RE: New 270. -- MIDRANGE-L

Matthias,

If you're buying new equipment from IBM, you may as well get the 17 GB
drives because they cost exactly the same as the 8.5 GB drives and have
identical performance characteristics.  I don't think that they are
discontinuing the smaller drives because of problems, rather because it
costs just about as much to make either one and it is easier to
manufacture less variety.

That said, I would suggest duplicating the number of arms from your
model 400 on the 270, assuming performance is adequate (or at least not
I/O-bound).  This may mean that you are swimming in excess capacity, but
it is really the arm-count which will drive your performance rather than
gigabytes of storage.  How many arms on your current machine?  Have you
added drives for capacity?  If you are moving your workload as is from
the 400 to the 270, then you should be able to capture a performance
monitor sample from your machine at peak load and then ask your vendor
to model that workload on Best/1 in IBM's performance tools.  This
software does a good job of calculating disk-arm requirements.  The 270
has support for up to six drives in the base chassis.  After six you buy
an expansion cage for an additional six.  If you can hold it to six
drives, you will keep your costs lower.

One GB of main storage should be adequate for the workload you describe.

The newer QIC drives (1/4 inch) are considerably faster and some of the
annoying pre-tensioning rigmarole has been eliminated.  It's a good
economical choice.  I don't know which specific capacities are the best
deals for QIC these days; you have a choice of 16 GB or 25 GB.  Check
for compatibility with your old saves if that is necessary.

You mention that you use 'some green screens and telnet' in your current
installation.  This implies that you already have a twinax
infrastructure and would duplicate it on the 270.  In this case, the
console decision is really a matter of preference.  There are some nifty
things which you can do with a PC console, particularly having remote
access to the control panel.  But you do sacrifice some reliability and
potential installation snafus.  If you do go with a PC console, then you
will have a Windows PC available and could use that to run Operations
Navigator.

You're right, you should budget for a Windows-based PC for Ops Nav.,
whether you use it as a console or not.  You may find that with more
powerful hardware, you may want to implement some things which can only
be configured using that tool.  I'd suggest Windows 2000 Professional
for console and/or Ops Nav. Workstation.

You're really on your own with the console choice.  I've had good
experiences with PC Consoles and have never had a problem once they're
installed.  However, I have had some major battles getting them
initially installed and configured.  If you are buying a twinax card
anyway, you may be able to order the machine configured for PC Console,
and then reconfigure the system for twinax console if you have problems.
(Please double-check this last statement with your vendor, I'm
hesitating a bit here.)

Hope this helps,
Regards,
Andy Nolen-Parkhouse


> Subject: New 270.
>
> Hi,
>
> We're looking to replace our 9402-400 (2131) with a 9406-270 (2431).
> The box supports about 20-30 users with mostly interactive work (order
> entry, etc.). The software is plain CL/RPG III. We use some green
> screens and telnet to access the box.
>
> I'd like to ask a couple of questions with regards to the
> configuration:
>
> - 1GB main storage, is this adequate?
>
> - Disk arms: I'm looking at getting 4 17GB disks. Another option would
> be to get 6 8GB disks in order to spread the load over more arms. But
> from what I hear, IBM is going to discontinue the 8GB drives shortly
> due to problems. How badly will having just 4 arms impact performance?
> Are the 17GB's the right choice (performance wise)?
>
> - It was suggested I get a 16GB quarter-inch tape drive (4583). Is
> this a good choice? We currently have an 8mm drive (6390) and a
> quarter-inch 2.5GB drive (6380) which is rarely used (too slow).
>
> - The sales guy is pushing an ops-console but I prefer twinax. Should
> I give in?
>
> One more thing: It appears that a lot of configuration functions have
> been moved to Ops Navigator exclusively which from what I hear is
> windows only. If this is true, we have a problem because we run mostly
> linux workstation. Do I need to factor in getting a Windows PC?
>
> I'd love to be able to testdrive this stuff.... it's hard choosing of
> 'the plan'.
>
> Any suggestions are most welcome.
> Best regards,
> Matthias
>
> --
>
> ---------------------------------------------------------------------
> Matthias Oertli   <matthias.oertli@mdi.com.au>
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