We've just released the v1.0 Open Rack specification. The new specification documents the evolution of the Open Rack over the last few months since the 0.5 version was published:
• Exclusive focus on a single column rack design.
• Higher inlet temperature of 35°C, which reflects other Open Compute designs and real-world data center temperatures.
• Network switches that can be deployed in various configurations, not just above the topmost power zone.
• Compute chassis are 1xOpenU - 10xOpenU high, and are supported on L-shaped brackets that directly snap into the vertical structural rack posts. These brackets, installable without tools, can be mounted at 0.5xOpenU (24mm) increments.
• Maximum height is dictated by the size of the power zone, but heights above the suggested maximum of 2100mm should be given closer scrutiny for stability.
• Innovative clips easily mate the chassis power connectors to the bus bars.
The Open Rack is the first rack design to diverge from the existing 19" rack standard, which had its origins in the railroad industry and was later adopted by the recording industry, among others. The 537mm width (about 21 inches) of the chassis has a lot of practical engineering benefits, like improved airflow, greater energy efficiency, and better volumetric efficiency, as there is more space used for IT equipment instead of just air and metal.
The rack itself is 600mm wide, which makes it the same as the overall width of a 19" rack, so it fits into existing data centers worldwide.
The Open Rack: A Hardware API
The Open Rack is more than just a server cabinet; it's also an abstraction layer between the server and the rack, like a hardware API. The rack's modular equipment bay — which contains the compute, storage, and other related hardware — provides a large degree of flexibility when it comes to configuration. The Open Rack design guide provides specifications and guidelines to show suppliers of IT equipment how they can build systems compatible with the Open Rack.
There is also a lot of versatility when it comes to powering the rack. Depending upon the configuration, the rack can draw power from one to three pairs of bus bars, which in turn provide power to the power shelves in each rack. Using Open Compute Project power supplies, the power shelf is 95% efficient. In the event of AC power loss, the power shelves can draw DC power from either the OCP battery backup cabinet or high-density lithium-ion battery packs.
Finally, the Open Rack is also simpler to maintain. It's tool free, so servicing is faster and easier. The movable shelving within the rack and the lack of rail kits lets you deploy all sorts of configurations.
Next Steps
So what's next? Facebook has deployed this version of Open Rack for testing in its data centers, and we're eager to hear your feedback on the specification. After receiving and reviewing your comments over the next couple of weeks, we'll set up a conference call for everyone to share feedback. In the meantime, download the spec, the rack and PDU mechanical files, and the design guide.