VM Active Memory vs Physical Host memory in vCOPs

Hello, I am looking for explanation on why in vCOPs Host Physical memory is at 90% while VM Active Memory is at only 20%. I am trying to ascertain if we need to add more memory to environment which I believe we do but the active memory indicator is confusing a bit.

Any help explaining possible causes is highly appreciated.

J
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onlinerackAsked:
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Jayanta SarmahCommented:
Active memory utilization is an approximation from hypervisior level or an estimate which may cause this difference as looks like , below are few articles which shall help to understand the memory counters :
https://www.vmware.com/support/developer/vc-sdk/visdk41pubs/ApiReference/memory_counters.html

http://www.yellow-bricks.com/2011/04/29/which-metric-to-use-for-monitoring-memory/

Hope this helps.
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Can you share a screen shot of your Host Summary from the vSphere Client.

More than likely because this is what is Currently Active in the VMs, but what has been allocated is 90%, so if ALL VMs used their memory entitlement, you would be at 90%.

Active versus Granted! (you have given or granted 90% of your host memory to VMs)
onlinerackAuthor Commented:
Thank you you all for your responses. I will try to get a snapshot of the vCOPs.

In the meantime there is a total of 4 TB of physical memory available in a cluster with 3.6 TB "used" by VMs.

Confusingly, Guest Active memory shows less than 1TB  of “Guest active”  is in use by the VM’s even during peak periods.

So I have no explanation to the discrepancy between the two (3.6 TB used by hosts in cluster and less than 1 TB used by all VMs in same cluster)?

J
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
If you run a wastage report, what does it show for efficiency, and can you start to reduce allocated memory to VMs.
onlinerackAuthor Commented:
Efficiency score is 30 in vCOPs. So what does that mean ? Do we use the high utilization rate on hosts on cluster as our baseline for capacity planning or Active Memory on guests? Do we ignore high utilization rate on hosts?
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
You should work on your worst case values, which is your high watermark, which is Allocated.

e.g. if you restarted ALL VMs, they would initially, all consume the memory allocated, until it falls off.

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