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Re: Understanding iSeries Performance Positioning



fixed

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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