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Microsoft's Plans for Windows Server on ARM

• By Kurt Mackie
• 03/09/2017

Microsoft shed some light on how datacenters will operate with Windows Server on ARM processors.

It turns out that Microsoft is currently running Windows Server on ARM machines in its datacenters using chips from multiple vendors, including Cavium and Qualcomm. The effort is apparently at the testing level right now. However, Leendert van Doorn, a Microsoft Distinguished Engineer, stated that Microsoft already has "future deployment plans on ARM servers" aimed for its datacenter infrastructure, in an announcement today. Moreover, Microsoft is working with ARM Limited, the provider of the chip designs, on open standards for ARM64 servers for use in datacenters.

The Windows Server on ARM announcement is one of a few Microsoft announcements timed for the 2017 Open Compute Project U.S. Summit happening this week, where Microsoft is a sponsor, along with Intel and Facebook. The OCP was originally started by Facebook engineers to share datacenter knowledge, but it has since become an organization that fosters open specifications for datacenter hardware and software. Microsoft joined the OCP in January of 2014, contributing multiple specs since that time.

The prospect of running Windows Server on ARM infrastructure in datacenters was just speculative talk about six years ago. However, it had always been clear that Microsoft was at least toying with the idea. Now, the announcement by van Doorn suggests it's here to stay.

ARM chips have some benefits for datacenters, including "high Instruction Per Cycle (IPC) counts, high core and thread counts," as well as "connectivity options," Doorn explained. Microsoft is also looking to flip the old paradigm of having to build software for specific hardware with ARM chips.

"Due to the scale required for certain cloud services, i.e. the number of machines allocated to them, it becomes more economically feasible to optimize the hardware to the workload instead of the other way around, even if that means changing the Instruction Set Architecture (ISA)," Doorn explained. He added that ARM chip designs are "much more amenable" to handling future new ISA enhancements "without disrupting their installed software base."

Microsoft sees ARM chips as helpful for its internal datacenter services, handling workloads such as "search and indexing, storage, databases, big data and machine learning," according to Doorn.

Other favorable conditions for ARM developments include "a healthy ecosystem" of ARM server vendors that can advance technical capabilities. In addition, the proliferation of ARM chips in the mobile world has brought together "an established developer and software ecosystem for ARM," Doorn explained.

Microsoft and its partners are showing off Windows Server on ARM at the OCP U.S. Summit this week. One demo uses Cavium's "64-bit ThunderX2 ARMv8-A server processor SoCs for datacenter" running on Inventec server hardware. The other demo features Qualcomm's "Centriq 2400 ARM server processor."

Cavium and Qualcomm have both produced motherboards that conform to Microsoft's Project Olympus specs. Project Olympus is a Microsoft-initiated effort at the OCP that aims to accelerate datacenter innovations through the early sharing of open source hyperscale cloud hardware designs. Conformance with Project Olympus specs means that servers using those motherboards can be "seamlessly" deployed in Microsoft's datacenters," Doorn explained.