Server virtualization has succeeded because, relatively speaking, it is less disruptive. It doesn't require hardware replacement or new operating systems, and unlike storage, it doesn't require a massive data-migration effort to undo if it doesn't work out. Most importantly, it's largely transparent to applications.

I do believe storage virtualization will get there someday. Unfortunately for many environments, someday is not yet here.

Jim Damoulakis is chief technology officer of GlassHouse Technologies Inc., a leading provider of independent storage services. He can be reached at jimd@glasshouse.com.