vCenter 5.5 provides 17 counters for storage at the VM level. 7 are new counters compared to vCenter 5.0. The new additions are number of seeks (small, medium, large), latency in microseconds, and size of requests (read latency and write latency). At the VM level, you can look at counters at the individual virtual disk level, datastore level, and disk level:
If you look at the virtual disk counters, you can see VMFS vmdk files, NFS vmdk files, and RDMs. However, you don't get data below the virtual disk layer. For example, if the VM has a snapshot, the data at virtual disk level will know show it. Also, a VM typically has multiple virtual disks (OS drive, swap drive, data drive), so you need to add them manually if you use vCenter. In vRealize Operations, you use the aggregate of all instances.
If you look at the datastore counters, you can see VMFS and NFS, but not RDM. Because snapshots happen at the datastore level, the counter will include it. Datastore...