While attending NetApp training they told us that NFS performance is better than FC when using many VMs on a host because latency is
lower.
Here are the slides they showed:
Still, I'm not sure I'm buying these statements just like that... VMware has also done some metering of the different storage protocols and there FC is clearly much faster than the other protocols, even when running many VMs. VMware is measuring throughput instead of latency so the numbers are not directly comparable:
I did some testing back at VMworld 2006 in a lab where we compared storage performance in the different protocols and got similar throughput results as those from the VMware paper above (FC 2x as fast as NFS/iSCSI). Latency is of course an important factor here as well, but I would imagine that latency over FC would typically be quite a bit lower than one transported over IP (atleast if you don't count in FCOE with enterprise 10GbE switches). The storage used in that lab was also provided by NetApp.
Lars
