S file in DBA
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Objectives
After completing this lesson, you should be able to do the following:
Create and manage initialization parameter files
Start up and shut down an instance
Monitor and use diagnostic files
Initialization Parameter Files
Initialization Parameter Files
To start an instance, the Oracle server must read the initialization parameter file.
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
Multiple initialization parameter files can exist
Changes to entries in the file take effect based on the type of initialization parameter file used
Static parameter file, PFILE
Persistent parameter file, SPFILE
Initialization Parameter Files
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 parameter file, SPFILE, commonly referred to as spfileSID.ora.
Initialization parameter file contents:
A list of instance parameters
The name of the database the instance is associated with
Allocations for memory structures of the System Global Area (SGA)
What to do with filled online redo log files
The names and locations of control files
Information about undo segments
Multiple initialization parameter files can exist for an instance in order to optimize performance in different situations.
Initialization Parameter Files
Using Oracle Enterprise Manager to View Initialization Parameters
From the OEM Console:
1. Navigate to Databases > Instance > Configuration.
Select All Initialization Parameters from the General page.
PFILE initSID.ora
Text file
Modified with an operating system editor
Modifications made manually
Changes take effect on the next startup
Only opened during instance startup
Default location is $ORACLE_HOME/dbs
PFILE
The PFILE is a text file that can be maintained using a standard operating system editor. The PFILE is read only during instance startup. If the file is modified, the instance must be shut down and restarted in order to make the new parameter values effective.
By default, located in the $ORACLE_HOME/dbs directory and named initSID.ora.
Creating a PFILE
A sample init.ora file is created by the Universal Installer during installation. This sample init.ora file can be used to create an instance-specific initSID.ora. A text editor can be used to modify the parameters within the initSID.ora file.
# Initialization Parameter File: initdba01.ora
db_name = dba01
instance_name = dba01
control_files = ( home/dba01/ORADATA/u01/control01dba01.ctl,
home/dba01/ORADATA/u02/control01dba02.ctl)
db_block_size = 4096
db_cache_size = 4M
shared_pool_size = 50000000
java_pool_size = 50000000
max_dump_file_size = 10240
background_dump_dest = /home/dba01/ADMIN/BDUMP
user_dump_dest = /home/dba01/ADMIN/UDUMP
core_dump_dest = /home/dba01/ADMIN/CDUMP
undo_management = AUTO
undo_tablespace = UNDOTBS
. . .
PFILE Example
Specify the values in the following format: keyword=value.
The server has a default value for each parameter. This value may be operating system dependent, depending on the parameter.
Parameters can be specified in any order, although there are some exceptions.
Comment lines begin with the # symbol.
Enclose parameters in double quotation marks to include character literals.
Additional files can be included with the keyword IFILE.
If case is significant for the operating system, then it is also significant in filenames.
Multiple values are enclosed in parentheses and separated by commas.
Note: Develop a standard for listing parameters; either list them alphabetically or
group them by functionality. The PFILE varies from instance to instance and does not
necessarily look like the preceding example.
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