From: martelr@WTFD.ORST.EDU (The Iron Monk)
Newsgroups: comp.unix.misc
Subject: Re: How many users will bog down UNIX on a PC?
Date: 13 Apr 92 21:41:55 GMT
Distribution: na
Organization: Weatherford Hall, Oregon State U.

In article <1971@wrdis01.af.mil> jshumate@wrdis01.af.mil (Shumate Jason) writes:
>My office has a project coming up and we have several alternatives to 
>choose from.  We have 3 CD-ROM discs that we need to make available to
>several people.  One suggestion was to buy a 486 PC and run either SCO UNIX
>with Open Desktop so we can run DOS under it to access the CD-ROMs or
>buy Interactive's UNIX and use VP/IX to run DOS to access the CD-ROMs.
>Let's assume for the sake of argument that we will buy some kind of CD
>jukebox that we can use with the application.  Suppose also that all of
>our users on the PC will only be running character-based applications, not
>graphics-based such as X-Windows.  If we had 16 simultaneous users on the
>PC, all running either Open Desktop or VP/IX so they can use DOS to get to
>the CD-ROMs, what kind of response would we get?  Would response time be
>really bad, tolerable or what?  I would suppose for sake of argument that
>the 486 PC we would get would run at either 33 MHz or 50 MHz.  Any personal
>experiences with running DOS under UNIX on a PC, even if it is on a 386,
>would be very helpful.  We can't get anyone to tell us how many users would
>cause a PC to start slowing down appreciably, and we really need some kind
>of information to gauge whether this is a practical solution to the problem
>or not.  Again, any personal experiences relating to this topic would be
>greatly appreciated.

Hello.  I'm a sysadmin for kallisti.wtfd.orst.edu.  Kallisti is a 486/33 PC
that we run to provide services for our dorm.  (We run MACH, by the way.)  One
thing I can tell you is that we get excellent performance--our little PC runs
faster than any other machine on campus--most of the other machines are so
loaded down that they can't help it! :-)  But we fit 16 to 17 people on it with
no appreciable lag except when someone is compiling or running X.  The biggest
problem with a PC is that you tend to run out of memory very quickly.  The
processor handles most things with ease, especially if you'll be doing a 
textual interface--five to six people running rn, a couple running emacs,
and a few others doing their own things really don't slow kallisti down that
much.  But when you get too many processes going and it starts to disk swap,
then you really notice!  If you want to run UNIX on a PC, and I think it's a
very feasible option, you should make sure that you put as many simms in the
thing as you can!  Memory, memory, and more memory--in our experience, the
processor runs very quickly, but the lack of memory REALLY bogs down the 
system when you get >15 people on running big processes.  VP/IX would be such
a huge memory load, and I would suggest looking into exactly how much memory
you'll need to have before (read *BEFORE*) you buy anything--if you need 2 meg
per user running VP/IX, (made up figure--I've had no experience with VP/IX--we
keep DOS on a seperate partition), you'd better be really sure that you can get
32 meg in that sucker.  The more memory you have, the faster your system goes
(to a point, of course) because you don't need to swap to disk as much.  I'd
go so far as to suggest getting 64 MB of memory (if possible) and working with
that--double what you'll need.  (It will actually be double what you think 
you'll need--things NEVER work out right...)  That's just my two cents--I'm 
not a techie, and I don't pretend to know more than I do.  I think you can
do it, from what I know of VP/IX and UNIX and PC's, but that's just what I 
know and I could be misinformed.  My experience with this type of thing tells
me that you want memory and you want a 486/50, but other than that you 
shouldn't have any huge problems.  Keep us posted!

Just another student!

Raph
--
martelr@kallisti.wtfd.orst.edu
Newsgroups: comp.unix.misc,comp.unix.sysv386