Facebook announces next-generation Open Rack frame

Re:Facebook announces next-generation Open Rack frame by walrus01 on Saturday March 16, 2019 @08:22PM (#19411337)

DC power wise, the original reason why they did this is that it's grossly inefficient to have a 42RU worth of 1U servers, each with its own individual 110-240VAC to 12/5VDC power supply in it.

Or the equivalent of that with four-servers-in-2RU type setups, but also with AC to DC power supplies.

They centralized the AC to DC conversion in a single unit in the rack, feeding either 277VAC or 480VAC to each rack, and ran 12VDC to each server. The new system wisely moves from 12VDC to 48VDC (same as most telecom equipment), and probably has basic DC-DC converters in each server unit for 48 to 12VDC conversion.

They've also gone with custom motherboards that entirely eliminate the 5VDC rails which are distributed by 'normal' ATX server power supplies.

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Re:Facebook announces next-generation Open Rack frame by baybal2 on Saturday March 16, 2019 @09:25PM (#19411576)

There are 90%+ efficient reasonably cheap flex psus, but the mainstream is around 80%.

So, you would not be saving much if you only have access to 110 or 220 mains.

The economy changes though if you can get access to industrial 3 phase linkup at 400V, and can avoid additional low step down transformers.

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Re:Facebook announces next-generation Open Rack frame by vanderZwan on Sunday March 17, 2019 @06:32AM (#19413306)

> So, you would not be saving much if you only have access to 110 or 220 mains.

"Much" is a relative term here, no? Like, doesn't that kind of depend at the scale at which Facebook operates?

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Re:Facebook announces next-generation Open Rack frame by detaro on Sunday March 17, 2019 @06:37AM (#19413323)

I read somewhere that part of it was also doing the short-term battery backup on a rack-level, without needing conversion back to mains AC and then again back to DC in the server for it.

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Re:Facebook announces next-generation Open Rack frame by bigbangchina on Sunday March 17, 2019 @06:53AM (#19413358)

You can use microwave oven transformer to step to 1000VDC then simply use step down converter in each rack.

I am doing this for my home lab with 100 servers.

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Re:Facebook announces next-generation Open Rack frame by altmind on Monday March 18, 2019 @01:51AM (#19418954)

Hmm, but arent there low-voltage DC server PSU? I know that a lot of network gear(cisco) can be powered by 48V DC. Quick googling shows there are a lot of options like these. I dont see how designing own server form factor is a better solution than using COTS components.

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