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I have a Windows 2008 R2 64 bit virtual machine on ESXi 4.1 host. The host reports that the virtual machine is actively using less than 1 GB of memory. But, in Windows it's reporting the machine is using 7 GB of memory, even though the total of the processes listed in task manager is less than 1 GB. The machine is rather unresponsive and I'm concerned this is impacting other applications (server's purpose is to run ASP.NET state server process, which has been having trouble and led me to spot the memory question).

I just noticed High memory usage Windows Server 2008r2 on VMware and will be looking through those documents more, but what is causing this?

vSphere report

windows report

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Don't give a virtual machine more memory than you want it to use. the OS assumes that it's "free" to use memory and will use pretty much all you assign it whether it needs it or not. – David Schwartz Aug 16 '12 at 21:23
But, what is using it? Within Windows, it is unclear what process is consuming it. Using task manager and process explorer offered no clues. – RyanW Aug 16 '12 at 21:34
Check with perfmon. – HopelessN00b Aug 16 '12 at 21:38
You have much of the data in front of you. What does this server do? – uSlackr Aug 16 '12 at 21:41
It's only responsible for ASP.NET state server, which is using about 120 MB. All other processes are less than 100 MB, and most are quite small. Total (as listed in task manager and process explorer) is nowhere near 7 GB. – RyanW Aug 16 '12 at 21:46
up vote 3 down vote accepted

You can run RAMMap in the vm to find out how Windows is using the memory.

If Windows isn't under memory pressure, it doesn't bother to make any memory free, so memory can accumulate that is technically used but not really used. The OS assumes that there is zero cost associated with memory that is used if there's still enough available memory to meet foreseeable demand.

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RAMMap reports that about 5.5 GB is "driver locked" which seems to be VMWare probably from what I've read about their memory management. – RyanW Aug 17 '12 at 17:43
Ahh, so probably VMWare is stealing it from Windows to give back to Windows when it thinks it needs it. That's probably how they get around the "Windows thinks it's free to use RAM" issue. – David Schwartz Aug 17 '12 at 21:28

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