Re: New 270.

Hi,
Thanks everybody for the discussion.
It appears that the 8GB drives cost as much as the 17GB ones here as
well. So 8GB's are out.
>From a capacity point of view 4 17GB's are plenty. But after reading the
various responses I'm now seriously considering getting two more for
performance reasons.

In the current box I have 6 4GB drives (6607), the loadsource being
mirrored and the remaining 4 forming a raid set.

The real constraint (as always) is budgetary. If I get the additional
drives I'd definitely would want to get the 25G tape drive as well....

Best regards,
Matthias

>
> Your point is well taken.  I was being practical as opposed to
> theoretical.  If I was wrong in assuming that the model 400 currently
> had six or less drives, then the statement about duplicating the number
> of arms was not the best advice.  I would generally add arms until I
> reach some boundary, either the capacity of a disk enclosure or RAID
> controller.  In the case of a 270, this would be multiples of six.  Once
> the boundary is reached, then I would look more seriously at other
> options, including adding main storage.
>
> If I could get equal benefit from adding a 17GB drive or 512MB of main
> storage, I would add the drive.  A 17 GB drive will cost slightly less
> than the memory.  Two drives would cost more than the memory.  There are
> other benefits to adding memory and with the recent price decreases; it
> makes more and more sense to load up a system with excess memory.
>
> I agree that memory above the minimum will dramatically decrease the
> number of physical reads required on any system and can reduce the
> number of arms that would be required on a system with less memory.  I'm
> not sure that a system with a normal amount of batch throughput would
> consider 1 GB of main storage excessive to the point that database pages
> would consistently stay in memory.  It seems as though each release of
> all operating systems (not just OS/400) requires and uses more memory.
> I've worked in technical sales support for the AS/400 and have worked
> with a number of sales reps who have tried to lowball the hardware in
> order to sell the software.  Sometimes the customers decided to go along
> with the rep despite my efforts.  Because of this I have some
> unfortunate experience with undersized machines.  I have never seen a
> system with 20-30 users doing order entry and other interactive tasks
> survive with four drives, even with some excess memory.  I have seen it
> work with six.
>
> Mathias, how many drives do you currently have on your machine?
>
> The math on main storage works as follows.  The system 270-2431 has
> eight slots which will accept 256, 512, or 1,024 MB memory cards.  A
> single card may be installed; after the first they must be in matching
> pairs.  The 512 MB card is currently $1,792.  The 1,024 MB card is
> $3,584.  The 8.5 and 17 GB drives currently list for $1,400.
>

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Matthias Oertli   matthias.oertli@mdi.com.au