About Instance Memory Structures

About Instance Memory Structures
The sizes of the instance memory structures affect database performance and are
controlled by initialization parameters.
Archiver (ARCn) Archiver processes copy the online redo log files to archival
storage when the log files are full or a log switch occurs. The
database must be in archive log mode to run archive processes.
For more information, see Chapter 9, "Performing Backup and
Recovery".
Manageability monitor
(MMON)
This process performs various management-related background
tasks, for example:
■ 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 (CJQ0
and Jnnn)
Job queue processes run user jobs, often in batch mode. A job is
a user-defined task scheduled to run one or more times.
See Also:
■ Oracle Database Reference for a complete list of Oracle Database
background processes
■ Oracle Database Concepts for an overview 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 configure the instance memory structures. If you choose
manual memory management, then Oracle Database provides advisors to help you
determine appropriate values for memory parameters.
The following sections describe the two important memory areas that you can monitor
and size:
■ System Global Area
■ Program Global Area
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