As for AC power, I've walked into abandoned data centers with AC and UPS systems still in place, but every single rack-bottom UPS was blown -- all of them. In that case, not only do you have to buy new UPSes, you need to pay to dispose of the old ones.
Then there are the inevitable mysteries: A bundle of patch cables disappearing into a conduit, never to be seen again. Fiber links found coiled above a ceiling tile in the kitchen area. A 10-year-old Dell OptiPlex sitting on the floor in a corner running Windows XP with a sign taped to the screen saying "Do Not Touch" on an otherwise empty floor. That one turned out to be a "solution" to the fact that the departing company took its entire security system with it and left behind this little box to control physical entry. When it went down, the super had to be called to open every door.
Sorting through such relics has the feel of an archaeological dig, to the point where working in unfamiliar, abandoned locations can result in getting brained by a falling rock -- or maybe a ladder rack that someone disconnected and left sitting on top of a data rack. Such hazards are not to be taken lightly.
Remember that when you leave a site for the next company. Sure, the wiring will remain in place, but so will the inexplicable holes in the ceiling where you set up temporary cooling that one time. You're also not going to touch that morass of 10Base-2 coax that's been writhing around in the plenum for the past 20 years, waiting to be discovered by the next hapless IT guy.
But do your successors a favor. Write up a little ditty to explain a few details and give them a heads-up about the oddities you've learned to live with. If your supplemental cooling system occasionally turns the women's room into a sauna due to a blocked exhaust, they should probably know about it, don't you think?
This story, "Don't touch the skeletons in the server room," was originally published at InfoWorld.com. Read more of Paul Venezia's The Deep End blog at InfoWorld.com. For the latest business technology news, follow InfoWorld.com on Twitter.