Not content with dominating the world of smartphones and tablets, makers of low-power ARM chips are setting their sights on the server market. While x86 servers are still the norm, there have been hints for some time that ARM might become a presence in the data center. Another small, early step toward an ARM future was taken this week as the makers of an infrastructure-as-a-service testbed added ARM servers as a free option for developers.

The free cloud service is called TryStack. It works a lot like Amazon's Elastic Compute Cloud, except that it runs on the open source OpenStack software, and is intended as a sandbox, not to run production code. Although OpenStack supports ARM, TryStack was initially set up to run just x86 servers, and is powered by 156 cores, 1,040GB memory, and 59.1TB of disk storage. What's being added now is free access to HP's Calxeda-based Redstone servers running Ubuntu Linux, ARM chipmaking startup Calxeda announced today.

In addition to HP and Calxeda, the hardware, software, and hosting is being provided by OpenStack, Canonical, Core NAP, and Rackspace. The servers use Linux containers, or LXC, a form of virtualization that improves server efficiency but allows only one operating system instance per processor core (akin to Solaris containers and FreeBSD "jails"). The shared, virtualized nature of the resources makes TryStack unsuitable for benchmarking and power measurements, but dedicated hardware access is planned for the end of this year.

ARM has limitations compared to x86—32-bit is still the standard in the ARM world, for example. But there are benefits too.

"What user experience can you expect? Well, most people will find it a bit boring; it looks and acts just like any Linux server instance," Calxeda wrote. "But that’s exactly the point. For most code, it’s just compile and go. Or for interpretive workloads like Java, PHP, LAMP stack, and node.js, it's just load and go. Just a little slower and much less power. Each quad-core server consumes only five watts under load and 1/2 watt at idle."

To try it out, developers should make a request to join the TryStack group on Facebook, and then request access to the ARM server zone. Calxeda said it's hoping to make the sign-up process a bit easier soon. But, hey, it's free, so who's complaining?