You need to configure Kobo Utilities (the calibre plugin) to perform the backup. The backup is stored locally on your computer. The backups are named based on their serial number and device type. So I have
Code:
KoboReader-KoboGlo-613A334012940-20140426-133131_CORRUPT.sqlite
KoboReader-KoboGlo-613A334012940-20141007-003337.sqlite
KoboReader-KoboGlo-613A334012940-20141007-003337.zip
...
KoboReader-KoboMini-N7052B4012703-20140515-091112.sqlite
...
KoboReader-KoboReader-000854E57EEE-20141103-211059.sqlite
KoboReader-KoboReader-000854E57EEE-20141103-211059.zip
...
KoboReader-KoboTouch-KG3172104949A-20140421-114540.sqlite
Backups can include both the database and (optionally) various configuration files (the version, affiliate.conf, Kobo eReader.conf, along with the contents of the .adobe-digital-edition folder).