On 08/18/2014 08:04 AM, Nims,Alva John (Al) wrote: > Oh, you reminded me of the "Big Red Button" or "Big Red Pull" which was NOT a > POR, it was for a few systems a Power Off with NO chance of a Power On > anytime soon, because a CE would have to come in and replace the circuit that > a knife just sliced through to do the Emergency Power Off that the "Big Red > Button" just forced through. > > Al Nims > Systems Admin/Programmer 3 > Information Technology > University of Florida > (352) 273-1298 > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On > Behalf Of Phil Smith > Sent: Friday, August 15, 2014 6:05 PM > To: [email protected] > Subject: Re: Mainframe jargon and acronyms wasRe: AMBLIST, AMASPZAP, and UNIX > Program Objects > > Let's not forget "Poughkeepsie reset" and "BRS" (Big Red Switch), both > meaning a POR! > > > >
The Emergency Power Off switch interlock on all IBM processor models that we had over a period of several decades was only a mechanical interlock on the EPO switch itself -- at least so on all our processors where it was accidentally or out of ignorance used (it was never deliberately used). Although it cuts all processor power immediately and does not allow for normal power-down sequencing or delayed shutdown of processor cooling, I can't recall a case where damage was done by use of the processor EPO, although the IBM CE was always called in to check out the system afterwards. At least on some processor model (360/65?) , the beginning of the diagnostic procedure was to just reset the mechanical trip in the switch to reset the EPO switch, do a power-up and see if everything worked. My recollection is that after one EPO incident our in-house IBM CE did something to disable the EPO mechanical lockout on the processor EPO switch, so if the EPO were tripped when the CE was off-site and SysProgs got in before the CE he could advise them to reset it and try to power-up while he was in route. Somewhere along the line people seemed to realize that use of the processor EPO was actually a cleaner way to shut down the system than a power failure (utility power failure without a UPS or a UPS failure), as power failures can involve spikes and other abnormal voltages on one or more power phases as the failure is occurring. Our normal recovery procedure from a power failure at least from the 1980's on was to call in System Support staff and the IBM CE (in case he was needed), wait for stable power to be restored, then start power-up of all devices and see if anything failed to come back up, then advise the CE what units had failures. We occasionally had some devices that wouldn't power up, but it was usually DASD or some other I/O equipment and not the processor itself. It never made sense to treat use of the processor EPO as a more serious event than a power failure and force a CE to be on-site to start recovery from the EPO when that was not the case for a power failure. -- Joel C. Ewing, Bentonville, AR [email protected] ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
