8 Parameter Management for Real Application Clusters Databases

This chapter describes server parameter file (SPFILE) placement and configuration in Real Application Clusters (RAC) environments. The topics in this chapter are:

Parameter Files and Real Application Clusters
Using Server Parameter Files in Real Application Clusters
Parameter File Search Order in Oracle Real Application Clusters
Server Parameter File Errors in Real Application Clusters

See Also:
Oracle Database Oracle Clusterware and Oracle Real Application Clusters Administration and Deployment Guide for more information about parameters and Oracle Real Application Clusters Deployment and Performance Guide for a discussion of parallel execution-related parameters in RAC data warehouse environments

Parameter Files and Real Application Clusters

Oracle uses parameter settings in parameter files to determine how to control various database resources. You can use two types of files for parameter administration: the server parameter file (SPFILE) or one or more traditional client-side parameter files.

Oracle recommends that you manage parameters using an SPFILE. If you use client-side parameter files, then Oracle does not preserve parameter changes made for self-tuning after shutdown.

Using Server Parameter Files in Real Application Clusters

By default, Oracle creates the server parameter file based on one SPFILE. You can change parameter settings in the server parameter file only by using Oracle Enterprise Manager or ALTER SYSTEM SET SQL statements; the server parameter file is a binary file that you should not edit.

Note:

Oracle recommends that you avoid modifying the values for self-tuning parameters; overriding these settings can adversely affect performance.

If you are upgrading from a previous Oracle release, then create and configure the server parameter file for RAC using the procedures described in the following section.

Location of the Server Parameter File

The default location of the server parameter file (SPFILE) when the database creates it from a PFILE is:

%ORACLE_HOME%\database\SPFILE%ORACLE_SID%.ORA

The default location of the server parameter file is inappropriate for RAC databases if you use ASM or raw devices because all instances must use the same server parameter file.

For Windows-based platforms Oracle recommends that you use a PFILE in this directory:

%ORACLE_HOME%\database\init%ORACLE_SID%.ora

This path is valid for each instance and it refers to a single, shared initialization parameter file. If you use raw storage, then the file must contain the following entry on a Windows-based platform:

SPFILE='\\.\dbname_SPFILE'

However, if you use a cluster file system, then use the following file location, where O is the OCFS drive:

SPFILE=O:\oradata\database_name\spfile.ora

If you use ASM, then the SPFILE value will be:

SPFILE='+disk_group_name/dbunique_name/spfiledbname.ora'

where dbunique_name is the unique database name and dbname is the database name.

Note:

The SPFILE for an ASM instance cannot be stored in ASM disks groups.

You must use the same value of SPFILE so that all instances use the same server parameter file at startup.

To use DBCA to create your database and to use the server parameter file, on the Initialization Parameters page select Create server parameter file (SPFILE) under the File Locations tab which is visible only if you are using raw storage. Then enter either a shared file system filename or the raw device path name in the Server Parameters Filename field.

Note:

When you use DBCA to create the server parameter file, the default PFILE file name is:

%ORACLE_HOME%\database\init%ORACLE_SID%.ora

This is the default PFILE name.

Parameter File Search Order in Oracle Real Application Clusters

Oracle searches for your parameter file in the following order:

%ORACLE_HOME%\database\spfilesid.ora
%ORACLE_HOME%\database\spfile.ora
%ORACLE_HOME%\database\initsid.ora

See the previous section, "Location of the Server Parameter File", for information on how to configure you system to prevent your RAC instances using inappropriate parameter files.

Server Parameter File Errors in Real Application Clusters

Oracle reports errors that occur during server parameter file creation or while reading the file during startup. If an error occurs during a parameter update, then Oracle records the error in your ALERT.LOG file and ignores subsequent parameter updates to the file. If this happens, then do either of the following:

Shut down the instance, recover the server parameter file, and restart the instance.
Restart the instance using a PFILE instead of the SPFILE.

Oracle displays errors for parameter changes that you attempt when you incorrectly use the ALTER SYSTEM SET statement. Oracle does this when an error occurs while reading from or writing to the server parameter file.