Oracle Database Tips by Donald Burleson

Oracle10g Grid Computing with RAC
Chapter 8 - RAC Administration

Overview

Initialization parameters control the configuration of the database system. They are the key directives to start and manage any instance in the database. While launching the database instance, parameters are specified and they remain until the instance is shutdown. Optionally, certain parameters can be modified during the instance run time by the alter system set method, provided the instance has been started with the SPFILE method.

Before Oracle9i, Oracle instances were always started using a text file called an init.ora. This file is located by default in the $ORACLE_HOME/dbs directory. In Oracle9i, Oracle introduced the server parameter file (SPFILE), which is a binary file stored on the database server. We can start the instance in Oracle Database 10g using either the SPFILE or an init.ora file.

The SPFILE feature allows the change of parameter values dynamically. It also allows them to be set either permanently or in memory only. For Oracle Real Application Clusters (RAC), you can use one server parameter file and share it among instances. The usage of a single copy of the SPFILE for the entire database provides administrative convenience and simplification.

Many important values are specified by the initialization parameters, some of which include: