[lclarkmichalek]

What you saw likely wasn't a UPS, but an RPP

> A data center typically spans four rooms, called suites, where racks of servers are arranged in rows. Up to four MSBs provide power to each suite. In turn, each MSB supplies up to four 1.25 MW Switch Boards (SBs). From each SB, power is fed to the 190 KW Reactive Power Panels (RPPs) stationed at the end of each row of racks.

https://research.fb.com/wp-content/uploads/2016/11/dynamo_fa...

The UPS role is taken more by BBUs (Battery Backup Units). https://www.youtube.com/watch?v=KNsposM0sJE has lots of info about them.

(I work for FB, on entirely unrelated things)

[LinuxBender]

They specifically called em out as UPS and talked about the efficiency improvements over having a dedicated UPS room. I don't remember the percentage numbers though. It was orders of magnitude less power loss. It could be they ditched all of that hardware by now. This was some time ago. You might ask some of the old timers in the DC. They probably have pictures of the hardware.