HP’s Project Moonshot shifted focus from the Redstone Server Development Platform based on Calxeda’s ARM processors to a new generation of the Intel Atom System-on-a-Chip (SoC) platform dubbed Centerton.

“It’s the best Atom infrastructure so far, but more significant is the server architecture, with an internal fabric for management of server nodes,” said Forrester Research analyst Richard Fichera. “These very dense x86-based servers put pressure on proposed ARM designs.”

HP emphasized that the new product, called Project Gemini, is not intended to replace any other product in its line. Where RedStone hardware was based on HP’s ProLiant Scalable System SL chassis, Project Gemini introduces a new chassis that connects individual server cartridges to an internal fabric, and those cartridges are to be “processor-neutral,” according to HP.

But in its first iteration, Gemini’s Atom-based processor cartridges will boast several features which appeal to enterprise data centers that its RedStone ARM counterpart doesn’t have, including 64-bit support, error correction code (ECC), enterprise software compatibility, and Intel’s Virtualization Technology (VT) – all in a six-watt power envelope.

Redstone was also referred to by HP in a press conference announcing Gemini on Tuesday as a “market development vehicle,” where Gemini is projected to be a generally available product later this year.

The confluence and competition between ARM and Atom is also being explored by HP rival Dell, which recently floated an ARM-based trial balloon with its Copperhead servers, available only to a select audience.

Meanwhile, microservers, the general category to which all of these products belong, remain suited to a niche market. Microservers pack large numbers of low-power chips into dense chassis and are suited to highly parallelized but lightweight workloads like Hadoop, Web hosting, content delivery, or distributed memory cacheing.

Intel estimates microservers could capture 10% of the overall server market by 2015 and estimates their current penetration at 1-2%. HP predicts 10 to 15% market share for the extreme low-energy servers by 2015.

The 32-bit Advanced RISC Machine (ARM) chips are used widely in cell phones and tablets. They have also begun to appear in microservers such as HP’s Moonshot, based on a partnership with Calxeda, Inc. since November.

At the server level, low-power chips are suited to environments where many relatively lightweight operations such as Web serving must be performed in parallel at massive scale.

Meanwhile, other low-power chips such as Intel Corp.’s Atom have been sold for similar purposes, including microserver startup SeaMicro Inc.’s products prior to the company’s acquisition by AMD. SeaMicro’s products were also resold by Dell.

“That’s a great question,” Dell executive director of marketing Steve Cumings said when asked why an IT pro seeking low-power scale-out hardware would use ARM over Atom or vice versa.

The answer is what Dell is after with the limited shipments of Copper, as well as two test clusters being set up in Dell’s Texas headquarters and at the Texas Advanced Computing Center for remote access by interested parties.

Currently, there’s a lot of code written for consumer devices on ARM, but very little in the way of enterprise applications, which is one thing holding ARM back. Dell also announced it will offer a version of its Crowbar automated server provisioning software on ARM by the end of the year.

The fact that 64-bit ARM designs have yet to hit production is a limiting factor to server-level adoption of the chip. Dell expects ARM servers to be used in production over the next 18 months to two years, when 64-bit chips become commonplace.

The Dell Copper server offers 48 ARM microservers based on the Marvell Armada CPU in a 3U shared environment. Each server node consumes 15 watts and includes Serial Advanced Technology Attachment or Flash storage; up to 8 GB RAM; and a 1 GbE input. Four server nodes are packed into a sled, each of which contains a non-blocking Layer 2 switch, and each chassis contains 12 sleds. The entire chassis draws 750 watts of power.