Re: cpw. unconstrained vs constrained.

[Philipp Rusch <Philipp.Rusch@xxxxxxxxxxxx>]

Hello Steve,
with that particular model 170 system the restriction is easily explained:
that 2176 processor would need far more disk arms than the maximum
possible (10 disks) on a 170 with expansion tower to run at it's full potential.

Somewhere in the IBM AS/400 Web jungle there is a good explanation
of number disk arms vs. performance on different AS/400 models.
I don't have the URL at hand at the moment, sorry  ...

I often explain to customers the close relation of throughput of the disk
subsystem and CPU power of an AS/400 with an example of the mentioned
article:
Having a 620 with about 800 CPW running "heavy mixed load" benchmark
(means a mix of batch and interactive tasks) that particular model would
need a 117 disk arms (!!) at least to run at full potential processor speed.

Adding more arms to an AS/400 often gives more effect than most people
would believe (despite adding lots memory, of course).

HTH, Philipp Rusch

Steve Richter schrieb:

> first a quick ebay report ....
>
> ibm is more and more the best source for systems auctioned on ebay.
> currently about 5 systems on auction. by far the best price compared to the
> saps who put up systems for over $10k and never get a bid.
>
> here is a good example:
>
> http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=2017727020
>
> it is a 170/2176.  constrained cpw 125/40.  unconstrained 319/40.
>

As you notice, the available interactive part of CPW remains the same in both
environments, as 40 CPW is well under the max of the machine, but that "RAW"
potential power of the CPU itself is much higher than you could achieve in the
model 170 box.

>
> What is the difference between constained and unconstrained cpw.    Will a
> batch job that is mostly cpu and memory bound, little io, run unconstrained
> ?
>
> Thanks,
>
> Steve Richter
>