Warning, rant follows…
I have a problem with referring to a storage array as a SAN as seems commonplace these days. SAN is Storage Area Network. Storage array <> SAN <> RAID <> LUN, but all are related. For clarification, storage arrays, which live in a SAN, typically provide access to LUNs that are often created using RAID technologies to provide data protection.
Everyone has (or at least most of you have) been using SAN and storage array interchangably for years now and that’s not right. I think that the storage vendors are really to blame. When the concept of SANs were introduced, many viewed them as complex, difficult to design/create, and difficult to install. I believe that the storage vendors started selling storage arrays as “SANs” to make them easier to buy and install. I admit that the tools for managing SAN environments have improved to allow a single interface to handle switch zoning, LUN allocation, visualization of the storage configuration and performance monitoring. Technically, putting a storage switch inside a cabinet that includes a storage array does not a SAN make, though many vendors are offering products in that easy-to-buy format these days.
As many expected (including me), there is often very little heterogeneity within SAN environments. That is, when someone purchases their first storage array with multi-host connectivity capability (which many vendors refer to as a “SAN”), they often will purchase another product from the same vendor so as to maintain compatibility with the tools they have already deployed to maintain the storage array(s). That makes good sense–as long as it makes sense for your business.
I ask that next time you think about buying “a SAN”, ask the vendor what you call the thing you’re buying when you add another similar device to the same storage network. Are they each a “SAN”? At that point, the SAN becomes the network of all storage devices in your enterprise instead of the SAN-in-a-box that they’re selling you today. When Ethernet first started becoming widespread, you didn’t buy a network–you built it using switches, hubs, routers, etc. SAN terminology should be used correspondingly, just adding storage arrays to the list of devices that comprise the SAN. Try pointing to your data network sometime…can’t do it, can you? I maintain that you shouldn’t be pointing to a storage array and calling it a SAN. In fact, you shouldn’t be pointing to anything (except perhaps a diagram depicting the whole environment) and call it the SAN.
Okay, I’m done. I really don’t know why I’m so frustrated by the term SAN and its misuse, but my feelings (apparently) are more than a passing thought as I find myself correcting people in almost everyone conversation that comes up on the topic. Ever see the Conspiracy Theory movie where Jerry Fletcher has to buy copies of The Catcher In The Rye whenever he sees them and he doesn’t know why? That’s sort of what this is like, except I’m a little less nuts than Jerry.