The FolderGrid Appliance stores your encrypted file content in the S3 folder you created upon setup. All of the keys required to decrypt an manipulate your data are instead stored on the appliance filesystem both in configuration files and in the MySQL relational datastore.
You will need to design backup procedures this data according to your own needs and risk profile. Sophisticated administrators can easily configure a high-availability MySQL installation using multiple master/slave nodes by editing the appliance.conf file with the appropriate connection information.