VM memory usage:

[john23]

Hi All,

In one of client environment they have following VM:

-128 GB memory assigned to vm ( Host has 256 GB memory, no over commitment)

-Running SQL and Reserve memory inside the Windows OS for SQL instance (no memory reservation on VM level)

As I see the active memory usage it is showing only 10%.

My Question is: If we reserve memory for application inside the OS, at VM level will it show the active memory usage for 128 GB or 28 GB.

As per my understanding, it should show for 128 GB, since inside the OS at application level reservation, vCenter will never capture.

Please correct me, if I am wrong. Please provide any reference doc as well

-Thanks

A

[weinstein5]

Active memory shows memory that is being actively used by the guest OS and its applications so even if you reserve all 128 GB in the OS if it is not being used it will not be recognized by vCenter - at least that is my understanding

[john23]

Weinstein,

Can you provide some reference doc or white paper, it would be helpful, Since I explained same stuff to my client. Still he is looking for pointers.

Thanks

-A

[john23 · Accepted solution]

Use the Active memory counter from vSphere with caution. Active memory is the amount of memory

that’s currently being used by the guest operating system and its applications. SQL Server does its

own caching and memory management, so the Active memory counter might not accurately reflect

the memory consumption of an SQL Server workload. You should always confirm memory usage of

an SQL Server virtual machine by checking memory counters within the guest operating system.

http://www.vmware.com/files/pdf/solutions/SQL_Server_on_VMware-Best_Practices_Guide.pdf

In SQL case we need to check mem counters as per this white paper