Are disk I/O performance metrics available for virtual disks?
The vSphere 4 SDK documentation leads me to believe that they should be. A quote from the "Disk I/O Counters" section:
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.
However, when I request disk metrics for a VM, via QueryPerf(), the instances I get back seem to be associated with the VM's datastore, not its virtual disks.
For example:
For the metricId I set the counterId to 131076 (disk numberRead) and the Instance to "*".
The intervalId is set to 20 (real time) and the entity is set to the MOR of the VM in question.
The call does return a set of metrics, but the instanceId comes back as something like: t10.E4143500000000000000000010000000E011000000000100, which corresponds directly with the ID of the LUN on which the VM's datastore is based.
Even if the VM has multiple virtual disks and each is on a different datastore, I only get one set of metrics.
Is this the expected behavior or am I doing something wrong?
Thanks
