why cum ptf apply faster than predicted?

[bvining@xxxxxxxxxxxx]

The estimate is simply that, an estimate.  Factors that can influence
your time spent on the cum are the size/capacity of your system, how
many LPs you have installed, how many PTFs/Cums you may have previously
installed, etc.

The 4 to 8 hour estimate you saw was derived from testing in the lab
(using a very old and small system that actually took 9 hours to run
and was reduced to 4 to 8 to reflect what most users would likely see)
on a system that had every LP you can think of installed.  The letter
hopefully also indicated a 2 to 4 hour estimate if previous cums had
already been applied.

The 4 to 8 is hopefully a meaningful compromise to lead most users to
some appropriate estimate of their downtime.  To estimate from 1/2 hour
to 10 hours (or longer?) would most likely be such a wide range that
it would be worthless for most planning purposes (though you may feel
that the current estimate is about as worthy).

As others have mentioned, I would favor the over estimating rather than
under estimating of required time in this area.

Bruce

>
>Did a cummulative ptf load after a v4r4 install.
>
>The cummulative ptf's were on 3 cd's. The system is a very fast, non geared
>down 720.
>
>The cover letter said the ptf process would take from 4 to 8 hours.
>
>But it actually took 1 hour to load, apply and complete the auto ipl.  (
>17:57:31 to 18:47:50 )
>
>The history log msgs ( listed below ) show no indication of error.
>
>What does ibm base its time estimates on?
>
>This is not a trivial question.  Misstating the estimate results in much
>wasted time double and triple checking to make sure that nothing was missed,
>that the system is running ok.
>


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