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more on United computer outage
From: David Farber <dave () farber net>
Date: Thu, 5 Jan 2006 16:37:03 -0500
Hell we did better in the 50s with ESS Telephone systems Begin forwarded message: From: John Levine <johnl () iecc com> Date: January 5, 2006 4:21:57 PM EST To: dave () farber net Subject: Re: [IP] more on United computer outage
A "processor" failure??!! djf
Yup, almost certainly processor as in CPU. Airline systems like Galileo still run on tight clusters of IBM mainframes. These are basically database engines with phenomenal transaction rates. While it's not hard to do distributed searches in parallel, updates are limited by locking, which works worse the more computers you have contending for the locks. So the core systems are clusters of a few mainframes, each with a couple of dozen CPUs and shared memory, cranking away on the transactions. Modern mainframes are designed to be very, very reliable. The CPUs come in groups of maybe 16, with at least two of the 16 reserved as spares, and extensive hardware checking so that if a CPU fails, one of the spares takes over immediately. They have facilities for doing hot add and remove of equipment which work well enough that the system uptime is measured in years. It sounds to me like one of the CPUs wedged in some way that the recovery hardware couldn't deal with, and if the system is wedged, it's down. This is a big embarassment for IBM since the main selling point for million dollar mainframes is reliability. I'll be interested to hear what if any reports we get about what the problem was. R's, John ------------------------------------- You are subscribed as lists-ip () insecure org To manage your subscription, go to http://v2.listbox.com/member/?listname=ip Archives at: http://www.interesting-people.org/archives/interesting-people/
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