Managing Initialization Parameters Using a Server Parameter File

What Is a Server Parameter File?

A server parameter file can be thought of as a repository for initialization parameters that is maintained on the machine running the Oracle Database server. It is, by design, a server-side initialization parameter file. Initialization parameters stored in a server parameter file are persistent, in that any changes made to the parameters while an instance is running can persist across instance shutdown and startup. This arrangement eliminates the need to manually update initialization parameters to make persistent any changes effected by ALTER SYSTEM statements. It also provides a basis for self-tuning by the Oracle Database server.

A server parameter file is initially built from a text initialization parameter file using the CREATE SPFILE statement. (It can also be created directly by the Database Configuration Assistant.) The server parameter file is a binary file that cannot be edited using a text editor. Oracle Database provides other interfaces for viewing and modifying parameter settings in a server parameter file.

When you issue a STARTUP command with no PFILE clause, the Oracle instance searches an operating system–specific default location for a server parameter file from which to read initialization parameter settings. If no server parameter file is found, the instance searches for a text initialization parameter file. If a server parameter file exists but you want to override it with settings in a text initialization parameter file, you must specify the PFILE clause when issuing the STARTUP command. Instructions for starting an instance using a server parameter file are contained in "Starting Up a Database".

Migrating to a Server Parameter File

If you are currently using a text initialization parameter file, use the following steps to migrate to a server parameter file.

1. If the initialization parameter file is located on a client machine, transfer the file (for example, FTP) from the client machine to the server machine.

   Note:

   If you are migrating to a server parameter file in an Oracle Real Application Clusters environment, you must combine all of your instance-specific initialization parameter files into a single initialization parameter file. Instructions for doing this and other actions unique to using a server parameter file for instances that are part of an Oracle Real Application Clusters installation are discussed in Oracle Real Application Clusters Administration and Deployment Guide and in your platform-specific Oracle Real Application Clusters Installation Guide.

2. Create a server parameter file in the default location using the CREATE SPFILE FROM PFILE statement. See "Creating a Server Parameter File" for instructions.

   This statement reads the text initialization parameter file to create a server parameter file. The database does not have to be started to issue a CREATE SPFILE statement.

3. Start up or restart the instance.

   The instance finds the new SPFILE in the default location and starts up with it.

Creating a Server Parameter File

You use the CREATE SPFILE statement to create a server parameter file. You must have the SYSDBA or the SYSOPER system privilege to execute this statement.

The CREATE SPFILE statement can be executed before or after instance startup. However, if the instance has been started using a server parameter file, an error is raised if you attempt to re-create the same server parameter file that is currently being used by the instance.

You can create a server parameter file (SPFILE) from an existing text initialization parameter file or from memory. Creating the SPFILE from memory means copying the current values of initialization parameters in the running instance to the SPFILE.

The following example creates a server parameter file from text initialization parameter file /u01/oracle/dbs/init.ora. In this example no SPFILE name is specified, so the file is created with the platform-specific default name and location shown in Table 2-3.

CREATE SPFILE FROM PFILE='/u01/oracle/dbs/init.ora';

The next example illustrates creating a server parameter file and supplying a name and location.

CREATE SPFILE='/u01/oracle/dbs/test_spfile.ora'
       FROM PFILE='/u01/oracle/dbs/test_init.ora';

The next example illustrates creating a server parameter file in the default location from the current values of the initialization parameters in memory.

CREATE SPFILE FROM MEMORY;

Whether you use the default SPFILE name and default location or specify an SPFILE name and location, if an SPFILE of the same name already exists in the location, it is overwritten without a warning message.

When you create an SPFILE from a text initialization parameter file, comments specified on the same lines as a parameter setting in the initialization parameter file are maintained in the SPFILE. All other comments are ignored.

Oracle recommends that you allow the database to give the SPFILE the default name and store it in the default location. This eases administration of your database. For example, the STARTUP command assumes this default location to read the SPFILE.

Table 2-3 shows the default name and location for both the text initialization parameter file (PFILE) and server parameter file (SPFILE) for the UNIX, Linux, and Windows platforms. The table assumes that the SPFILE is a file. If it is a raw device, the default name could be a logical volume name or partition device name, and the default location could differ.

If you create an SPFILE in a location other than the default location, you must create a text initialization parameter file that points to the server parameter file. For more information, see "Starting Up a Database".

