For the database, the SAP system is a single user, SAP<SAPSID>, or SAPR3 whose password is stored in the table SAPUSER. Therefore, to access the database, the SAP system uses a mechanism called the OPS$ mechanism, which works as follows:
1. When the system accesses the database, it first logs on to the database as the user OPS$<operating_system_user>, for example, OPS$<domain>\<sapsid>adm. (The OPS$ user that corresponds to the operating system user must be defined in the database and identified as externally.)
SAP does not support changes of the Oracle parameter os_authent_prefix whose default value is OPS$.
2. It retrieves the password for SAP<SAPSID> or SAPR3 from the SAPUSER table.
3. It then logs on to the database as the user SAP<SAPSID> or SAPR3.