Blade servers are hot. Maybe too hot, according to Dell Computer president and chief operating officer Kevin Rollins. Blades densely packed in a chassis generate excess heat, Rollins warned last week, and potential problems with heat dissipation could stunt growth in the blade-server market.

Blade technology "may not pan out" as well as expected, Rollins said at InformationWeek's Spring Conference. "It's great technology," he said, but concerns are growing about how to cool blades as more powerful, next-generation processors enter the market. "There isn't an obvious solution" to the problem, he said, noting that it's expensive to ventilate and cool densely packed systems. "So the market for blades may be smaller than thought," he added. This would be a blow to the server market, which has not seen much growth in recent years.

	"There isn't an obvious solution" to the problem of keeping blade servers cool, Dell president Rollins says.

Sales of blade servers are expected to increase dramatically, from $341 million this year to $3.7 billion by 2006, according to IDC estimates. The research firm hasn't changed its projections based upon heat-dissipation concerns.

But Rollins isn't alone in his concerns about the technology. "Already the failure rate in the top third of server racks is three times the bottom two-thirds," says Kenneth Brill, executive director of the Uptime Institute, a research and consulting firm that specializes in data-center management. "Blades will further exacerbate this problem." Overheated servers can slow throughput and affect system reliability.

Although Dell and others question the wisdom of running multiple processors in close proximity, Hewlett-Packard last week began shipping a version of ProLiant server blades that's available with as many as four Intel Xeon MP processors. The vendor, which has shipped 15,000 blade servers since the beginning of last year, is positioning the four-way blade to run database, enterprise resource planning, and customer-relationship management applications more efficiently than a standalone four-way server because the blades share electricity, cooling, and power with one another in the 10.5-inch enclosure.

HP's BL40p is specifically designed to support cooling at the blade-server level, HP says. HP Insight Manager 7 software regulates fans and temperature sensors within each blade server and triggers alert notifications if heat thresholds are exceeded.

IBM says it's also addressing the heat issue. It cools its BladeCenter blade servers using fans positioned in the blade chassis that allow for maximum air flow.

Most businesses that are using blades have deployed them in small numbers. The National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign expects to add blade servers to its data center within the next year, although it hasn't yet decided which vendor's it will use. The center wants the advantages of blade servers, which include economical use of rack space and cabling, consolidating server management, and simplifying the process of adding and removing processors.

When it comes to heat dissipation, "we expect the vendors to do their engineering homework," says Robert Pennington, the NCSA's senior associate director for computing and data management. "We would like to see lower-power processors in those servers. These processors from all the vendors run on the hot side today."

But Menasha Corp. isn't going to let a little heat cool its plans to deploy blades. The company is testing a chassis of six Dell PowerEdge 1655MC blades and likes what it sees. "It's a solid technology," says Edward Wojciechowski, CIO of Menasha, a holding company with subsidiaries that make plastics and packaging materials. As the leases on Menasha's dozens of older servers expire, Wojciechowski plans to replace them with blade servers.

Most blades run on Pentium or Xeon processors, though Intel last month disclosed plans to ship a low-voltage version of its Itanium 2 processor aimed at blades in the second half of the year. Code-named Deerfield, the processor sacrifices performance while drawing half the power of Intel's current Itanium 2 processor.