Hello Experts,
I am unable to correlate actual guest’s ram usage to values shown in vcops. I took some screenshots,so that it will be easy for me to understand when you explain to me back.
All the below screenshots are taken a the same time almost.
Please help me to understand.
Thank You
Vamsi
Vamsi,
The metrics inside the guest will almost never match up with the metrics shown in the vSphere Client or in vC Ops (and if they do, it's just a lucky coincidence). I explain why in my VMworld talk: http://www.vmworld2009.com/docs/DOC-3817.
What you call "Usage" in the vC Ops screenshot is actually "Demand", which is very close to Guest Active (KB). In fact if you look at the graph of Guest Active (KB), it's floating around 200 MB, which is what the previous screenshot showed.
The metric actually marked as "Usage" in the first vC Ops screenshot (2048 MB) is actually Granted. You're looking at the "Virt" layer. If you look at the "Phys" graph right below there, the "Usage" there is actually Consumed and that should match the Consumed you see in the vSphere Client.
Hope that helps.
What he said.
Kit is probably the best guy to teach you about how memory works in ESX (and vC Ops) and I highly recommend his VMworld memory presentation(s). However, if you don't have the 90 minutes to spare right now, I also wrote a short blog post to help address this question (because I hear it a lot). Hopefully, it helps:
http://www.vkernel.com/reader/items/vsphere-memory-usage-metrics-task-manager
Let us know if you have additional questions.