Luke S Crawford wrote: > [email protected] writes: > >> I've seen top tier brand servers with redundant power supplies shut down >> because the power supply system inside the computer flaked out and decided >> that both power inputs were bad (disabling both power supplies) >> >> I've seen rats in the wall chew into power lines, shorting them out and >> downing the system. >> >> I've seen UPS systems that were reviewed by the maintinance company a week >> prior fail to handle a loss of power and shut everything down >> > > > The vast majority of data center power failures I have seen were do to > people, either through greed, ignorance, or inattention, overloading > a circuit. > > I've done it myself; once, when I was much younger and less experienced > than I am now. the thing most people don't realize is that not only > does power draw change based on load, it changes based on temperature, too. > > Of course, this is pure incompetence, but still, I'm sure, the #1 killer > of power in data centers. The problem is that most places charge per > circuit, so the business types want to use as much of each circuit as they > can. It seems like it would encourage more rational decisions if > power was metered. > > And those redundant power supplies. People get them, plug 'em into > different circuits, but then they load each circuit beyond 50%. One > of the circuits dies, and blam, of course the other one immediately > blows as well. It's not like they use half the power when one power > supply dies. > UPS maintenance time is also a common time for data centre-wide power outages. Like when an electrician drops a big, shiny, metal wrench across the bus bars. This has happened in *two* of our data centres over the last few years - by different electricians.
Failover-failure can also get you, when the failover circuitry and relays in a UPS fail to do their job. And I agree with Luke - very few data centres that I've seen have truly redundant power when you take into account the failover load. - Richard _______________________________________________ Discuss mailing list [email protected] http://lopsa.org/cgi-bin/mailman/listinfo/discuss This list provided by the League of Professional System Administrators http://lopsa.org/
