"This study provides performance comparisons of various storage connection options available to VMware® ESX Server. We used the widely used IOmeter benchmark for the comparison. The results show that all four network storage options can reach wire‐speed throughput when properly configured. The wire‐speed throughput is also maintained with multiple virtual machines driving concurrent I/Os, indicating that the limiting factor in performance scalability is not in ESX Server. The data also demonstrates that, although Fibre Channel has the best performance in throughput, latency, and CPU efficiency among the four options, iSCSI and NFS are also quite capable and may offer a better cost‐to‐performance ratio in certain deployment scenarios."

Of course the conclusion of the paper is that all the four (software and hardware iSCSI) network storage connection options available to ESX Server are all capable of reaching a level of performance limited only by the media and storage devices. And even with multiple virtual machines running concurrently on the same ESX Server host, the high performance is maintained. The data on CPU costs indicates that Fibre Channel and hardware iSCSI are the most CPU efficient, but in cases in which CPU consumption is not a concern, software iSCSI and NFS can also be part of a high‐performance solution.

Comparison of Storage Protocol Performance.