Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!xylogics!world!bzs
From: bzs@world.std.com (Barry Shein)
Newsgroups: comp.arch
Subject: Re: Single user vs. shared (was Re: Killer Micros and vectorized code)
Message-ID: <1990Mar19.220617.26370@world.std.com>
Date: 19 Mar 90 22:06:17 GMT
References: <51771@lll-winken.LLNL.GOV> <100598@convex.convex.com> <52661@lll-winken.LLNL.GOV> <1990Mar18.023523.4034@ultra.com> <52817@lll-winken.LLNL.GOV>
Organization: The World @ Software Tool & Die
Lines: 52
In-Reply-To: brooks@maddog.llnl.gov's message of 18 Mar 90 19:50:16 GMT


The argument is that because a personal computer/wkstn is idle 99% of
the time therefore it would be better shared.

The problem is that although this argument seems great in theory, in
practice it tends to have real problems.

When people share a computer things go wrong, the biggest thing that
goes wrong is that one cannot estimate, day to day, what to expect
from the shared computer.

One day it can look up 1000 queries in an hour, the next day you only
get 10 per hour (oops, someone out there is running a CPU hog.)

One day you have lots of disk space, the next day you can't save the
file you just edited AND YOU HAVE NO CONTROL over the situation (oh,
you might have political control, but instead of just cleaning up a
few files you now have to have a Computing Resources committee
meeting.)

One day someone "out there" tickles a bug that keeps crashing the damn
thing...shouldn't happen...that and 50c *might* get you a cuppa (hey,
ya know what happens, no one even *knows* for the first week who's
crashing the thing, certainly not the guilty party, it just keeps
going down.)

And we won't talk about the Animal Farm nature of shared computers,
all pigs are equal, some pigs are, however, more equal.

	Control and predictability, real important.

Ever share a bathroom with a few people? Works in theory, hey, no one
uses the bathroom more than 30 minutes/day so sharing among 10 people
should be fine! Uh-huh. Ever share one bathroom among four or five
people? Don't work too well...

Computers are similar, sure, they're idle 99% of the time, except
never when you need them (like from 3-5PM, typically.)

Why do you think so many frantic hackers became night-owls?

Anyhow, a simple resource sharing argument is just that,
oversimplified. There certainly are resources that can be shared, but
it takes more thought to make it work right than is being presented.
Most sites can hardly put up with sharing a printer among several
people (a printer that's idle 90% of the time, I may add, but never
when you need it.)
-- 
        -Barry Shein

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