Tuning a SAN for best performance is part of installing the SAN. The usual method is to run loads simulating the customer application and take benchmark measurements to see where performance can be improved.
Before you get to that point, Hewlett Packard suggests using a shortcut that can save some time and effort: Start by baselining the SAN with a simpler, easy to understand load and deal with the issues that baseline test reveals.
Tuning is usually an iterative process, and the first steps generally yield the biggest payoffs. While simulation and successive benchmarking are necessary to get the best performance out of a system, a couple of passes with the much coarser baselining process can often produce fairly large improvements in much less time.
In its discussion, HP suggests running a Unix-based utility as a baselining load (on a Tru64 Unix system) because it is available, easy to configure to test multiple LUNs on the SAN and easy to control.
HP discusses the process in a white paper titled "Best practices to baseline the performance of EVA-based configurations." The discussion is in the context of HP's own products, but the method is applicable to all SANs.
About the author: Rick Cook has been writing about mass storage since the days when the term meant an 80K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last 20 years he has been a freelance writer specializing in storage and other computer issues.