Storing the Server Parameter File on HARD-Enabled Storage

Starting with Release 11g, the server parameter file (SPFILE) is in a new format that is compliant with the Oracle Hardware Assisted Resilient Data (HARD) initiative. HARD defines a comprehensive set of data validation algorithms, implemented at both the software and storage hardware levels, to ensure that no corrupt data is written to permanent storage. To fully enable HARD protection for the data in your SPFILE, the SPFILE must reside on HARD-enabled storage, and compatibility for your database instance must be advanced to at least 11.0.0.

You can store the HARD-compliant SPFILE on non-HARD-enabled storage. In this case, the new SPFILE format supports only detection of corrupt SPFILE data. Storing the SPFILE on HARD-enabled storage prevents corrupt data from being written to storage in the first place.

For more information about HARD, and for a list of storage vendors that supply HARD-enabled storage systems, visit: http://www.oracle.com/technology/deploy/availability/htdocs/HARD.html.

Follow these guidelines for full HARD protection when installing or upgrading your Oracle database:

When Installing or Initially Creating a Release 11g Database

When first installing or creating a Release 11g database, the COMPATIBLE initialization parameter defaults to 11.1.0, so this requirement for a HARD-compliant server parameter file (SPFILE) is met. You must then ensure that the SPFILE is stored on HARD-enabled storage. To meet this requirement, do one of the following:

• For an Oracle Real Application Clusters environment without shared storage, when DBCA prompts for the location of the SPFILE, specify a location on HARD-enabled storage.

• For a single-instance installation, or for an Oracle Real Application Clusters environment with shared storage, complete these steps:

  1. Complete the database installation with Database Configuration Assistant (DBCA).

     The SPFILE is created in the default location. See Table 2-3 for information on default locations.

  2. Do one of the following:

     • Using an operating system command, copy the SPFILE to HARD-enabled storage.

     • In SQL*Plus or another interactive environment such as SQL Developer, connect to the database as user SYS and then submit the following command:

       CREATE SPFILE = 'spfile_name' FROM MEMORY;
       

       where spfile_name is a complete path name, including file name, that points to HARD-enabled storage.

  3. Do one of the following:

     • Create a text initialization parameter file (PFILE) in the default location with the following single entry:

       SPFILE = spfile_name
       

       where spfile_name is the complete path to the SPFILE on HARD-enabled storage.

     • On the UNIX and Linux platforms, in the default SPFILE location, create a symbolic link to the SPFILE on HARD-enabled storage.

     See Table 2-3 for default name and location information for PFILEs and SPFILEs.

  4. Shut down the database instance.

  5. Delete the SPFILE in the default location.

  6. Start up the database instance.

When Upgrading to Release 11g from an Earlier Database Release

When upgrading to Release 11g from an earlier database release, complete these steps to migrate your SPFILE to the HARD-compliant format and to store the SPFILE on HARD-enabled storage:

1. Start SQL*Plus or another interactive query application, log in to the database as user SYS or SYSTEM, and then enter the following command:

   ALTER SYSTEM SET COMPATIBLE = '11.1.0' SCOPE = SPFILE;
   

   WARNING:

   Advancing the compatibility level to 11.1.0 enables Release 11g features and file formats and has wide repercussions. Consult Oracle Database Upgrade Guide before proceeding.

2. Restart the database instance.

   The database is now at compatibility level 11.1.0.

3. If your SPFILE is not already on HARD-enabled storage, complete the following steps:

   1. In SQL*Plus or another interactive environment, connect to the database as user SYS and then submit the following command:

      CREATE SPFILE = 'spfile_name' FROM MEMORY;
      

      where spfile_name is a complete path name, including file name, that points to HARD-enabled storage.

   2. Do one of the following:

      • Create a text initialization parameter file (PFILE) in the default location with the following single entry:

        SPFILE = spfile_name
        

        where spfile_name is the complete path to the SPFILE on HARD-enabled storage.

      • On the UNIX and Linux platforms, in the default SPFILE location, create a symbolic link to the SPFILE on HARD-enabled storage.

      See Table 2-3 for default name and location information for PFILEs and SPFILEs.

