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Comment by bsaul | Hacker News Reader

"By customizing nearly every inch of Google’s data centers and the hardware within them, including power supplies and cooling kits"

This is the second time i hear about a company building its own power supply, the first being apple for the apple 1.

As i know "nothing" about electricicty, i wonder : isn't power supply a solved issue at this point ? What could have they done differently that justify having its own production line for a power supply ?

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In the early days of Google, that would have been getting rid of the expensive, building- or cluster-wide UPS and adding batteries to the power supplies. Later, they switched to a rack-level UPS.

There isn't a lot to the Apple power-supply story. An Apple employee designed a switching power supply at a time when the industry was moving from linear to switching power supplies. Ken Shirriff writes more: https://www.righto.com/2012/02/apple-didnt-revolutionize-pow...

Yes, low-voltage power supplies are commodities. But they're also complex and critical to a product's operation (look up "glitching attacks" to see how squirrely power can influence behavior). If running hardware reliably at scale is part of your company's core competency, then your core competency will likely also include understanding the power being supplied to that hardware.

For datacenters, there are many design decisions for the power supplies and what voltages to use. The obvious solution is to use commodity PC hardware, so you have 120 volts AC to the computer's ATX power supply, which generates 12 volts DC, which is dropped to e.g. 1.5 volts on the motherboard to power the CPU. But this isn't the most efficient approach. You're going to get more efficiency with higher AC voltage (e.g. 208 volts). And you're going to get more efficiency with higher DC voltage (e.g. 48 volts). And also ATX power supplies aren't optimized for datacenters, since they have a lot of historical baggage and voltages that may not be needed (like standby). So there is a lot that can be done to squeeze more efficiency out of the power supplies.

Here's a Google presentation about changing to a 48V architecture: https://www.opencompute.org/files/External-2018-OCP-Summit-G...

Google has also used new circuitry for the DC-DC conversion. Here's a paper on their switched tank converter to drop 48 volts to 12 volts: https://storage.googleapis.com/pub-tools-public-publication-...

Have it hyperoptimised for your precise operating conditions?

Reliable, cheap, and available in high number power supplies are surprisingly hard to come by.

Delta makes tons of money on satisfying the "reliable, and available" points, but not the "cheap" one.

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