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19990510: advice

>From: Bill Fingerhut <address@hidden>
>Organization: LSC
>Keywords: 199905101610.KAA28438 X server software

Hi Bill-

>I don't know the source, but someone has suggested that we
>make substantial changes to our metlab. A test is to be
>conducted this week to convince us that the idea will work.
>I hate to make a big decision on the sole basis of what I
>can see. So, I am asking you to please advise me of any
>information that I should also consider.
>
>The idea is to have each workstation run Windows NT; run all
>Unidata applications on the server; use  X server viewer 
>on each workstation.

The drawbacks to this are sometimes not having enough colors
on the NT workstations and the load on the server.  Try using
displays that have lots of colors.  Especially make sure that
all the GEMPAK applications will work in this mode.

You also need a way of logging in from each workstation with
a different account so there are not conflicts.  You _CANNOT_
use the same account on all the workstation to run McIDAS.

>The test is to display a McIDAS satellite loop on 10 work-
>stations simultaeously, to see if the server can handle
>the load.
>
>Do you know of any site that is configured this way?

Plymouth State is set up in this way to do displays of McIDAS-X
and WXP.  I don't know if they are also using GEMPAK on their
Win95 workstations.  I also think Univesity of Arizona might be
doing this as well.

>Do you think it has merits?

I think it is a tradeoff of one type of administration for another.
You lose having to administer the Unix systems on the clients, but
gain the X and Windows NT administration.  Plus, Unix is a much more
stable operating system than WindowsNT.  Might see more "three fingered
salutes" under NT.  You are going to need a pretty powerful server
to serve 10 workstations.  It will need a lot of shared memory and
physical memory. There will also be considerable network traffic.

>Do you think there are any serious drawbacks or pitfalls?

Other than the ones above, no.  Also, we don't have easy ways of
supporting this configuration if you run into problems.  We don't use
X-Server software.  You might see a performance hit with the network
traffic and disk activity on the server.

>What should I ask, etc?

Let the loops run for a long time and overlay data on top.  Also,
have all the systems start loading the loops at the same time
and then load a different loop to see how things bog down.  With
McIDAS, the memory is preallocated when you start the session so
there is no (or little) new memory needed after the session starts.
With GARP, memory is allocated as needed, so the more frames you loop,
the greater the load on the server.  I would strongly advise you
to try running GARP on all machines at the same time with long loops.
Also, the X server will need to be run in 8-bit mode for GEMPAK
and McIDAS to work correctly.

We'd be interested in hearing the results of your test especially
if it works.  In particular, what are you using for a server and
what X-Window software are you using.

Don
*************************************************************
Don Murray                               UCAR Unidata Program
address@hidden                        P.O. Box 3000
(303) 497-8628                              Boulder, CO 80307
*************************************************************
Unidata WWW Server               http://www.unidata.ucar.edu/
McIDAS Demonstration Machine  http://mcdemo.unidata.ucar.edu/
*************************************************************