[plug] ADSL modem dropout while doing an rsync backup

[Steve Boak]

Hi All

I am having a weird problem with an ADSL connection - every time I try to do 
an rsync backup over the internet, the modem drops out and reconnects 
repeatedly every minute or so thereafter until it is hard reset by turning 
the modem power off and on again.

The backup script is a cron job on a remote machine, pulling data off the 
local server and storing it off-site at 3am every morning. Within one minute 
of the backup job starting, the modem on the local server has a hernia, and 
continues cycling until it is reset. 

There are no errors in the server logs, other than those caused by the network 
connection being down. It appears that compressed rsync data is upsetting the 
modem, but firstly that seems unlikely, and secondly I can't find any 
reference to anyone else having a similar problem.

Westnet log the fact that the connection has been lost and re-established, but 
nothing except the generic 'port error'. They are not much help after I 
mention the words "Linux" and "rsync"... :-)

This is a new backup job I am setting up, the two servers have been stable for 
several months. 

cron job start from auth.log:

Sep  2 03:01:21 www sshd[9154]: Accepted publickey for xxx from 
202.72.145 .xxx port 57942 ssh2

rsync command from bash script:

/usr/bin/rsync -a --delete --delete-excluded \
  --exclude outlook.pst xxx at nannuptc.org.au:/home/xxx \
  /media/backup/daily.$TODAY/ >> $LOG_TODAY 2>&1;

Snippet from Westnet's usage log:
     Login                  Logout                Time (mins)   Disconnect 
01/09/08 09:18:20  01/09/08 09:19:43    1          Port-Error
01/09/08 09:19:49  01/09/08 09:21:12    1          Port-Error
(power cycled here)
. . . .
(backup started here)
01/09/08 09:21:42  02/09/08 03:02:14    1060    Port-Error
02/09/08 03:02:24  02/09/08 03:03:47    1          Port-Error
02/09/08 03:03:51  02/09/08 03:05:34    1          Port-Error
02/09/08 03:05:37  02/09/08 03:07:00    1          Port-Error

Sever:		Linux 2.6.16.15 rsync version 2.6.4
ADSL Modem:	Iconnect Access 611

Remote:		Linux 2.6.20    rsync version 2.6.9

The problem still exists, but I've stopped using this method of backup until I 
resolve this strange issue.

Any ideas?

Steve


-- 
Steve Boak, (08) 9756 0662, P.O. Box 240, Nannup, WA 6275
Nannup Telecentre IT support, ph (08) 9756 3022
Engin (VoIP) number (08)64616187 (Local number in Perth)