[ On Friday, April 6, 2001 at 22:11:36 (+0200), wojtek@wojtek.3miasto.net wrote: ]
> Subject: Re: what i see ;) port-s390
>
> this isn't more useful than for testing IMHO. 

that's just the tip of the iceberg!
 
> why run 2 unix tasks while you can run one unix and needed amount of
> processes under it

because now you can run zillions of independent virtual *systems*, all
on the same big pile of hardware.  It becomes enormously cost-effective
when you ramp the numbers up a bit....

Think about scenarios like web server farms for private hosting -- you
give the customer the root password and let him play all he wants!

SourceForge could run every project on a separate virtual system and
have less than half the security worries.

Even if you only have a few big "projects" (eg. a database, maybe a
manufacturing system, accounting, etc.) can all be partitioned nicely
and in ways that improve their security.  Resource management is much
easier to do when you can adjust how VM allocates physical resources to
each partitioned virtual system.

The first time I saw an Amdahl UTS system do a "make" in src/bin/csh
(which was at the time the biggest program native on the system) I was
very impressed, especially since I'd seen about a hundred active users
were busy working away at the same time.  When I was subsequently told
that this was in just one of sixteen virtual systems, with about three
thousand active users total on the hardware at the time, I was totally
blown away.

Of course my Intel PII-300mhz machine can do a build of the same source
code in even less time with a compiler that's probably at least an order
of magnitude larger and more complex.  With some of the new Intel server
boards with multiple CPUs and multiple independent PCI buses, it might
soon be possible to achieve similar throughput on what amounts to not
much more than a desktop machine.  Mind you the really big DEC Alpha
machines should be capable of similar thorughput, and of course a Sun
E10000 is quite a monster too.

However without an underlying "hardware management system" like IBM's VM
operating system on which to host logical virtual systems, it's almost
impossible to manage such powerful hardware effectively for any truly
general purpose multi-user computing environment.

-- 
							Greg A. Woods

+1 416 218-0098      VE3TCP      <gwoods@acm.org>     <woods@robohack.ca>
Planix, Inc. <woods@planix.com>;   Secrets of the Weird <woods@weird.com>