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