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About Instance Memory Structures

The sizes of the instance memory structures affect database performance and are controllcd by initialization parameters.

Archivcr (ARC//) Archiver processes copy the onlinc redo log files to archival storage when the log files are fuli or a log switch occurs. The database must be in archive log modę to run archivc processes.

For morę information, see Chapter 9, "Performing Backup and Recovery".

Manageability monitor (MMON)

This process performs various management-related background tasks. for cxample:

■Issuing alerts whenever a given metric violates its threshold value

■Taking snapshots by spawning additional processes

■Capturing statistical values for SQL objects that have been

recently modified

Job Queue Processes (CJQO

and Jnnn)

Job queue processes run uscr jobs. often in batch modę. A job is a user-defined task scheduled to run one or morę times.

See Also:

mOracie Database Reference for a complete list of Oracle Database background processes

mO racie Database Concepts for an overvicw of background processes

Table 5-1 (Cont.) Oracle Database Background Processes

Background Process Description

Overview of the Oracle Instance and Instance Management

Managing the Oracle Instance 5-5

Upon installation, you can let the database manage memory for you automatically, or you can choose to manually configurc the instance memory structures. If you choose manuał memory management. then Oracle Database provides advisors to help you determine appropriate values for memory parameters.

The following sections describe the two im port ant memory areas that you can monitor and size:

■System Global Area ■Program Global Area