Re: Understanding iSeries Performance Positioning

["Alexei Pytel" <pytel@xxxxxxxxxx>]

> IBM states (AFAIRC) somewhere that the CPW is calculated on the "maxed"
out
> configuration. This is hard to believe: do they really mean (for their
biggest box)
> that CPW is determined for a box with 128GB RAM and 19TB DASD?

Believe it.
Not every configuration is measured, of course - too expensive. Some are
extrapolated.
If you will look at official CPW tables, those which were calculated (not
measured) are explicitly marked so.
The largest configuration is, however, measured.

> With most other platforms the various
> benchmarks (as you point out) are more or less public, so some validation
> of the numbers is possible. The CPW is much harder to get a handle on.
I am curious how can you validate, say TPC-C benchmark for maxed out Sun
Enterprise configuration - cost of such benchmarks is easily in millions.

I also want to say, that normally vendors are not interested in
benchmarking small comfigurations. For example, you can find TPC-C figures
for large Compaq servers, but do you know what is the TPC-C rating of a
Compaq box you buy in a shop on a corner ?

Besides, CPW was never intended for comparison with oter platforms. For
this, IBM publishes lots of public benchmarks (TPC family, different kinds
of ERP, Java, Lotus etc. etc).
CPW was meant only to differentiate boxes in the same family, so I guess in
a *legal* sense, CPW numbers are a kind of arbitrary.


Alexei Pytel - speaking only for myself


                    "Leif Svalgaard"
                    <leif@leif.org>           To:     <midrange-l@midrange.com>
                    Sent by:                  cc:
                    midrange-l-admin@mi       Subject:     Re: Understanding 
iSeries Performance
                    drange.com                 Positioning


                    09/07/2001 12:10 PM
                    Please respond to
                    midrange-l





From: Nathan M. Andelin <nandelin@relational-data.com>
> I'd like to gain a better understanding of the benchmarks that IBM uses
to
> calculate the relative CPW ratings of their boxes.

I think you'll have an uphill battle here. IBM states (AFAIRC) somewhere
that the CPW is calculated on the "maxed" out configuration. This is
hard to believe: do they really mean (for their biggest box) that CPW is
determined for a box with 128GB RAM and 19TB DASD?
Since boxes may differ wildly in terms of (say) number of disk arms,
it seems hard to compare just based on processor/feature codes.
Our f(r)iend CFINT never seems to soak up I/O, so how can "the
knee of the curve" be meaningfully defined? Remember that CFINT
will begin to kick in after the knee, but I never see it soak up anything
but
CPU cycles.
Seems to me that there is some voodoo going on. Some rather arbitrary
numbers being floated around. With most other platforms the various
benchmarks (as you point out) are more or less public, so some validation
of the numbers is possible. The CPW is much harder to get a handle on.



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