In 2011, HP and Calxeda formed a partnership for ARM-based servers for datacenters. The idea was to make servers out of tens or hundreds of small ARM processors that can handle simple data transactions (such as web requests), that can scale well and that use little power.
It was a good idea, except for one problem: ARM chips weren't ready for servers at that time. Calxeda, a startup striving to design ARM chips for servers, built its first server chips around the 32-bit Cortex A9 CPU. Unfortunately for the small company, 32-bit chips don't work very well in datacenters, and Cortex A9 wasn't powerful enough to handle server tasks, either.
Calxeda also had some delays. By the time the company came out with its first server chip, the Cortex A9-based EnergyCore ECX-1000, the next-generation Cortex A15 CPU supporting up to 40-bits of memory was already out. A newer 28nm process was developed, making Calxeda's 40nm chip obsolete in terms of performance/power. Finally, HP decided to forget about Calxeda, make its chips architecture-agnostic, and just use Intel Atom chips for its Moonshot servers. Several months later, Calxeda announced bankruptcy.
HP doesn't seem to have forgotten its original vision about focusing on low-power/high density ARM chips for datacenter servers. It recently partnered with Applied Micro, the first company to ship an ARM chip that is finally ready for servers, thanks to its 64-bit ARMv8 ISA and its custom core optimized for server use.
Today, HP announced the new Proliant m400 server using Applied Micro's X-Gene chip which comes with eight 2.4 GHz custom ARMv8 cores. A single m400 has 45 of these X-Gene cartridges, and each cartridge supports up to 64 GB DDR3 RAM and 480 GB flash storage and runs Ubuntu server 14.04 LTS.
Applied Micro isn't the only company making ARM server chips for HP's Moonshot servers. Texas Instruments and AMD are also working on it. AMD will ship its Cortex A57-based server chip later this year, while TI is shipping a Cortex A15-based server chip right now. However, the TI server chip doesn't support the latest ARMv8 ISA, making it suboptimal for enterprise use. HP only supports Ubuntu for these systems, but the company is "interested in working with Red Hat" and other Linux suppliers as well.
Applied Micro and AMD may be shipping the first real ARMv8 chips for servers this year, but it's still early for ARM chips in the server market. As Cavium and Broadcom join them next year, and Applied Micro releases a new generation X-Gene chip, the competition should heat up. With several big players already in the market, their products should quickly improve, which could then raise the interest of more enterprise customers for efficient ARM-based server chips.