Despite this fairly rapid penetration, the technology still has some maturing to do, and some vendors are not yet fully on board. Others question the staying power of blade servers.

"Blades in the enterprise are dead; they are over-promised and under-delivered," says Michael McNerney, director of blades marketing, Systems Group at Sun Microsystems. "Extreme density and cable consolidation are nice to have, but with today's blade architecture, they come at the cost of sub-optimal performance and increased cost and complexity."

HP, on the other hand, is enthusiastic about the future of blades.

"HP envisions the future of blades as an environment where everything — not just servers — can be bladed," says Mark Potter, vice president HP BladeSystem. "The HP concept of designing a blade infrastructure where everything is bladed will have profound implications for how customers implement technologies throughout their organizations."

Gartner research director Jane Wright believes the truth lies somewhere between those two extremes. Rackmount servers, she says, are still better for most applications. She cites three key reasons for switching from rackmount to blade servers:

• High performance computing (HPC) clusters — HPC clients with clusters, when replacing aging rackmount equipment, are switching to blades to achieve greater density.
• Web applications — This includes external facing customer applications, as well as services provided to mobile employees or those accessing the wireless networks. These types of applications run well on small Windows or Linux blade servers.
• Cost — In some instances, customers can save money by filling up a chassis with blades and then sharing the networking and storage.

Further fueling the growth is that earlier problems with cooling seem to have been addressed.

"Two years ago when I would speak to clients on the phone, I would regularly hear of blade servers overheating and shutting down," says Wright. "Lately I haven't been hearing that."

She attributes this to vendors improving cooling designs and switching to more efficient dual core or Opteron processors as well as customers managing their expectations for how much density they can realistically achieve.

"Customers have helped by seeing that they can't fill a whole rack with blades," she says. "They are still filling the blade chassis, but they are only putting about three chassis in a rack."

Blades may not be appropriate in all cases, however. Although Garner expects blade penetration to continue to rise, it doesn't foresee them occupying more than 20 percent of server real estate in the data center by 2010.

Most of the major server vendors have a server blade offering. IBM, for example, released a new enclosure called BladeCenter H in February. It supports 4X InfiniBand and 10 Gb Ethernet. Other blade products include Dell's PowerEdge 1855, which holds up to 10 Xeon-based blades in a 7U enclosure, and a recently released blade from Fujitsu that holds up to eight dual-core Opterons on a single blade.

HP's BladeSystem integrates the hardware, management, virtualization, and services. This enables customers to deploy multiple CPU and I/O generations, rather than upgrading the entire setup.

"The key to this fully bladed future is standards," says Potter. "HP's standards-based approach will offer unified management and consistent interconnectivity so blades can be deployed across the data canter with even greater efficiency and ease."

To address the power and cooling issues associated with blades, HP is releasing a new infrastructure this summer that will incorporate a new fan design. Called the HP Active Cool Fan, its design is based on radio-controlled airplane engines.

"HP research has found that for every dollar spent on IT in the data center, companies spend a dollar or more to power and cool that equipment," says Potter. "Not only does the fan consume one-third of the power of existing fans (drastically reducing energy consumption), but it is 50 percent more effective in cooling."

Sun is perhaps the only remaining major vendor not on the blade bandwagon. Although it offers a line of blades for OEMs to use in carrier-grade, high-availability telecommunications applications, for data center applications it is sticking with rackmount until blade technology matures.

"With the economies of scale in enterprise computing, blades need to either be broadly accepted or die off," says McNerney. "We believe the performance, price, and flexibility found in rackmount servers today will continue to dominate until a better solution comes to market."

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