I'm not 100% sure about it, but I really think that the disk performance ir related with the fact that iSCSI/FC access disks using an specific VMHBA, which is able to get the numbers needed to measure performance. NFS is a simple mount operation, and do not involve any measurable HBA device.

Marcelo Soares

VMWare Certified Professional 310/410

Technical Support Engineer

Linux Server Senior Administrator