This is a guest post by Darky from #ESX on EFNet.
A lot of the time an ESX/VI administrator will not always have access to the SAN infrastructure. Often there can be frustration in trying to work with that SAN team cooperatively to determine whether or not the performance issue seen in an ESX environment is ultimately a SAN issue. Today we bring you a KB article that will help you track down and isolate storage performance issues on your SAN by using a lone VM on a single ESX host with an attached RDM which will require very little assistance from the SAN team. By following this KB you can create a baseline I/O metric and then compare that a physical host a equal hardware/OS.