You can see file-based information about your GPOs inside SYSVOL, and some people mistakenly believe that keeping a filesystem-level backup of that folder is all that they need to consider their GPOs backed up. While this file data could be useful, it is not the full picture. Log into your Domain Controller, and take a look at the following location: C:\Windows\SYSVOL\sysvol\mydomain.local (if you have configured your Domain Controller with something other than C:\Windows as %systemroot%, then navigate there instead).
Here, you will see a folder for Policies, one for Scripts, and one for StarterGPOs (if you followed along in Using a Starter GPO to build finalized GPOs and enabled Starter GPOs in your environment). This is ...