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High memory usage by Hyper-V virtual machines

Clients who use WHS plans often ask why a newly installed OS with no software uses 80 to 90 percent of RAM and where this memory is used.

It looks like this:

HyperV high memory usage 1

There are no processes with high memory usage:

HyperV high memory usage 2

This is a normal behavior. This is how the Hyper-V Dynamic Memory mechanism works.

https://technet.microsoft.com/en-us/library/hh831766.aspx

If the virtual machine requires more RAM, the memory will be allocated automatically.

How can I check that the amount of memory specified in the plan is really provided to the virtual machine?​

You can download the RamMap utility from Sysinternals. This company belongs to Microsoft and the utility can be considered a recommended official tool:

https://technet.microsoft.com/en-us/sysinternals/rammap.aspx

https://download.sysinternals.com/files/RAMMap.zip

The amount of memory that is reserved by the virtualization system is displayed as Driver Locked:

HyperV high memory usage 3

How can I find out how much memory the server's processes use in total?​

You can do this using the following PowerShell command (if buffer forwarding is enabled, you can paste the command into the PowerShell console with a right click of the mouse):

Get-Process | measure PM  -sum

You can see that there are 39 running processes, and they use 358,739,968 bytes of RAM, which is approximately 350 MB.

HyperV high memory usage 4

To avoid manual calculations and the risk of an incorrect number of decimal places, you can use the following command:

$mem = 0; Get-Process | %{$mem += $_.pm}; "{0:N2}MB " -f ($mem/1mb)

The result is 340 MB which is consistent with the figure above:

HyperV high memory usage 5