Re: iSeries Disk Pricing

While the number of arms is of course, very important, the cache in the DASD 
and the
speed with which the DASD can transfer data has a perhaps, unexpectedly large 
impact
on overall performance.

You *might* find that you only need 1/2 the number of arms to get the same or 
better
performance. It depends a lot on your system and application, but that is 
definitely a
possibility. As well as the fact that databases tend to grow and grow, and 
DB/2, unlike
traditional file based systems, can also partition the data in better ways, 
allowing you to
partition data for a particular system (or geographic location, or group of 
users, etc.) over
a particular set of volumes.

-Paul


----- Original Message -----
From: "Andy Nolen-Parkhouse" <aparkhouse@attbi.com>
To: <midrange-l@midrange.com>
Sent: Wednesday, May 01, 2002 5:35 AM
Subject: RE: iSeries Disk Pricing


> Friends,
>
> While it is good news that IBM is significantly reducing the price of
> their disk drives, for many workloads there may well be no change.  This
> announcement prices the 17 GB drives at exactly the old price of the 8
> GB drives ($1,400).  For those who require raw capacity, this represents
> a significant savings.
>
> For those of us who have routinely sized DB2-based transaction systems,
> frequently we end up configuring excess storage capacity in order to
> obtain an appropriate number of disk arms to ensure adequate
> performance.  This general rule applied for me in most systems using 8
> GB drives.  I needed the arms more than the capacity.  Because the 17 GB
> drives seem to have roughly the same rotational speed and seek times as
> the 8 GB drives, it stands to reason that a number of systems will
> require exactly the same number of drives at exactly the same price.
> There will be a significant increase in the amount of excess storage
> using the 17 GB drives, but the end result could well be no cost
> reduction.
>
> I'd welcome comment on this, but I think my reasoning is sound.  Some
> systems would be better served by reducing the cost of 8 GB drives
> rather than discontinuing them.
>
> I would prefer to be wrong because I'm trying to focus on the good news
> of the announcement, and there is a lot.
>
> Regards,
> Andy Nolen-Parkhouse
>
> > As to the specific question regarding disk, as part of this
> announcement
> > we
> > are announcing significant price reductions on 18 and 35 GB drives  -
> in
> > effect providing them at or near the same price as pSeries and the
> Unix
> > competition including HP and Sun.  This provides Fritz with the
> ability to
> > purchase and configure a set of disks at nearly the same price as our
> > pSeries system, with the added advantage of our integrated storage
> > management to do all of the disk and volume management most Unix
> customers
> > have to hire administrators for or purchase additional software for.
>
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