Path: utzoo!utgpu!jarvis.csri.toronto.edu!helios.physics.utoronto.ca!ists!yunexus!maccs!cs4g6ag
From: cs4g6ag@maccs.dcss.mcmaster.ca (Stephen M. Dunn)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Problem: modem errors w/ disk cache
Message-ID: <25F7EF46.10711@maccs.dcss.mcmaster.ca>
Date: 9 Mar 90 18:00:38 GMT
References: <1421@oak8.UUCP> <42900066@uicsrd.csrd.uiuc.edu>
Reply-To: cs4g6ag@maccs.dcss.mcmaster.ca (Stephen M. Dunn)
Organization: McMaster University, Hamilton, Ontario
Lines: 24

In article <42900066@uicsrd.csrd.uiuc.edu> dkchen@uicsrd.csrd.uiuc.edu writes:
$	Well, I use the smartdrv of Windows as disk cache on extended memory.
$	I also noticed the bad block problem when using xmodem and ymodem.
$	Sometimes the error rate can go as high as 20%. However, I never had
$	any problem using these transmitted files even though errors were
$	reported. I use Avatex 2400 external modem, if that matters.

   The reason you never had any problems is that xmodem and ymodem are
error-resistant protocols.  When they detect an error in a packet, they
request that the transmitter re-send the packet.  Therefore, all bad
packets are thrown away and re-sent, leading to a final file which has
no errors in it.

   What should concern you is that when you get a 20% error rate, 20% of
your packets are being retransmitted so your downloads are taking quite
a bit longer than they would normally.  This may not matter for 50k files,
but if you're downloading a 500k file, for example, and you have a 20%
error rate, you end up spending the same time as it should take for a
600k file!
-- 
Stephen M. Dunn                               cs4g6ag@maccs.dcss.mcmaster.ca
          <std_disclaimer.h> = "\nI'm only an undergraduate!!!\n";
****************************************************************************
                   "Oooh yes I need some love" - Rush