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Re: availability and resiliency

  • From: Valdis.Kletnieks
  • Date: Fri Sep 29 22:10:30 2000

On Fri, 29 Sep 2000 18:42:12 EDT, Andrew Brown said:
> an smp cpu configuration really going to help your uptime?  or
> are there operating systems or hardware out there that can say to
> themselves "hmph!  cpu 2 seems not to be working correctly...i'd
> better spin it down."

IBM mainframes have been doing this for decades.  I believe that both
OS/VS1 and VM/370 for the S370-158 supported this back in the 1973 timeframe.

About 10 years ago, our 3090-300 blew a TCM and lost one of the 3 CPUs.  As
I was sitting there diagnosing the problem at the console, I got a popup
dialog box from the onboard support processor.  Basically, it wanted to phone
IBM Hardware Support and tell them to send a guy with a new TCM, but it had
detected that it was more than 7 digits and therefor probably a long distance
phone call, was this OK?

Yes, it asked permission to rack up the phone bill before it called for
repairs itself.

Current mainframe state of the art is described in the IBM Journal of
Research and Development - Vol 43, Number 5/6 (Sep/No 99), which was
devoted to the G5 and G6 chipsets used in current IBM S/390 big iron.
The article "RAS strategy for IBM S/390 G5 and G6" (page 875) talks about
the system's ability to not only detect a failing CPU, but on detection
it will latch out the last known good state from the previous instruction,
and retry the failing machine instruction on a hot-spare.  That's after a
reset-and-retry on the failing processor has proven it's a hard failure and
not a soft one.

The mind boggles.... ;)

				Valdis Kletnieks
				Operating Systems Analyst
				Virginia Tech

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