Utility computing, a much-hyped vision of the future of enterprise computing, is finally coming into focus. For years, full-service technology vendors such as Hewlett-Packard, IBM, and Sun Microsystems have touted a future in which all the components in a data center coexist in a flexible fabric that lets business-technology managers allocate and reallocate server capacity, storage capacity, network bandwidth, and other resources as needed. They're beginning to offer pieces of that vision, and some customers are starting to test whether the concept delivers the promised benefits.

Still, despite the appeal of providing users with computing power in the same way they get electricity and phone service, it won't be easy to transform the silos of disconnected IT systems that exist in most companies into one cohesive utility that offers computing services through a plug in the wall or over a wireless connection. Much of the necessary technology isn't yet available, especially for businesses that don't want to outsource their IT operations.

Most technology vendors hope to get customers moving down that path by helping them tie together data-center elements in more manageable pieces--a set of departmental servers or storage area networks, for example.

Some go so far as to compare this new breed of data center with a living organism. Forrester Research refers to the utility computing model as "Organic IT," consisting of integrated networks, servers, software, and storage so that each of these resources can be used when and where they're needed. "Organic IT is on the same order of magnitude as client-server computing was," Forrester principal analyst Frank Gillett says. "It's starting a 10-year run that will cut data-center costs in half."

Gillett estimates that a company can save more than $2 million over five years by dynamically provisioning server capacity. Similarly, a company can cut storage costs by more than $3 million over five years through storage virtualization. Add in networking and software savings, and Forrester says Organic IT savings could reach nearly $11 million in five years.

HP, IBM, and Sun are the three key vendors in the Organic IT market, according to Forrester. HP offers its Adaptive Infrastructure strategy primarily through its Utility Data Center products. IBM touts its On-Demand outsourcing and "autonomic" self-regulating and self-healing data-center technology. And Sun pushes its N1 hardware, software, and services combination as the foundation for utility-based data centers.

Other technology vendors are looking to play a role in the emerging utility-computing market. Microsoft in March introduced its Dynamic Systems Initiative, a soft- ware-architecture and application development approach to running data centers with minimal human intervention. The first set of technologies to support the initiative are integrated in the Windows Server 2003 operating system, with additional development tools, apps, and management products scheduled to ship over the next few years.

In addition to the packages that HP, IBM, Microsoft, and Sun plan to deliver, IT departments also will have the option of pulling together their own combination of technologies from smaller vendors. Such technologies include grid, routing and switching software, and appliances that let IT managers pool network, server, and storage resources. Think Dynamics Inc.'s ThinkControl software, for example, can be used in conjunction with switching devices to tie together data-center resources, such as storage, input/output, and servers via Ethernet, Fibre Channel, or InfiniBand. Topspin Communications Inc. offers a switched-computing appliance that lets companies run IT operations as a utility by routing terabytes of information through their data centers at 10-Gbit speeds. Such technology can be used to cluster databases. Another company, Platform Computing Inc., offers software to help companies pull data-center resources into a grid configuration.

The three major vendors--HP, IBM, and Sun--all sell servers with extra processors that can be turned on at a later date to handle growing workloads. But the key to making utility computing work is software.

Today, HP's Adaptive Infrastructure model is more advanced than offerings from other large competitors, analyst Gillett says. At the core of Adaptive Infrastructure is HP's Utility Data Center, a rack-mounted server that comes with the software needed to manage the data-center environment. The UDC Management Rack, available since November 2001, includes Intel and PA-RISC processors to control a data center's servers, storage, and networking equipment. The rack starts at about $500,000. Each rack can manage about 600 devices, or nodes, and companies can link up to 100 racks in a single data center.