Ubuntu / Apple :: Backing Up Compressed File To An External Hardrive?

I am attempting to be careful in case my system crashes, and although highly unlikely my first question is if there is a way to first compress my Linux Partitions. After running the diskutil command in OSX's Terminal, I basically end up with this poartition scheme:

Quote:
Macintosh HD = 130GB
disk0s3 = 1MB
disk0s4 = 30GB
Linux Swap = 1.3 GB

I am sure there is a way in the Terminal to first compress disk0s3, disk0s4, and Linux Swap, and then output the compressed partitions into my external Harddrive. I have already read some of the suggestions that only /HOME, /etc/fstab/, list of installed packages, /opt, and /var/cache/apt/archives/-where all installed packages are stored, is what I should backup. But, please correct me if I'm wrong. Wouldn't it take quite a while to install all those packages again in case of a system failure. Or would it just be easier to untar all of them in their directories once Linux has been reinstalled. The closest command I have found so far in being able to achieve this is:

Quote:

sudo tar cvf - files | (cd target_directory ; tar xpf -) The above code is very suitable for what I am looking for because it enables you to copy files into another location by using the tar command where you would create In my case the new location would be my external harddrive. My external harddrive already has its own Linux partition which I am able to mount in Linux and that Linux sees as free space.