-- Offer a clear payback.

It also doesn't hurt to have a loyal and vocal chorus of successful early adopters.

While server virtualization meets all of these criteria, storage virtualization unfortunately doesn't -- at least not yet. While the potential value is easy to understand, technical maturity and the potential for savings remain cloudy.

Just to be clear, while there is lots of virtualization within arrays, I'm referring to storage virtualization at the network layer. A handful of products have evolved over several generations and developed market niches providing specific functions, most notably data migration and network-attached storage global namespaces. Others still mainly offer future promises.

Depending on the environment, virtualization can either reduce or add to the level of management complexity. Concern with finger-pointing and vendor nonsupport of virtualized configurations is another problem. Confusion over competing technology approaches, lack of standards and fear of vendor lock-in are additional deterrents.