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

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_facebook_s_data_center-wide_power_management_system.pdf 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 https://www.youtube.com/watch?v=KNsposM0sJE has lots of info about them. (I work for FB, on entirely unrelated things)