Overhead memory vs Overcommitted memory

[Souad90]

In vrops there is no metric for the overcommittment, but there is a metric of overhead. Are they the same ?

[sxnxr]

Overcommit is a capacity management term. It tells you how much you are over the 1:1 relationship between the physical resources (CPU and Memory). This is used in an allocation based model. An example we use a 5:1 CPU overcommit in production so a host with 2 x 10 core processors we can allocate 10 x 2=20 Cores per server x 5 for the overcommit = 50 so each host has a usable vCPU of 50.

Below is a metric that shows the capacity remaining using the over commit ratio specified in my policy for memory (The bottom metric will show me how much memory I have for deployment including my overcommit) This will also take into account any HA buffers specified in the policy as well.

Overhead is what extra resources ESXi uses to host the VMs. Each VM needs a little CPU and Memory on the host that ESXi uses to manage and run it.

What over commit metric are you looking for as there are several. If you use a demand based capacity model you might not see the metric in vrops

[vHaridas]

Memory overhead and  memory over commitments are two different things.

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For each running virtual machine, the system reserves physical memory for the virtual machine’s reservation (if any) and for its virtualization overhead.

Because of the memory management techniques the ESXihost uses, your virtual machines can use more memory than the physical machine (the host) has available. For example, you can have a host with 2GB memory and run four virtual machines with 1GB memory each. In that case, the memory is overcommitted.

Overcommitment makes sense because, typically, some virtual machines are lightly loaded while others are more heavily loaded, and relative activity levels vary over time.

See below URL for memory overhead -

https://pubs.vmware.com/vsphere-4-esx-vcenter/index.jsp?topic=/com.vmware.vsphere.resourcemanagement...

I have not checked what values are vROPS report but these two are different things.