I know there are a number of reasons why vCenter would report memory usage of a vm to be higher than the vm itself reports but I'm seeing situations where vCenter is reporting memory usage several GB higher. Is this normal? One specific vm I'm looking at has 6GB of memory allocated and fully reserved. After a reboot both Windows and vCenter are reporting memory usage right around 1GB. I then open a smallish (~1MB) Excel file. Memory usage in the vm (as reported by Task Manager) jumps to about 1.4 GB but Active Guest Memory in vCenter jumps as high as 5.5GB. At this point the vm is sluggish and scrolling through the Excel document is almost impossible. Closing Excel in the vm will bring the memory usage back down to ~1GB in the vm but has no effect on memory usage reported in vCenter. If I wait about a day Page Sharing will convert all but about 2GB of Active Guest Memory to Shared Memory but the vm performance is still bad. How do I track down what's going wrong? Why is vCenter over-reporting memory usage so dramatically? Why is my vm performance so bad?
I know terms like "sluggish" and "bad" aren't very specific but it's hard to quantify user experience. If there are other metrics that would be helpful in tracking this down I would be happy to collect them.
Thanks for the help!