Depending on the options installed and the specific configuration of an Oracle installation, many background processes may be required. There is, however, a core set of background processes required for every Oracle instance, which are found in any machine on which Oracle is running, from Personal Oracle on an Intel-based PC to the largest Unix server. The failure of any one of these processes indicates failure of the entire Oracle instance; when such failures occur, the instance must be restarted.

The standard background processes include:

The following sections briefly describe these processes.