We strongly recommend System DSNs so that the DSN is visible to MARS even when the user associated with the DSN is logged off.
All communication to databases (including Access databases) is done through ODBC, so you must setup a system DSN to the database before you can use this facility.
When setting up DSNs we recommend (if possible) that you use Windows Authentication (Trusted Connection). This ensures that your username and password are not required to be stored in MARS (more secure) and overcomes a large number of security restrictions which Windows places on DSNs.
When using Windows Authentication, make sure that the MARS NT Service user (or background application service user) has full rights to the database otherwise, though you will connect when you are logged in, automated scheduling will fail if the Service user has not got rights to the database.
When setting up a DSN to a SQL server, you must ensure that the "Default Database" setting is set to the database you are connecting to (Windows defaults this to "Master").