What Is SAN Topology?

SANs are not just for the birds. They're also for the IT guys and gals who must manage them. If you're going to be a storage administrator, you have to know your way around a SAN, which means understanding their different topologies. A SAN is a storage area network, which means it's a way of connecting multiple computers to share information and data. In concept, a fabric is identical to a network segment in a local area network (LAN). A standard fiber channel SAN fabric consists of several fiber channel switches. The connections between these switches are called "links." The combination of links and buttons is called a fabric. The controls in the fabric exchange information about the location of attached storage devices, and the links carry this information between them. There are three main types of SAN topologies: point-to-point, arbitrated loop, and fabric. Each has its strengths and weaknesses, depending on your system's size and what you need it for. The best way to think about SAN topology is like a wedding cake—you have some tiers, and each tier has its unique flavor. The first tier is your edge switches, the delicious icing on your cake. You can have as many of these as you want, but they will all be quick and easy to manage because they don't have any extra layers between them and the devices they connect. The next tier is your core switches, like your cake's filling: sweet and gooey but not as exciting as the cake part. These switches are where most of the traffic gets routed through, so it makes sense to have more of them than edge switches—but not too many! Finally, there's your storage array itself. This one doesn't change much from topology to topology—it's just there to hold all those delicious files you'll eventually access from one of your happier clients!