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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical RE: "They all suck!" Re: UPS failure modes (was: fire at NAC)
One thing people seam to have forgotten is that with added redundancy comes added complexity that is many cases out ways the gain. Shaun > -----Original Message----- > From: Alex Rubenstein [mailto:[email protected]] > Sent: Thursday, May 29, 2003 1:40 PM > To: Sean Donelan > Cc: [email protected] > Subject: Re: "They all suck!" Re: UPS failure modes (was: fire at NAC) > > > > > > UPSes (and UPS batteries) do fail, sometimes in catastrophic ways. I > > would not design any critical system on the assumption that any > particular > > component won't fail. High availability is about designing for failure. > > Sometimes there is a long time between failures, other times they occur > > early and often. The most annoying thing about UPSes is they fail at > > exactly the time they are needed most. > > Except, that: > > Even in instances where 'High availability' is designed, in the case where > one of the units has a failure that causes a fire and FM200 dump, either > the FM200 will still trigger an EPO, or the fire department will. > > So, the second 'high available' unit will generally not prevent you from > dropping the critical load, but instead, will help you get back on line > quicker. > > A much cheaper and easier to implement external maintenance > make-before-break bypass will accomplish the same thing. > > I've heard many a story of the paralleling gear causing the problem in the > first place, as well... > > > > -- Alex Rubenstein, AR97, K2AHR, [email protected], latency, Al Reuben -- > -- Net Access Corporation, 800-NET-ME-36, http://www.nac.net --
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