home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Columbia Kermit
/
kermit.zip
/
newsgroups
/
misc.19980901-19981211
/
000340_news@newsmaster….columbia.edu _Tue Nov 24 11:18:43 1998.msg
< prev
next >
Wrap
Internet Message Format
|
2020-01-01
|
7KB
Return-Path: <news@newsmaster.cc.columbia.edu>
Received: from newsmaster.cc.columbia.edu (newsmaster.cc.columbia.edu [128.59.35.30])
by watsun.cc.columbia.edu (8.8.5/8.8.5) with ESMTP id LAA04280
for <kermit.misc@watsun.cc.columbia.edu>; Tue, 24 Nov 1998 11:18:42 -0500 (EST)
Received: (from news@localhost)
by newsmaster.cc.columbia.edu (8.8.5/8.8.5) id LAA18078
for kermit.misc@watsun; Tue, 24 Nov 1998 11:18:42 -0500 (EST)
Path: news.columbia.edu!watsun.cc.columbia.edu!fdc
From: fdc@watsun.cc.columbia.edu (Frank da Cruz)
Newsgroups: comp.protocols.kermit.misc,de.alt.comm.mgetty
Subject: Re: At Wit's End on system freezes
Date: 24 Nov 1998 16:18:40 GMT
Organization: Columbia University
Lines: 113
Message-ID: <73em90$6ch$1@apakabar.cc.columbia.edu>
References: <365ACCF8.1C502662@ouray.cudenver.edu>
NNTP-Posting-Host: watsun.cc.columbia.edu
Xref: news.columbia.edu comp.protocols.kermit.misc:9547 de.alt.comm.mgetty:8190
In article <365ACCF8.1C502662@ouray.cudenver.edu>,
Joseph L. Kaiser <jlkaiser@ouray.cudenver.edu> wrote:
: This is addressed to whoever can help. I am at my wit's end. I am the
: systems administrator for a small medical transcription company in
: Golden, Colorado. We are running RedHat Linux 4.2 with the 2.23.30
: kernel. I have a set of four Zoom modems on a RocketPort 16 port PCI
: board; the modems are used for both dialout (sending completed work to
: clients) and dialin (receiving work from transcriptionists) and are on a
: rollover line so they are accessed in sequence. We are using "mgetty"
: 1.1.15 for the getty processes on all of the modems and we use Kermit
: 6.1 for all the dialout scripting and the dialin file transfer programs.
:
: The problem is, in short, that my system periodically freezes and it
: appears to be as a result of just Kermit or Kermit and mgetty.
:
To isolate the problem, you must separate Kermit and mgetty. My long
experience has told me that bidirectional terminal ports on Unix rarely
work as desired, and when problems such as this occur, they can almost
always be attributed to the bidirectionality. Remove that and the problems
go away.
I know this is not a very satisfying answer, since modems and phone lines
cost money, and so should be shared whenever possible.
: The history of the problem is this. We upgraded to RedHat 4.2 and a new
: ethernet network. The modems were attached to the serial ports of the
: nodes of the network (4) for various and sundry reasons. The system
: would freeze/crash so that I would have to reboot anywhere about every
: 3-10 days. We pulled the modems in July and put them all on the
: Rocketport on the main server. The system began to freeze about 1-5
: times a day and I had to reboot that often. I started to rule things
: out. I obtained the latest and greatest RocketPort driver. The
: behavior stayed the same. I played with the initialization strings in
: mgetty and the behavior stayed the same.
:
This is a critical area. There might very well be a setting that makes
the problem go away, but you didn't hit upon it in your experimentation.
For example, did you try all possible DSR-behavior selections? (&S0,
&S1, &S2, ...)
: In the middle of all this, I
: discovered that if I turned on and off the offending modem my system
: "unfroze" without rebooting. This saved a lot of time and frustration
: for all concerned.
:
Because it resets the modem to its factory or saved state, which agrees
with what mgetty and the port drivers need.
: I then sought to find out what made a modem an
: offending modem. It appears to boil down to Kermit file transfers.
:
What else are you using the modems for besides Kermit transfers?
: We serve approximately 14 hospitals and we dial in to those hospitals
: 3-4 time each every day. The scripts for doing this are automated.
: Frequently, a send will fail in some way, the login procedure won't go
: to completion, a prompt will be missed, or a file transfer will fail
: repeatedly, all of these require that the script be started over.
:
Of course the script can be written to catch and recover from all these
events.
: Sometimes when the script is restarted and the modem is then accessed
: the system freezes, as if the modem is already being used but no lock
: file exists.
:
When you say "the system freezes", do you mean the entire system, or do you
mean the process that is trying to open the modem? If you mean the whole
system, then there is a serious problem in the system itself, since no
user program should be able to freeze Linux.
: Also, it may fail if a send has left the modem in an
: unstable(?) state and someone connects to the modem rather than
: quitting.
:
If the Kermit process exits in the normal way, it will close the modem, hang
up the connection, release the lock, and restore the port driver to the
settings it had when the port was opened.
If Kermit terminates abnormally, i.e. crashes, then you should report that
to us. If it is terminated from outside abnormally -- killed from another
process, or suspended and then killed -- normal UNIX process-exit rules
apply, meaning, in most cases, that the port is simply closed.
It is almost always the case that the system freezes when we
: try to do something with a send that has stalled, i.e. when we try to
: get a C-Kermit prompt with our escape character or we try to connect to
: the modem. (By stalled I mean it looks like it has accessed the modem
: but it does not dial or initialize the modem.) If a send has stalled
: and I go to kill the process as root or the user kills the process, the
: system also freezes.
:
If Kermit is stuck in an i/o system call after successfully opening the modem,
this is probably a consequence of the state in which a previous incoming call,
or mgetty itself, has left the modem. There's not much Kermit can do about
this. Before Kermit can set up the modem for originating a call, the driver
has to allow i/o, but evidently this is not happening.
So again, my first recommendation would be to separate the inbound and
outbound modems. Configure the inbound modems for answering calls, and let
Kermit handle the outbound modems. Pay very careful attention to the modem
signal configurations on the modems (&Sn, &Cn, &Dn, etc), which MUST agree
in every respect with what your port drivers require.
Another idea would be to configure Kermit to:
set modem hangup-method rs232
and make sure the modem is set to hang up the connection and return to command
state when DTR drops (normally &D2), and use C-Kermit's "generic-high-speed"
modem type, whose init string is simply AT&F (reset to factor defaults).
- Frank