It is possible that there could be a memory utilization display “mismatch” between vCenter and Task Manager on a given VM if large pages are enabled on an ESX host(s). Just this week, vCenter (working with vSphere hosts) was displaying that the memory utilization of a particular VM was consistently between 95-100%. Looking at the VM itself, it showed less than 37% memory utilization.
I tried removing and reinstall VMware Tools and this seemed to correct the problem for a little while, however, the display mismatch returned. Though performance of the VM was normal, VMware support was contacted to get an official answer on why this situation may occur and if they were aware of this happening on other vSphere servers.
That’s when support suggested disabling the large pages on the ESX host. Below are the steps.
1. Power off the VM which is reporting a high memory usage
2. Turn off large page on the ESX host
a) Select the ESX host from the VI Client
b) Select the configuration tab
c) Under Software select Advanced Settings
d) Select Mem and scroll down till you see “Mem.AllocGuestLargePage”
e) Set the value to 0. By default it is set to 1.
3. Restart the VM and monitor the memory usage
After performing these steps, the memory mismatch problem has not reoccured.