Re: Tips for user ASP

>From: "Al Barsa" <barsa@barsaconsulting.com>
>
>2).   Just give them their own library names in the system ASP, and your
>company get's the benefit of more disk arms.  With the system moving from
>proprietary DASD to PC commodity DASD, DASD densities will grow through the
>roof, and I predict that the next bottleneck for many ships will be DASD
>arm contention.
>

I agree Al.  In fact I think the next performance bottleneck _has been_ DASD
arm contention for several years now.  Larry Bolhuis and I have beat our
drums, and beat our drums, and beat our drums, but everyone has said: no,
no, no, probably not a problem, because of faster disks, faster disk
controllers, and write cache, and more write cache, and you should believe
in the new technology...

And we said: it _is_ a problem.  and it is getting worse...  (I have heard
that it is hard to buy 4 gigabyte disks these days.) There are a lot of
systems out there right now that are seriously underperforming.  The reason
they are not performing well is because they don't have enough disk arms to
bring the stuff they need into memory.  The CPU is sitting idle a lot of the
time waiting for data to come in from disk.  or worse yet the processor is
spending a lot of cycles deciding what to throw out of memory (which
requires more disk accesses) so it can start processing something else,
because the thing it was working on a blink ago is still (and forever)
waiting for something to come in from disk.

And although it sounds pretty simple and you would think that you would know
when it was a problem, it is not simple and it is pretty dog-gone hard to
figure out what is actually happening when it is happening to you.

And another thing...  I think this a problem that we will all have with
computers too, not just ships.

--  Charly



"Nothing would please me more than being able to hire ten programmers and
deluge the hobby market with good software."  -  Bill Gates in 1976

"We are still waiting..."  -  Alan Cox in 2002

"Linux is only free if your time is worthless."


Charly Jones
253 265-6244
Gig Harbor
Washington USA



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