def create_db_instance(identifier, instance_class, allocated_storage, master_username, master_password, options={})
params = {}
params['DBInstanceIdentifier'] = identifier
params['DBInstanceClass'] = instance_class
params['AllocatedStorage'] = allocated_storage
params['MasterUsername'] = master_username
params['MasterUserPassword'] = master_password
params['Engine'] = options[:engine] || "MySQL5.1"
params['DBName'] = options[:db_name] if options[:db_name]
params['AvailabilityZone'] = options[:availability_zone] if options[:availability_zone]
params['PreferredMaintenanceWindow'] = options[:preferred_maintenance_window] if options[:preferred_maintenance_window]
params['BackupRetentionPeriod'] = options[:preferred_retention_period] if options[:preferred_retention_period]
params['PreferredBackupWindow'] = options[:preferred_backup_window] if options[:preferred_backup_window]
@logger.info("Creating DB Instance called #{identifier}")
link = do_request("CreateDBInstance", params, :pull_out_single=>[:create_db_instance_result, :db_instance])
rescue Exception
on_exception
end