Which three tasks are performed by background processes in an Oracle database instance?

Oracle background processes perform maintenance tasks for the database instance. The Listener Registration (LREG) process registers instance and service information with the listener. The Log Writer (LGWR) process is responsible for writing redo log entries from the redo log buffer to the online redo log files. The Database Writer (DBWn) process writes modified (dirty) data blocks from the database buffer cache to the data files on disk. These are all fundamental background process tasks.

A. The Oracle Net Listener, a separate process, creates dedicated server processes in response to client connection requests.
E. Reading data blocks from disk into the buffer cache is performed by foreground server processes at the request of a user session.

1. Oracle Database Concepts 23ai, Chapter 7, "Processes". The section "Background Processes" provides a detailed list and description of mandatory and optional background processes.

2. Oracle Database Concepts 23ai, Chapter 7, "Processes". The description for "Listener Registration Process (LREG)" states it registers information with the listener.

3. Oracle Database Concepts 23ai, Chapter 7, "Processes". The description for "Log Writer Process (LGWR)" states it writes redo log entries to disk.

4. Oracle Database Concepts 23ai, Chapter 7, "Processes". The description for "Database Writer Process (DBWn)" states its primary purpose is to write modified blocks from the buffer cache to data files.

5. Oracle Database Concepts 23ai, Chapter 7, "Processes". The section "Server Processes" explains that these processes fulfill user requests, which includes reading data blocks from disk into the SGA.