping, or processes that are routinely requiring different levels of memory for their tasks.

Catch up with @ConcentratdGreg on Twitter!