Open Compute Hardware Adapted For Colo Centers

1sockchuck writes "Facebook has now adapted its Open Compute servers to work in leased data center space a step that could make the highly-efficient 'open hardware' designs accessible to a broader range of users. The Open Compute Project was launched last year to bring standards and repeatable designs to IT infrastructure, and has been gaining traction as more hardware vendors join the effort. Facebook's move to open its designs has been a welcome departure from the historic secrecy surrounding data center design and operations. But energy-saving customizations that work in Facebook's data centers present challenges in multi-tenant facilities. To make it work, Facebook hacked a rack and gave up some energy savings by using standard 208V power."

Re:208v? ha!

[Anonymous Coward]

The equipment was originally designed to run at 277V (1 leg of a 3-phase 480V system), but is instead running at 208V (3-phase system where each leg is 120V). So while 208V may be higher than most US equipment, it's still lower than what they typically use.

dom

Re:208v? ha!

[tlhIngan]

You lose efficiency, thus wasting energy, when you convert the 208v AC into the low DC voltages necessary to run the computer. Instead of each computer having a power supply that converts from high AC to low DC some companies are using large AC to DC power supplies to power whole racks of servers. These servers run on DC.

Low voltage DC is piss-poor for distribution because power losses in wires increases at the SQUARE of the current. 120V@1A will have far lower losses than 12V@10A - 100 times less.

The big AC to DC places use high-voltage DC for that reason - lower current cables are far easier to handle than high current cables (the thickness of a conductor depends on its current - ampacity. The insulator does have to get thicker for higher voltages, but it's a lot more flexible than a thick 00-gauge wire.

DC-DC converters are fairly efficient and converting down to where you need has less losses than trying to shove 100A of 12VDC to a rack (assuming said rack only consumes 1200W. I think a modern rack can easily draw 3600/4800W fully loaded with servers which would mean up to 400A at 12V to the rack - calling for seriously thick cabling).

Oh, and what happens when you have high currents flowing at low voltages? You get welding. Because IIR heating is far more effective when you're passing huge currents through.