To improve the I/O performance for ESX Virtual Infrastructure, VMware had come out with the round robin option for both ESX and VM guests. Although is an experimental option in the ESX setting today, but I will encourage you all to try this option which provide fail over and load balancing on the storage path to connect to you SAN storage. For VM guests, you will allow allow to use this when you have RDM – Raw Device Mapping option to direct read write to the physical LUN from your SAN storage without using VMFS.

Read more »