RE: subject: iSeries Legends -- MIDRANGE-L

> Interesting.  I wonder if from the computer's point of view there is such
> a thing as a complex vs. a simple task?  IOW, does the computer know it is
> doing something complex vs. something simple?  I doubt it.

Yes it does.  It has to do with context switching.  Multitasking.  Event
driven processing.


> Whether it is
> dedicating substantial resources to something we perceive as simple or
> complex it is all just 1's and 0's to the computer.  So the complexity of
> the task makes no difference.

I disagree.


> What could make a difference is the different parts of the machine that
> are being exercized.  As you use more and more components you become more
> and more likely to trip over a bug.  The interesting conclusion of this
> statement is that a machine with fewer subsystems should be more stable.
> Therefore, if we believe that the iSeries has many subsystems all active
> all the time, we should also conclude that it is less stable.

This only works if the software is created equal.  It's not.  The error rate
on OS/400 systems is so much lower than that of other systems that you can
have literally dozens of OS/400 subsystems running together and still have a
lower error rate than the other boxes.

While I agree that multiple subsystems cause error rates to multiply, the
fact is that combining dozens of well-written subsystems will still create a
lower error rate than even a single poorly written one.  It is my contention
that the base subsystems of OS/400 are of that much higher quality that even
dozens of them combined are less error-prone than the few interacting
subsystems in any desktop OS.  This is the distinction of IBM-written OS
software, and is the central tenet of most of my arguments about quality and
TCO.


> I guess the statistic we are looking for is unit work done over uptime.
> That would be a really interesting research topic.

Very good!  I would like to see a $/RTpm figure (dollars per reliable
transaction per minute), which factored in both uptime and support costs.


> However, I think you misspoke when you said that your iSeries does complex
> tasks when it is idling.  That is a contradiction in terms.  If it is
> actively doing work then it isn't idle.

Have you ever written an operating system?  The only idle computer is one
that is powered down.  ANY machine is constantly handling at the very least
timer interrupts.  A machine as complex as the iSeries is doing everything
from checking hardware states to handling spurious TCP/IP interrupts.


> Furthermore, is it a good thing
> that the iSeries is contantly busy even when there are no user tasks to
> execute?  I think there is a strong argument that the answer is no.

Only for your toaster, James.  Real computers do work 24/7.

Joe