SAN switches are the fabric of a storage network: Fibre Channel switches that connect servers to shared storage with the low, predictable latency block storage demands, entry switches for a first SAN, and the director-class and expandable models that carry a data center's storage traffic. If servers share an array, a pair of these sits in the middle.
Design in pairs - production SAN fabrics run two independent switches so no single failure strands storage, and every server and array connects to both. Size by port count with genuine headroom, since fabrics grow by attaching things, and check that the switch speed matches the HBAs and array ports it will link; a fabric runs at the speed of its slowest negotiated link. Licensing often gates ports and features, so confirm what is enabled versus what is physically present. COLAMCO quotes SAN switching with the servers, HBAs, and storage it connects for business, government, and education data centers.