A resource group is a container to which you add resources that you want to back up and protect together. A resource group enables you to back up all of the data that is associated with a given application simultaneously. A resource group is required for any data protection job. You must also attach one or more policies to the resource group to define the type of data protection job that you want to perform and the protection schedule.
You can back up a database or Database Availabililty Group (DAG) individually, on demand, without creating a new resource group.
A resource group cannot contain more than one DAG.