HP Throws Cold Water on x86 Racks

San Jose, Calif. -- In a throwback to the days of the mainframe, Hewlett-Packard Co. today will announce the first water-cooling system for its X86-based server racks. The company is following in the footsteps of other server vendors, which have been quietly pulling together solutions to the growing heat and power problems found in densely packaged back-end computers.

The HP Modular Cooling System essentially is an 8-inch-wide heat exchanger and blower that bolts onto the company's latest 19-inch rack. It provides a source of cold air to the computer without releasing hot air to the data center, opening the door to racks that include twice as many processors and dissipate as much as 30 kilowatts.

Heat flux, the power dissipation per square centimeter on a server processor, has risen from 10 W to 50 W over the last eight years, or about 7 percent/year, a rate that's expected to continue for the foreseeable future. "It looks fairly linear," said Paul Perez, vice president of storage, networking and infrastructure for HP's In- dustry Standard Servers group.

That means a 19-inch rack of X86 servers that used to dissipate 2,000 W has become a 14-kW rack that will ship this year. Over the next three years or so, X86 server racks will dissipate as much as 60 kW, Perez added.

The density advantages continue to outweigh the heat and power issues. With the new cooling system, users could pack 120 racks into a 3,000-square-foot data center for a facilities cost estimated at $7.8 million. Such a setup would otherwise require 720 racks and 10,000 square feet of floor space at a cost of $16 million, Perez estimated.At the chip level, Intel Corp. and Advanced Micro Devices Inc. are endowing their server chips with the ability to ratchet back CPU frequency when workloads are light and heat becomes an issue.

Looking to the future, "we are starting to deliver a sensor network that could create a real-time map of power and cooling in the data center," said Perez.

He does not expect water cooling to come to the individual server, however, because it would be cost-prohibitive.

Fujitsu, IBM and startup Egenera Inc. (Marlboro, Mass.) have also announced or delivered cooling subsystems for densely packed racks of X86 servers.

Like HP's offering, IBM Corp.'s Cool Blue heat exchanger taps into the chilled-water supply of the existing air-conditioning system in the data center. The IBM subsystem, launched in July, can remove up to 55 percent of the heat generated in a fully populated rack, or about 50,000 BTUs, according to IBM. Pricing for the unit starts at $4,299.Vendors like Sun Microsystems Inc. that have rolled out rack-based systems using aggressively multithreaded, multicore processors will have an edge in terms of power and heat issues, said Nathan Brookwood, analyst with Insight64 (Saratoga, Calif.). But the Sun systems are targeted as midlevel Web and applications servers. Users who need maximum performance will have to deal with the thermal and power implications for some time, he said.

In the long term, "cooling is an easier problem to solve than power distribution and management," HP's Perez said.

HP today will announce a $199 power distribution module that can remotely manage a power subsystem, a job that used to be handled by a dedicated server.

The cooling system will be available Feb. 6 at prices starting at $30,500. It will serve all of HP's rack-mounted X86, Itanium, PA-RISC and storage array systems.