If you have more than one server connecting to the SAN, you’ll see raw throughput decreased. Also, you will benefit by using an HBA with a TCP/IP offload ASIC onboard, otherwise there is a good chance that your throughput will be throttled at either your processor or your NIC.

I’ve seen situations where DAS is indeed faster… The advantages of SAN storage are many, even if there may be a slight performance hit in day to day usage.

What type of application are you looking at here? Is this messaging? database? general F&P? If you are looking at database storage, make sure you configure your ethernet adapter/HBA to handle data appropriately (you may need to adjust your max frame size).