First physical drives matter. If you have 20 logical drives on the SAN that all are built on the same physical drives, you aren't helping.

You have to clarify what you mean by physical drives. Are these drives located inside the server machine? Typically these are DASD (direct attached storage device) as opposed to SAN, which is a network device.

If you can get your data onto more physical drives, usually in a series of R1 or R10 arrays, performance often improves, but you should have some metrics that show what performance is now, and how a new configuration might imrpove that.