I am trying to backup my Ubuntu workstation by the help of this guide and are running into trouble as the tar command outputs

Exiting with failure status due to previous errors.

Here's what I ran in terminal:

sudo -i

cd /

tar -cvpzf sysbackup-20110821.tar.gz 

    --exclude=/sysbackup-20110821.tar.gz 

    --exclude=/proc 

    --exclude=/lost+found 

    --exclude=/sys 

    --exclude=/mnt 

    --exclude=/media 

    --exclude=/dev /

So from searching a bit, the error seems to be of a non-critical nature, but as I checkout the contents of the actual .tar file, my /home-folder is missing, so obviously something went clearly wrong.

What should I do instead to backup my system without errors?