code: func (s *Store) backupDB() error {
  	if os.Geteuid() != 0 {
  		return ErrDBUpdateNeedsRoot
  	}
  	backupsDir := filepath.Join(s.dir, "db-backups")
  	return backup.CreateBackup(s.dbDir(), backupsDir, backupsNumber)
  }
docs: // backupDB backs up current database.