Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!cernvax!jmg
From: jmg@cernvax.UUCP (john gerard)
Newsgroups: comp.unix.ultrix
Subject: Re: DS3100: restriction on no. of TTYs per LAT service
Keywords: DS3100, LAT
Message-ID: <1155@cernvax.UUCP>
Date: 27 Nov 89 07:35:33 GMT
References: <1152@cernvax.UUCP> <1989Nov25.015814.26839@cpd.com>
Reply-To: jmg@cernvax.UUCP (john gerard)
Organization: CERN European Laboratory for Particle Physics, CH-1211 Geneva, Switzerland
Lines: 43

In article <1989Nov25.015814.26839@cpd.com> neil@uninet.UUCP (Neil Gorsuch) writes:
>>We are trying to run a LAT service through a DS3100 on a lot of ttys.
>>We have configured 64 ttys with MAKEDEV, and we use ttys from tty04
>>for a lat/telnet service (actually a lat/tn3270 service). So far, so good.
>>If we configure too many of these ttys in the /etc/ttys file then at
>>some time the system goes bananas. Shells get continuously created and
>>destroyed (the lat/telnet service program calls in a shell script),
>>zombies abound, the CPU is 100% busy etc. etc.
>>I recall that some time ago someone talked about limitations on the number
>>of ttys per each multiple LAT service.
>
>If the problem is something in the LAT software, a possible solution
>is to use our SCSI serial/parallel servers.  From what I have been
>told of LATs (we don't have any to compare against), they have higher
>performance.  And they certainly cost a lot less than LATs and relieve
>a lot of ethernet load.  Plus you get a Centronics parallel port for
>each 8 serial ports.

Unless I have misunderstood, this solution sounds like asking me to buy
some extra equipment in order to get around a software bug.
However, I don't really understand it. We have lots of people who already
have their terminals on DECservers and who want one of their sessions to
go to an IBM. This is currently done by having a bank of reverse DECservers
with lines going into an IBM 7171 so as to get the 3270-VTxxx conversion.
I leave you to calculate the line cost of these reverse DECservers plus
cables plus 7171 ports! Where does this SCSI connection fit in?

What I want is to allow them to have a session through the DECstation,
which will do the 3270-VTxxx itself.

I can foresee a use for some kind of multiplexor to allow real physical
lines to hang off a DECstation (via SCSI I suppose), and would be happy
to have information on the "best" way to do this. However, it does not
solve my current problem.

Have I written a long enough follow-up such that it gets accepted?

I sure hope so.
-- 
 _ _  o |             __                    |    jmg@cernvax.uucp
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| | | | |_)  /_)     |  __/_) | (___\ | (_/ |  J. M. Gerard, Div. DD, CERN,
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