Oracle9i Database Administrator's Guide
Release 1 (9.0.1) for Windows

Part Number A90164-01
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Oracle9i Database Specifications for Windows

Oracle9i uses initialization parameters on Windows NT to enable various features of the database every time an instance is started.

This chapter contains these topics:

Initialization Parameter File (init.ora) Overview

An initialization parameter file is an ASCII text file containing parameters. By changing the parameters and values in an initialization file, you can specify, for example:

Every database instance has a corresponding initialization parameter file and ORACLE_SID registry parameter that points to the system identifier (SID) for the instance.

The initialization parameter filename takes the form init.ora. A single instance might have several initialization parameter files, each having some differences that affect system performance.

See Also:

  • Your init.ora file for initialization parameters set by Oracle Universal Installer during installation. These parameter settings may vary, depending on your hardware configuration.

  • Oracle9i Database Reference for descriptions of all initialization parameters and instructions for setting and displaying their values


Location of the Initialization Parameter File

By default, Oracle9i uses the initialization parameter files located in ORACLE_HOME\admin\db_name\pfile\init.ora, unless you specify a different initialization file with the PFILE option at database startup.

Editing the Initialization Parameter File

To customize Oracle9i database functions, you may need to edit the initialization parameter file. Only use an ASCII text editor to modify the file.

Sample File

A sample file called initsmpl.ora is located in the ORACLE_BASE\ORACLE_HOME\admin\sample\pfile directory.


If you create a database manually using a SQL script, you need to create an init.ora file or copy an existing init.ora file and modify the contents. If you use Oracle Database Configuration Assistant to create a database, the init.ora file is automatically created for you. 

If you want to use the sample initsmpl.ora file as part of database creation:

  1. Rename the file to init.ora.

  2. Edit this file to reflect the correct location of your database control files and the name of your database, as a minimum.

If you installed a starter database, the initialization parameter file init.ora used by the starter database is located in ORACLE_BASE\ORACLE_HOME\admin\sample\pfile. You can use either initsmpl.ora or the starter database init.ora as a basis for creating a new Oracle9i database initialization parameter file.

The annotated, sample initialization parameter file contains alternative values for the initialization parameters. These values and the annotations are preceded by comment signs (#), which prevent them from being processed. To activate a particular parameter, remove the preceding # sign. When you no longer want to use a particular parameter, edit the initialization parameter file to add a comment sign.

For example, several initialization parameters are specified with three different values to create small, medium, or large System Global Areas (SGAs), respectively. The parameter that creates a small SGA is active in the following example:

  db_block_buffers = 200		# SMALL 
# db_block_buffers = 550 # MEDIUM
# db_block_buffers = 3200 # LARGE

To create a medium-sized SGA, comment out the small parameter definition and activate the medium parameter definition. Edit the initialization parameter file as follows:

# db_block_buffers = 200		 # SMALL 
db_block_buffers = 550 # MEDIUM
# db_block_buffers = 3200 # LARGE

SGA_MAX_SIZE parameter

The SGA_MAX_SIZE parameter holds the maximum size that the System Global Area (SGA) component can reach for a particular instance. With this release, Oracle9i can change its SGA configuration while the instance is running. This allows the sizes of the buffer cache, the shared pool, and the large pool to be changed without shutting down the instance.

Oracle9i can start instances underconfigured and allow the instance to use more memory by growing the SGA components, up to a maximum of SGA_MAX_SIZE. If no SGA_MAX_SIZE value is specified, then Oracle selects a default value that is the sum of all components specified or defaulted at initialization time. If SGA_MAX_SIZE specified in init.ora is less than the sum of all components specified or defaulted to at initialization time, then the setting of SGA_MAX_SIZE in init.ora is ignored.

See Also:


The memory allocated for an instance's SGA is displayed on instance startup when using Oracle Enterprise Manager (or SQL*Plus). You can also display the current instance's SGA size by using the SQL*Plus SHOW statement with the SGA clause.

