Data access layer (DAL) errors are identified by a file name of the form: Dal*.cpp.
For example: DalOracle.cpp, DalTeradata.cpp, DalMSSQL.cpp. They usually occur when the sensor fails to connect or execute a statement on the database. If the failure is critical, the sensor sends a message box notification (Error 9 - DAL_ERROR) to the server with details of the failure. These errors can also appear in the log in non-critical situations, such as when the database is shutting down or restarting. In such cases, it is best to examine the log and see if the situation is resolved once the database is up and running.
An error log indicating failure to delete the failed login trace during a database restart:
Sat Jun 14 2014 01:43:34.202 T[4016] F[DalMSSQL.cpp] L[1574] ERROR Failed to delete failed login trace [<INSTANCE NAME>]
Log line later on successful connection:
Sat Jun 14 2014 01:45:08.943 T[3760] F[DalMSSQL.cpp] L[1542] NOTICE Successfully switch off failed login trace [<INSTANCE NAME>]