How are the backup files stored? Are they stored as database files, normal files, or plain text?

CubeBackup does not just store Google Drive files, Gmail messages, Contacts and Calendar data - it also keeps metadata and version histories for files and folders. By default, everything is encrypted, and is not designed to be accessed outside of the application. If you need to view individual files or items from the backup, please refer to this doc.

Shared drives/Google Drive backups

Each Drive file will be backed up as <fileid_md5> in a subdivided directory, along with any corresponding metadata files. A single Drive file may have multiple metadata files which trace its version history and modifications. Drive directories are also backed up as metadata files.

Google-native Drive files, such as Google Documents, Google Spreadsheets, or Google Slide files, may also have .export files along with their backups.

SQLite database files are used to trace the history versions of the Drive files and folders.

Google Drive files backup structure

Gmail backups

Each Gmail message is backed up as <mail_id> and stored as a raw mail file (text files with BASE64-encoded attachments). Similar to Drive files, Gmail messages are also put in subdivided directories to accelerate file access.

SQLite database files are used to keep metadata for the Gmail backups.

Contacts backups

Google Contacts data is backed up as SQLite files.

Calendar backups

Google Calendar events are backed up as SQLite files.

Note: By default, all backed up data, including the SQLite database files, is encrypted. Even an administrator cannot view the contents of the files directly.