Initialization Parameters Without Windows NT-Specific Values

Oracle9i Database Reference describes the default values for many initialization parameters as being operating system-specific. However, not all the parameters that Oracle9i Database Reference describes as having operating system-specific values affect Windows NT. In these cases, Windows NT uses either the default value set in the Oracle9i kernel or does not use the parameter. Table 7-1 describes these initialization parameters:

Table 7-1 Initialization Parameters
Parameter  Description 


Not supported on Windows NT and should not be added to the initialization parameter file. 


Supported, but typically unnecessary due to Windows NT asynchronous I/O capabilities. 


Uses default value set in Oracle9i kernel (no Windows NT-specific value). 


Specifies whether Oracle includes the SGA in the core file for Oracle background processes. 


Specifies whether Oracle includes the SGA in the core file for foreground (client) processes. 


Specifies the directory where Oracle dumps core files. 


Oracle9i automatically sets value to number of CPUs available for your Oracle instance. 


Not applicable to Windows NT. 


Not applicable to Windows NT. 


Uses maximum value limited by available memory.  


Starter database uses value set in Oracle9i kernel (no Windows NT-specific value). The Custom database creation option of the Oracle Database Configuration Assistant enables you to customize the value for this parameter. 


Uses default value set in Oracle9i kernel (no Windows NT-specific value).  


Uses default value set in Oracle9i kernel (no Windows NT-specific value).  


Uses default value set in Oracle9i kernel (no Windows NT-specific value).  


Uses default value set in Oracle9i kernel (no Windows NT-specific value).  

Displaying Initialization Parameter Values

Windows NT-specific parameter values can be viewed by using an ASCII editor to open the ORACLE_BASE\ORACLE_HOME\admin\db_name\pfile\init.ora file. To display all parameter values (whether set in the init.ora file or the Oracle9i kernel), enter the following command at the SQL*Plus command prompt:

SQL> SHOW PARAMETER parameter_name

where parameter_name is the name of a specific initialization parameter.

The value for this parameter, whether defined in the ORACLE_BASE\ORACLE_HOME\admin\db_name\pfile\init.ora file or the Oracle9i kernel, displays on-screen.

Database Initialization Parameters

Check the following initialization parameters in Table 7-2 when creating a new database. They cannot be modified after you have created the database. See Chapter 1, "Postinstallation Database Creation" for details on creating a new database, including the part of the procedure when you modify these parameters.

Table 7-2 Database Initialization Parameters
Parameter  Description 

Specifies the database Globalization Support character set to use. This parameter can be set only when you create the database. 


Specifies the size in bytes of standard Oracle database blocks. 


Specifies the name of the database to be created. The database name is a string of eight characters or less. You cannot change the name of a database. 

1 Not an initialization parameter, but rather a clause in the CREATE DATABASE statement. See Chapter 1, "Postinstallation Database Creation" for an example of using this clause.

Calculating Database Limits

Use the size guidelines in Table 7-3 to calculate Oracle9i database limits.

Table 7-3 Block Size Guidelines
Type  Size 

Maximum block size 

16,384 bytes or 16 kilobytes (KB) 

Minimum block size 

2 kilobytes (KB) 

Maximum blocks per file 

4,194,304 blocks 

Maximum possible file size with 16 K sized blocks 

64 Gigabytes (GB)

(4,194,304 * 16,384) = 64 gigabytes (GB) 

Maximum number of files per database (depends on block size): 


  • 2 K sized blocks


20,000 files 

  • 4 K sized blocks


40,000 files 

  • 8 K sized blocks


65,536 files 

  • 16 K sized blocks


65,536 files 

Maximum file size for a FAT file 

4 GB 

Maximum file size in NTFS 

16 Exabytes (EB) 

Maximum database size 

65,536 * 64 GB equals approximately 4 Petabytes (PB) 

Maximum number of extents per database (depends on block size). Typical values are: 


  • 2 KB sized blocks


121 extents 

  • 4 KB sized blocks


255 extents 

  • 8 KB sized blocks


504 extents 

  • 16 KB sized blocks


1032 extents 

  • 32 KB sized blocks


2070 extents 

Shadow Process Memory: 


  • Release 9.0.1



  • Release 8.1.7


335 K 

  • Release 8.1.6


335 K 

  • Release 8.1.3


265 K 

  • Release 8.0.5


254 K 

  • Release 8.0.4


254 K  

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