Hewlett-Packard is developing servers based on a low-power microprocessor design from ARM Holdings, and claims it can slash power and space requirements by as much as 90% for companies running certain Web-based applications, HP announced Tuesday. The servers use a 32-bit processor from ARM licensee Calxeda, and are aimed at web giants such as Yahoo and Facebook, as well as other companies running large-scale cloud applications for tasks like data analysis, web serving and content delivery. HP\'s server design packs 288 Calxeda chips into a 4U rack-mount server, or 2,800 in a full rack, with a shared power, cooling and management infrastructure. By eliminating much of the cabling and switching devices used in traditional servers, and using the low-power ARM processors, HP says it can reduce both power and space requirements dramatically. It will release its first ARM servers in the first half of next year, said Glenn Keels, director of marketing for HP\'s Hyperscale Business Unit. However, they\'ll be for testing and evaluation purposes only, he said, and HP isn\'t saying yet when it expects to sell ARM-based servers for production use. \"We want to get the technology out there so that people can start testing their applications for suitability,\" Keels said. Still, it\'s a big step for HP, which becomes the first major vendor to announce an ARM-based server. It\'s also significant for Calxeda, a startup from Austin, Texas, that\'s been developing its technology in secret and has yet to even announce its first product. But Tuesday\'s news is about more than a new server, Keels said. The Calxeda system will be the first in a family of energy-efficient servers that HP will release for \"hyperscale\" customers using a new platform it developed called the Redstone Server Development Platform. In addition to the Calxeda product, HP will develop further Redstone servers using low-power chips from other vendors, including Intel\'s Atom processor, Keels said. \"This is about much more than a server,\" he said. \"It\'s an infrastructure, its a customer enablement program, and its about uniting industry partners behind a vision for extreme energy efficiency that will evolve in the coming quarters and the coming years.\" HP will ship its first ARM system to only 30 or 40 of its biggest customers for testing, Keels said. Other customers will be able to visit HP labs in the U.S., China and France to try out their applications and see if they scale efficiently on the new hardware. The Redstone platform uses a 4U (7-inch) rack-mount server chassis. Inside, HP has put 72 small server boards, each with four Calxeda processors, 4GB of RAM and 4MB of L2 cache. Each processor, based on the ARM Cortex-A9 design, runs at 1.4GHz and has its own 80 gigabit cross-bar switch built into the chip