May I ask why you want to back up the entire system?
To back up the entire system, as papibe said, use CloneZilla. It's fast and thorough.
But I wouldn't bother, because if you totally break your system, it's quicker to reinstall especially if your /home is on a separate partition; if it's not, restore your entire /home folder after reinstalling.
For backing up your data, I recommend looking at rdiff-backup. It uses rsync (so it's fast except for the very first time you back up), but it has the ability to keep previous versions, either indefinitely or for a set period; and you can fine-tune what is backed up. I back up my entire /home folder (for me and everyone else who uses the computer, so I use sudo) with rdiff-backup every day and it takes just 5-15 minutes depending on just how much has changed.
Exclude the following folders when backing up:
And, of course, any others that you want excluded.