Initialization Parameter Files in Oracle

In order to start an instance and open the database, you must connect as SYSDBA and enter the STARTUP command. The Oracle server will then read the initialization parameter file and prepare the instance according to the initialization parameters contained within.

Note: You must have SYSDBA privilege.

Entries are specific to the instance being started

Two types of parameters:

• Explicit: Having an entry in the file
• Implicit: No entry within the file, but assuming the Oracle default values

To start an instance, the Oracle server reads the initialization parameter file. Two types of initialization parameter files exist:

• Static parameter file, PFILE, commonly referred to as initSID.ora.
• Persistent server parameter file, SPFILE, commonly referred to as spfileSID.ora.

Initialization Parameter File Contents

1. A list of instance parameters
2. The name of the database the instance is associated with
3. Allocations for memory structures of the System Global Area (SGA)
4. What to do with filled online redo log files
5. The names and locations of control files
6. Information about undo segments.

Multiple initialization parameter files can exist for an instance in order to optimize performance in different situations.

Using Oracle Enterprise Manager to View Initialization Parameters

From the OEM Console:

1. Navigate to Instance > Configuration.
2. Highlight Configuration.
3. Select All Initialization Parameters from the General tabbed page.