The disk group of counters support metrics for I/O (input/output) performance (such as latency and read- and write-speeds), and utilization metrics for storage as a finite resource. This page includes documentation for disk I/O performance counters only. See Storage Utilization Counters page for information about storage capacity counters.
Disk-I/O counters support metrics for both physical devices and virtual devices:
- A host reads data from a LUN (logical unit number) associated with the physical storage media.
- A virtual machine reads data from a virtual disk, which is the virtual hardware presented to the Guest OS running on the virtual machine. The virtual disk is a file in VMDK format.
Taken from Disk Counters [Disk I/o Counters] i think it is still valid
