The background processes take care of the database. Depending on the options configured and the values specified in the Oracle initialization file, usually known as the INIT.ORA file, there can be from 6 to 50 or more background processes. Each background process has a specific responsibility to perform. See Chapter 10, for more details on their functions. Oracle created the background processes as separate entities to allow them to run independently of each other, performing their functions as needed and, if possible, simultaneously.

The INIT.ORA parameter SINGLE_PROCESS forces the background processes to run as one process. This is primarily used for system debugging with Windows NT. All of the INIT.ORA parameters are described in Chapter 12.