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From: PAT@rcgl1.eng.ohio-state.edu (Patrick Plaisted)
Newsgroups: comp.sys.mac.system
Subject: Re: Protected-mode snake oil
Message-ID: <5567@quanta.eng.ohio-state.edu>
Date: 16 Aug 90 00:02:01 GMT
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|  In article <1204.26c2fb48@waikato.ac.nz> ccc_ldo@waikato.ac.nz (Lawrence D'Oliveiro, Waikato University) writes:
|  >Frankly, I'm a little skeptical. As a regular user of both a Mac and
|  >a VAX/VMS cluster, I'd have to say that the relative frequency of
|  >crashes of the two systems, leaving aside the times I crash either
|  >one while debugging my own software, is something in the region of
|  >10:1. That is, it's not as much as 100:1.

From my experience of using both Macs and VAXen often, if your ratio is
only 10:1 then you have some serious setup problems with your VAX
cluster.  The VAX that I manage has crashed once in the last six months,
and that was due to using some public domain kernal mode code (you get
what you pay for :-) )

|
|  1) A VAX cluster has *lots* more hardware to go wrong than a MAC, so some of
|     those VMS crashes might be due to hardware trashing the system. Protected
|     operation will only catch a few of those, the rest may well result in
|     crashes.
|
|  2) A VAX cluster has *lots* more software to go wrong than a MAC. The kernel
|     itself is much larger and more complex. The kernel is very asynchronous
|     while the MAC OS is not.
|
|  3) A VAX cluster typically has *lots* more users than a MAC. This depends on
|     how it gets used, but hundreds of users isn't uncommon for a cluster.
|
|  Add all that up, and you would expect the VAX to be crashing a hundred or
|  a thousand times as much as the MAC. There really isn't *that* much to go
|  wrong with a MAC. They're pretty simple beasts. What's causing the VMS
|  system to be so reliable? Partly the fact that a lot of the code gets run
|  in non-kernel mode where errors don't take out the system in strange and
|  mysterious ways (or worse, simply change some kernel data).
|  [...]

All that you say is true, but a comparison between the two operating
systems is rather silly.  VMS consists of some 5.5 million lines of
code; Mac OS of a couple thousand.  VMS is designed to be a robust,
multi user operating system; Mac OS is for a personal computer.  For all
practical purposes, the only person that can crash a VAX should by your
system manager.  Anyone that knows a mac can crash it in about 30
seconds if they wish.  They are in two completly different worlds.

Not that I'm flaming Mac's (I really like them!), but the operating
system just isn't that robust.  Maybe when Mac's get real memory
management in 7.0 things will be better.  We can only hope...

	Pat

===========================================================================
Patrick Plaisted                     |pat@agvax2.ag.ohio-state.edu
System Programmer                    |  or if you want to
Ohio Cooperative Extension Service   |  torture me with unix:
The Ohio State University            |pat@klingon.eng.ohio-state.edu
2120 Fyffe Rd. Room #109             |
Columbus, Ohio 43210                 |     (614) 292-4338
===========================================================================
I'm not quite sure who's ideas these are;  I think they're mine...