The server boards can be swapped out for small form factor, 2.5-inch hard drives, or for solid-state drives, for customers that want more storage instead of compute power.
Keels claimed a half rack of the Calxeda servers can do as much work as 10 racks of two-socket x86 servers, when running certain applications including Hadoop or the Apache Web server. But the Calxeda servers draw only 9 kilowatts, or one-tenth the power of the x86 servers, according to Keels.
HP isn't alone in building efficient servers for "hyperscale" environments. SeaMicro sells a 10U server called the SM10000 that has 512 Intel Atom cores and uses some of the same shared infrastructure principles as HP's Redstone. And Dell builds servers for big customers using a variety of low-power processors, and has said it is experimenting with ARM chips.
ARM-based servers face several challenges, however. There's no 64-bit ARM processor today, which limits the amount of memory HP's servers will be able to address, and hence the types of applications they will be able to run. ARM just announced its first 64-bit design, but its not expected in systems until 2014.
Being 32-bit-only also limits what 's already a fairly small pool of server software options. A version of Red Hat's Fedora Linux is available for 32-bit ARM processors, Keels said, and Canonical has said it will do a 32-bit version Ubuntu for ARM, he said.
Those limitations mean that for most customers, more traditional x86 servers will remain the dominant platform for some time.
"We aren't slowing down at all on our traditional x86 environments, which will continue to be the workhorses of our data centers well throughout the rest of the decade," Keels said.
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