Resume RSYNC over SSH after broken connection?

Question

I have to transfer large amounts of data (>80 GB) over ssh using rsync. Everything is working fine, but the DSL connection where the backup data is sent from will drop once every 24h for up to 3 minutes (switching providers is not an option).

How do I:

1. Automatically restart the transfer when the connection is back up?

2. Make sure there are not by accident two rsync commands running at the same time?

Answer 1

The following should be helpful:

#!/bin/bash

while [ 1 ]
do
    rsync -avz --partial source dest
    if [ "$?" = "0" ] ; then
        echo "rsync completed normally"
        exit
    else
        echo "Rsync failure. Backing off and retrying..."
        sleep 180
    fi
done

When the connection dies, rsync will quit with a non-zero exit code. This script simply keeps re-running rsync, letting it continue until the synchronisation completes normally.