Re: LRZSZ

[Andy Holyer]

On 9 Jul 2004, at 21:55, Alex Mitchell wrote:
A very large automotive supplier (our client) uses HHP Dolphin 7200 
scanners to scan their automotive crates.  The scans are batched in 
the scanners.  When they are ready to upload the data to our server, 
they dock the scanner in the cradle.  The cradle is connected to a 56K 
US Robotics modem.  We wrote the scanner application using 16bit C 
compiler (because the scanners are DOS based).  We're using a Y-Modem 
protocol to upload the data files.  The scanner dials into a modem 
pool to upload the data.  When a connection is established, LRZ is 
used to receive the data files from the scanner.  With smaller files 
(7K and smaller), this works fine.  I've tried uploading a 12K file.  
After uploading 8K, the scanner returns an NAK error.  This error 
keeps repeating until the scanner gives up and the upload fails.  I've 
tried a 24K file, it fails after 16K.  I've tried a 56K file and it 
fails at 16K.  NAK error each time.  I've tried the above scenario on 
FreeBSD 4.7 and FreeBSD 5.2.1 about 30 times for each file size, with 
the exact same result each time.
I had a very similar problem about 10 years ago. Macs trying to send 
mail just hung when they had more than x lines of text.

It turned out in the end that the then MacOs TCP/IP stack was ignoring 
the stated MTU, and just tried to send the whole thing in one huge 
packet. On dial-up, this overflowed the kernel IO buffer size,  and  
hung the process.

In the end I looked at the serial port handling code in the kernel, and 
the buffer size was sensible for a 1990-era machine with 64MB of ram, 
being about 1K each. Since we had plenty of RAM on the boxes, I 
sacrificed a bit by upping the buffer size define to something big (I 
think 64K), rebuilt the kernel and the problem went away.

I wonder if something similar is happening to you?
---
Andy Holyer, Technical stuff
Hedgehog Broadband, 11 Marlborough Place Brighton BN1 1UB
08451 260895 x 241
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LRZSZ

[Alex Mitchell]

I am experiencing a major problem with LRZ on FreeBSD.  I have tried it on FreeBSD 4.7 
and FreeBSD 5.2.1.  I am using LRZ version 0.12.20.  Here's the scenario.
A very large automotive supplier (our client) uses HHP Dolphin 7200 scanners to scan 
their automotive crates.  The scans are batched in the scanners.  When they are ready 
to upload the data to our server, they dock the scanner in the cradle.  The cradle is 
connected to a 56K US Robotics modem.  We wrote the scanner application using 16bit C 
compiler (because the scanners are DOS based).  We're using a Y-Modem protocol to 
upload the data files.  The scanner dials into a modem pool to upload the data.  When 
a connection is established, LRZ is used to receive the data files from the scanner.  
With smaller files (7K and smaller), this works fine.  I've tried uploading a 12K 
file.  After uploading 8K, the scanner returns an NAK error.  This error keeps 
repeating until the scanner gives up and the upload fails.  I've tried a 24K file, it 
fails after 16K.  I've tried a 56K file and it fails at 16K.  NAK error each time.  
I've tried the above scenario on FreeBSD 4.7 and FreeBSD 5.2.1 about 30 times for each 
file size, with the exact same result each time.

I've tried the exact same setup on Linux RH 9 and it works every time.  No problems 
uploading files as big as 100K.

I am a big advocate of FreeBSD.  We currently use it on about 8 servers.  I don't want 
to have to switch to Linux.  However, if that is the only choice that I have, then 
that's the only choice I have.

If I could speak to someone about this issue, or be directed to some help, I would 
really appreciate it.  Please reply to this email and I'll send my toll-free number.  
I would really like to keep using FreeBSD to support all of our applications.  Any 
assistance would be greatly appreciated.
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