if you are comfortable with the command line you can try using hfspax and cron to automate your backups (works like a champ for me). also it's free
the latest hfspax version can be found, and downloaded, here:
http://www.versiontracker.com/moreinfo.fcgi?id=11144&db=mac
Once hfspax is installed, you'll need to decide where you want to backup the files to. In this example I am backing them up to a secondary hard drive named "Drive Two". In your case, just use the name of your scsi drive.
add the following lines to your /etc/crontab file:
#do some backups with hfspax. Users Dir daily at 1am and Applications every friday at 2am
0 1 * * * root hfspax -wvz -f /Volumes/Drive\ Two/backup/Users.pax -x cpio /Users
0 2 * * 5 root hfspax -wvz -f /Volumes/Drive\ Two/backup/Applications.pax -x cpio /Applications
save the etc/crontab file and you'll be off and running.
you can backup more than that, but I figure if I have to recover, I might as well start fresh
E