"In the past, our businesses owned their server hardware and applications and had them configured to their individual specific requirements," says Lee Congdon, managing vice president of corporate technology at Capital One. "The result was that we ended up with everything, including Unisys, Tandems, Suns, and AS/400s, you name it. On the software side, we were running Novell NetWare, old versions of [Windows] NT, and Windows 2000."

To tame this unwieldy environment, Capital One began using VMware ESX Server to pack multiple server environments on fewer, more powerful physical servers. Rather than dedicating servers to individual business units, business users are increasingly assigned smaller shares of more powerful processors. "We currently have about 150 server instances running on 17 physical servers," Congdon says. And rather than giving each business its own applications, Capital One has consolidated to five IT-approved platforms. The business units simply buy services, such as knowledge or content management, and often don't even know what platform they're using.

Similarly, Citrix is in the early stages of consolidating 15 racks of 200 out-of-warranty servers to just two racks, or a total of 10 HP ProLiant DL585 four-way, dual-core Opteron servers, using Microsoft Virtual Server 2005 R2. "We'll be saving US$9,000 per month in power costs and huge amounts in network port and cabling costs," says Dimitri Mundarain, Citrix's manager of datacenter operations. Why Microsoft? "VMware's ESX Server is more technically advanced and has a better management console but would be much more expensive in licensing and training costs. Our datacenter runs on Windows, and we like the fact that MS Virtual Server uses the same type of interface."

For other organizations, virtualization is essential to extending the life of datacenters that are close to capacity. "We were running out of air- and power-conditioning capacity, which doesn't scale and is very expensive to replace," says Neal Tisdale, vice president of software development at NewEnergy Associates, a software and energy consulting company. NewEnergy used a combination of VMware GSX Server and Solaris Containers to consolidate its server hardware. The datacenter now runs 19 degrees cooler with no cooling upgrade, Tisdale says; and if the power fails, its batteries can keep it up for days, rather than hours, thanks to the reduced server power load.

Tisdale agrees that VMware is feature-rich but says NewEnergy didn't need many of its features. "We didn't want to drive up cost and complexity by throwing in a lot of enhancements like load balancing and VMotion," he says. "We just wanted to get the heat savings quickly and easily."