I want to create a pure iSCSI SAN using only Ethernet switches to manage the iSCSI traffic. My question it is about the kind of Ethernet switches I need to use. Of course I'll need to use Gigabit switches, but should they be cut-through or store-and-forward? It is mandatory they support for Jumbo Frames to get the better performance?
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The general answer is that you should be able to use any standard, well-behaved Ethernet switch that supports a Gigabit Ethernet port. Now, that being said, it is also vendor- and product implementation-specific. Check with the manufacturer or systems integrator as to what they will support. Ask your potential vendors which switches they support and why they recommend any particular switch over another. Also ask your vendor or solution provider what their requirements and recommendations are pertaining to isolating SAN traffic from LAN traffic. Regarding whether to use a switch with cut-through routing or store-and-forward, take a look at the latency numbers for the switch along with what your performance criteria are for your application. For storage switching, the low latency and data integrity are very important. The key with jumbo frames and switches is to make sure that your Ethernet adapter or storage NIC, associated driver software and storage subsystem can utilize jumbo frames. You will also want to verify that your Ethernet NIC or storage adapter and storage system and software drivers and switches are all compatible and work together with the switch you are looking at or already using.
This was first published in July 2004