9Gb? Okay, even with 7Gb, it’s unlikely that your server has the RAM to generate a compressed file with that much data. It’s my guess that you’ll need to do partial backups of portions to get that much backed-up.
Saying that, how much of the 7GB are file types that will not change, i.e., videos, mp3’s, images, PDF’s and the like? You only need to back them up ONCE (and incrementally add to the backup directory when you add to the group).
I should note, too, that your image shows a directory OUTSIDE your webspace which is a good place (on your server) to park your backups. NOBODY can get to those files without access to your FTP account (or via a PHP script ON your server). However, if your server goes down, those files will do you no good at all. Best to have a backup offsite, too.