VM Memory - Consumed Host memory

[Shivaprabhu]

When I select the VM, under the summary tab I could see the below 2 memory related values,

Consumed Host Memory

Active guest memory

Noticed that most of the VMs Consumed Host Memory is more/equal (some times less) to allocated memory. Below is the example,

TestVM:

Allocated Memory: 8 GB

OS: Windows 2012

Consumed Host Memory: 7.8 GB

Active Guest memory: 819 MB

It would be great if someone can help me to understand the Consumed Host Memory.

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Regards,

Shiva

[sk84 · Accepted solution]

Consumed Host Memory is the amount of memory that the ESXi host has assigned to the VM (including overhead). Or in other words: The amount of memory that the virtual machine has requested from the ESXi host. In many cases, this value is close to the configured VM memory size, since modern operating systems allocate a large portion of the available memory and use it for buffering IO blocks, for example, when applications do not need all the available memory. This accelerates applications because RAM is faster than disks. The value can even be greater than the VM's configured memory limit, as it also contains overhead.

Active Guest Memory is the part of Consumed Host Memory that is actually actively used within a certain time. For this the memory is divided into memory pages (I think they are 4KB each) and the hypervisor checks how many of these pages were actively used in a certain sampling period.

[Shivaprabhu]

Thanks a lot for quick response.