In late 2010 I noted that startup SeaMicro had introduced an ultra-dense server using Intel Atom chips in an innovative fabric-based architecture that allowed them to factor out much of the power overhead from a large multi-CPU server ( http://blogs.forrester.com/richard_fichera/10-09-21-little_servers_big_applications_intel_developer_forum). Along with many observers, I noted that the original SeaMicro server was well-suited to many light-weight edge processing tasks, but that the system would not support more traditional compute-intensive tasks due to the performance of the Atom core. I was, however, quite taken with the basic architecture, which uses a proprietary high-speed (1.28 Tb/s) 3D mesh interconnect to allow the CPU cores to share network, BIOS and disk resources that are normally replicated on a per-server in conventional designs, with commensurate reductions in power and an increase in density.

Calxeda, one of the most visible stealth mode startups in the industry, has finally given us an initial peek at the first iteration of its server plans, and they both meet our inflated expectations from this ARM server startup and validate some of the initial claims of ARM proponents.

While still holding their actual delivery dates and details of specifications close to their vest, Calxeda did reveal the following cards from their hand:

• The first reference design, which will be provided to OEM partners as well as delivered directly to selected end users and developers, will be based on an ARM Cortex A9 quad-core SOC design.
• The SOC, as Calxeda will demonstrate with one of its reference designs, will enable OEMs to design servers as dense as 120 ARM quad-core nodes (480 cores) in a 2U enclosure, with an average consumption of about 5 watts per node (1.25 watts per core) including DRAM.
• While not forthcoming with details about the performance, topology or protocols, the SOC will contain an embedded fabric for the individual quad-core SOC servers to communicate with each other.
• Most significantly for prospective users, Calxeda is claiming, and has some convincing models to back up these claims, that they will provide a performance advantage of 5X to 10X the performance/watt and (even higher when price is factored in for a metric of performance/watt/$) of any products they expect to see when they bring the product to market.

From nothing more than an outlandish speculation, the prospects for a new entrant into the volume Linux and Windows server space have suddenly become much more concrete, culminating in an immense buzz at CES as numerous players, including NVIDIA and Microsoft, stoked the fires with innuendo, announcements, and demos.

Consumers of x86 servers are always on the lookout for faster, cheaper, and more power-efficient servers. In the event that they can’t get all three, the combination of cheaper and more energy-efficient seems to be attractive to a large enough chunk of the market to have motivated Intel, AMD, and all their system partners to develop low-power chips and servers designed for high density compute and web/cloud environments. Up until now the debate was Intel versus AMD, and low power meant a CPU with four cores and a power dissipation of 35 – 65 Watts.

The Promised Land

The performance trajectory of processors that were formerly purely mobile device processors, notably the ARM Cortex, has suddenly introduced a new potential option into the collective industry mindset. But is this even a reasonable proposition, and if so, what does it take for it to become a reality?

Our first item of business is to figure out whether or not it even makes sense to think about these CPUs as server processors. My quick take is yes, with some caveats. The latest ARM offering is the Cortex A9, with vendors offering dual core products at up to 1.2 GHz currently (the architecture claims scalability to four cores and 2 GHz). It draws approximately 2W, much less than any single core x86 CPU, and a multi-core version should be able to execute any reasonable web workload. Coupled with the promise of embedded GPUs, the notion of a server that consumes much less power than even the lowest power x86 begins to look attractive. But…