First will come virtualisation, then utility storage. That's long been the vision of how enterprise storage will evolve as IT grows increasingly dynamic and on-demand becomes business as usual.

The good news is that storage virtualisation's day finally has arrived, the uptick in interest fueled by the success of server virtualisation and reports of noteworthy results from early adopters. Pioneers cite big gains in storage utilisation and decreases in device-level management headaches. They also share how they've avoided the spending sinkhole despite contending with ever-increasing data volumes.

"We've gone from 40-percent utilisation of storage on the back end to up over 85 percent. Virtualisation has saved us from going out and getting three times more disk than we needed, and we've realised a single point to manage connectivity between storage and the hosts," says Drew Kreisa, storage administrator at Mercury Marine, a recreational propulsion-engine maker in Fond du Lac, Wis.

Early adopters also have discovered, however, that the distance between storage virtualisation and a utility-storage utopia is vast and full of what seem to be insurmountable challenges. Confusion - about the large number of architectural options, the lack of interoperability among different vendors' products and poor storage-resource management (SRM) tools for virtual environments - has muddied user expectations. As they wait for the industry to sort itself out, IT executives are left to relish the gains storage virtualisation has brought them while pushing off their grand utility visions further into the future.

The wow of now When Mercury Marine started looking at storage virtualisation options five years ago, choices were limited. Not so today. The options for how to architect the abstraction of the physical layer are so abundant that IT executives should be wary, Kreisa says.

"There's a lot of confusion in the market. There are too many companies offering completely different ways to architect your network, which means you have to be careful not to bring a new component into your network that will blow away what you're already doing," he says.