According to Forrester, as of Q2 2008, server and client virtualization is mature enough to pay off in the short term, but storage virtualization—particularly application storage—is "not very advanced" and doesn't yet offer much payback.

Application storage virtualization, which is offered by EMC, IBM, HP and Oracle, is still taking its first steps, available only in alpha versions. Forrester Analyst Galen Schreck says in the report that at this early point, its value is questionable, given that the technology only offers "basic tiering and thin provisioning" that customers can already get from more mature forms of storage virtualization.

Oracle Database is one basic example of early application storage virtualization. It's capable of managing and virtualizing raw disk using the application's own file system. Forrester believes that other vendors are also working on such capabilities, which will allow applications to make sophisticated policy decisions about where their content is stored.

Give it three to five years, Forrester suggests, during which time application storage virtualization will work itself into major application platforms that have long refresh cycles. When it's good and ripe, though, the technology is poised for "significant success," the report concludes.

Application storage virtualization was one of 17 virtualization technologies Forrester looked at for the report, and it was the only one that the analyst firm slotted into its "Creation Phase."

Some other virtualization technologies that Forrester thinks aren't yet ready for prime time, but which Forrester categorizes as having clawed their way up to becoming "Survival Phase" technologies:

* Network performance. "Services for enhancing network performance have not been that widely deployed, limiting their overall business value. Today, they are typically found in busy Web application environments but rarely in the rest of the network infrastructure," Schreck says in the report. Within three to five years, this technology will take off, he said, since it will produce "strong and measurable ROI" by allowing applications to work better with less infrastructure.

* Network security. The main benefit of virtualized network security is in avoiding the need to purchase a new security appliance for each new application, but most organizations haven't implemented this type of pervasive security, Forrester says. With big security and networking vendors ready to deliver within the year, mainstream adoption is near, but Forrester thinks the promise of instantly delivered pervasive security services is only going to have moderate success. "Most firms have not migrated from a heavily protected perimeter to a more pervasive security," Schreck writes.