One of the problems using big disk arrays is the difficulty in getting meaningful reporting out of them. All the vendors’ tools are closed source, and in many cases the expertise from the vendor is often missing or seriously lacking when it comes plotting performance trends.
“Just add more cache” is the same tired refrain vendors always give. No. I’m not going to recommend to clients that they spend a huge sum of money buying more SAN cache until I can prove the SAN actually needs it.
In March 2004 I wrote an article for SysAdmin Magazine showing how to use the symcli command line tools in conjunction with Orca to plot some nice historic performance graphs, showing the host’s view of performance of the Symmetrix array.
You can find the original article, complete with diagrams and code, on SysAdmin Magazine’s website at http://www.samag.com/documents/s=9364/sam0403f/0403f.htm