Might have stumbled across the answer, as I have just found something similar going on in our environment. I had the RAM increased on a couple of VMs from 8GB to 16GB. Windows reported pretty high memory usage (even though the processes running didn’t appear to be actually using that much), but in vCenter Consumed memory was much lower. I checked the Resources tab for the VMs and found the Memory Limit was set at 8GB rather than having the “unlimited” box checked, which would be normal for a new VM. On checking the box and clicking OK, memory usage in Windows did drop back down to something resembling what vCenter was reporting.
Did a search and found the issue is reported here: http://kb.vmware.com/kb/1003470.
Not happy as going to have to do some checking on 20K+ VMs to see if any of them are also showing a similar configuration.
Tim
