Is a SAN Right for You?

It's best not to think of SANs as being built from any one particular recipe, but instead to think about the list of characteristics your storage deployment requires. Here's a short list of the most important criteria:

• Can you manage with a simple loop or ring network architecture, or do you need to have the flexibility of a fabric architecture? Although it's cheaper to build a loop topology, most people opt to build a switched fabric one.

• Do you require that your storage assets be on their own dedicated network? A SAN with its own dedicated network is what is referred to as an out-of-band network. The LAN that the SAN is connected to is then referred to as the in-band network. The two can be managed independently. While creating and managing two separate networks adds both cost and complexity, there are strong performance and security reasons that make a dual-band network solution a very practical solution.

• How and from where will you manage your storage assets? In a SAN fabric, it is possible to manage your SAN at your server, at the switch, using an appliance, and even with some storage servers at the storage server itself. Many management programs are now browser based. There is no right or wrong answer to this question, but it is part of your guiding philosophy.

• What standards will you choose to embrace? For many years, SANs were recognized as difficult to connect up. Many vendors' devices didn't work with other ones on the market. Because companies tended to create SANs from islands of storage, SANs are often a "Noah's Ark" of servers. It's better nowbut not necessarily easy. There are hard choices to make, ones that require you to make good guesses. Mistakes are very expensive to fix, and many aren't even fixable. This reality causes information technology (IT) managers many sleepless nights and often results in SANs being installed by a single vendora "captive SAN," if you like.

• Are you starting from scratch, or are you integrating existing assets? This criterion speaks to the amount of freedom you have to choose components for your SAN.

• Do you have a budget? A SAN is a major capital acquisition that requires an ongoing commitment. Your budget is your eventual limitation on what is possible.