Storage virtualization hit the scene a few years ago, initially from a small group of start-ups. At first, the concept seemed straightforward, provided you took the time for a few demos. After some high-powered marketing and evangelizing from a couple of those early players, and lip service from larger vendors that have yet to deliver their virtualization products, everybody seemed to be on the same page regarding virtualization.
Then came the calls from StorageTek, saying, "Wait just a minute: We invented virtual disk." And they were right. They did invent virtual disk in the context of a high-end mainframe disk array. But that use of the word is a far cry from what those early storage area network (SAN) virtualization vendors were talking about. (For one thing, virtual disk technology only works on STK's architecture; it does not virtualize heterogeneous storage arrays.)
Next, vendors with software that looked suspiciously like good old hierarchical storage management started referring to their code as virtualization software. And they, too, were correct. It virtualized different storage device types. But, again, it wasn't the same thing as SAN virtualization and virtualization appliances.
The result: Confusion among end users, which inevitably leads to stalled adoption, all because of some logomachy perpetrated by a few vendors trying to capitalize on a cool buzzword.
What's a SAN?
The trade press also jumped all over SANs in the early days, with cutesy headlines such as: "It's SANtastic!" "It's a SANaganza!" Then came "It's time for a SANity check."
Vendors loved the term, too, leading to companies such as SANavigator, SANcastle, SAN Valley, etc.
It was a good term for a good technology that solved some problems for end users, although I would argue that it wasn't really new. SANs existed in the mainframe world in the previous decade, not to mention VAXclusters-but don't get me started.
Over time, SANs became synonymous with Fibre Channel, which was the only enabling game in town. But still there was confusion among end users because wasn't network-attached storage (NAS) a storage network?
Then came the concept of IP SANs and the iSCSI alternative to Fibre Channel (at least at the low end). Some iSCSI proponents prefer to drop the SAN acronym altogether (because of the perceived stigma attached to Fibre Channel), referring instead to their solutions as IP storage networks. But this doesn't do much to distinguish it from NAS (unless you go down the file-versus-block argument).
Again, the result is end-user confusion. (Remember those early polls that asked, "Do you have a storage area network?" I'll bet that among those responding "Yes," a large percentage actually had NAS. Keep that in mind when vendors tell you that 25% of IT organizations have storage networks.)
The best chance for straightening out the definitions is for a storage-specific organization such as the Storage Networking Industry Association (SNIA) to clear up the confusion-which, in fact, is one of its many goals.
SNIA On Storage
This month, we begin a regular series of columns from SNIA. The main reason we started this was to engage the end-user and integrator communities (our readers) more actively in SNIA activities. Although SNIA is primarily a vendor organization, the result of its work should be for the good of the consumer (end-user) community. But that will only happen if you get involved. So, visit www.snia.org. Get involved.
Next month, our SNIA On Storage installment will focus on virtualization.