I keep two copies of my data -- at least I try to do that for the ones I care about like my mp3 files at home and my JDeveloper projects at work. One copy is on my local machine and the other on an other.one with a big hard disk. The command to do this is :
%> rsync -aruvzh /src_dir user@remote_machine_ip:/dest_dir
This will add all files and directories contained below src_dir excatly under dest_dir. If you need ti remove files not contained in src_dir from dest_dir as well use the --delete option. So the previous command becomes.:
%> rsync -aruvzh --delete /src_dir user@remote_machine_ip:/dest_dir
by the way, if you think that this is hard to remember and you need to do the synchronizing task often, then adding a line like
alias do_resync='rsync -aruvzh --delete /source_dir you@other_moahchine:/target_dir'
~/.bashrc file, might be the answer, or at least it was/is for me :-)