Memes

Most of their staff probably is security. The stuff in racks and cages is customer owned.

If I had to guess, from what I've seen in a data center, there's only a handful of "smarthands" on site. Maybe a NOC staffed by a handful of people. A wire tech /LV electrician or two to handle cross-connects. A regular sparky or two for runs to new cages (these are build to spec, i.e. for each cage you're putting in, you probably want at least 2x 220v 30A runs. If you got dense power-hungry compute or a JBOD...that's even more.

Oh yeah, a few HVAC people...depending on how cooling is done. Some places just have a raised floor that gets blast full of cold air, with vents on the cold aisles, and returns on the hot aisles. Some places use in-rows that need refrigerant pipes through. I imagine the latter would need more HVAC staff for maintenance/builds than the former.

1-2 for shipping/receiving, 1-2 janitorial.

I dont know for sure but I'd wager the tradesmen and IT folk are on-staff, not contracted. They always have something to do.

But I still wouldn't be surprised if you told me that a datacenters biggest department (by payroll dollars) was security.

The beauty of datacenters (one of, at least) is the customer being able to put that all on one bill. They charge per square foot for cages, but they also charge by amp available. So a 50A 220v will cost significantly more than a 30A, even if you only draw 12A. And then they charge per-use fees on things like cross-connects (inter-cage or cage to meetme room) or smarthands.

Everything else is rolled in. You don't have to worry about maintaining all your own elec, or cooling. Water leaks? Overheating? Someone else's problem. Redundant A/B power with generators, UPS, and ATS, giving five-9s per side? Got it covered.