   3. Shut down the database instance.

   4. Delete the SPFILE in the default location.

   5. Start up the database instance.

The SPFILE Initialization Parameter

The SPFILE initialization parameter contains the name of the current server parameter file. When the default server parameter file is used by the database—that is, you issue a STARTUP command and do not specify a PFILE parameter—the value of SPFILE is internally set by the server. The SQL*Plus command SHOW PARAMETERS SPFILE (or any other method of querying the value of a parameter) displays the name of the server parameter file that is currently in use.

Changing Initialization Parameter Values

The ALTER SYSTEM statement enables you to set, change, or restore to default the values of initialization parameters. If you are using a text initialization parameter file, the ALTER SYSTEM statement changes the value of a parameter only for the current instance, because there is no mechanism for automatically updating text initialization parameters on disk. You must update them manually to be passed to a future instance. Using a server parameter file overcomes this limitation.

There are two kinds of initialization parameters:

• Dynamic initialization parameters can be changed for the current Oracle Database instance. The changes take effect immediately.

• Static initialization parameters cannot be changed for the current instance. You must change these parameters in the text initialization file or server parameter file and then restart the database before changes take effect.

ALTER SYSTEM SET SEC_MAX_FAILED_LOGIN_ATTEMPTS=3
                 COMMENT='Reduce from 10 for tighter security.'
                 SCOPE=SPFILE;

ALTER SYSTEM 
     SET LOG_ARCHIVE_DEST_4='LOCATION=/u02/oracle/rbdb1/',MANDATORY,'REOPEN=2'
         COMMENT='Add new destimation on Nov 29'
         SCOPE=SPFILE;

Clearing Initialization Parameter Values

You can use the ALTER SYSTEM RESET command to clear (remove) the setting of any initialization parameter in the SPFILE that was used to start the instance. Neither SCOPE=MEMORY nor SCOPE=BOTH are allowed. The SCOPE = SPFILE clause is not required, but can be included.

You may want to clear a parameter in the SPFILE so that upon the next database startup a default value is used.

Exporting the Server Parameter File

You can use the CREATE PFILE statement to export a server parameter file (SPFILE) to a text initialization parameter file. Doing so might be necessary for several reasons:

• For diagnostic purposes, listing all of the parameter values currently used by an instance. This is analogous to the SQL*Plus SHOW PARAMETERS command or selecting from the V$PARAMETER or V$PARAMETER2 views.

• To modify the &spfile;server parameter file by first exporting it, editing the resulting text file, and then re-creating it using the CREATE SPFILE statement

The exported file can also be used to start up an instance using the PFILE clause.

You must have the SYSDBA or the SYSOPER system privilege to execute the CREATE PFILE statement. The exported file is created on the database server machine. It contains any comments associated with the parameter in the same line as the parameter setting.

The following example creates a text initialization parameter file from the SPFILE:

CREATE PFILE FROM SPFILE;

Because no names were specified for the files, the database creates an initialization parameter file with a platform-specific name, and it is created from the platform-specific default server parameter file.

The following example creates a text initialization parameter file from a server parameter file, but in this example the names of the files are specified:

CREATE PFILE='/u01/oracle/dbs/test_init.ora'
       FROM SPFILE='/u01/oracle/dbs/test_spfile.ora';

CREATE PFILE='/u01/oracle/dbs/test_init.ora' FROM MEMORY;

Backing Up the Server Parameter File

You can create a backup of your server parameter file (SPFILE) by exporting it, as described in "Exporting the Server Parameter File". If the backup and recovery strategy for your database is implemented using Recovery Manager (RMAN), then you can use RMAN to create a backup of the SPFILE. The SPFILE is backed up automatically by RMAN when you back up your database, but RMAN also enables you to specifically create a backup of the currently active SPFILE.

Recovering a Lost or Damaged Server Parameter File

If your server parameter file (SPFILE) becomes lost or corrupted, the current instance may fail, or the next attempt at starting the database instance may fail. There are a number of ways to recover the SPFILE:

• If the instance is running, issue the following command to recreate the SPFILE from the current values of initialization parameters in memory:

  CREATE SPFILE FROM MEMORY;
  

  This command creates the SPFILE with the default name and in the default location. You can also create the SPFILE with a new name or in a specified location. See "Creating a Server Parameter File" for examples.

• If you have a valid text initialization parameter file (PFILE), recreate the SPFILE from the PFILE with the following command:

  CREATE SPFILE FROM PFILE;
  

  This command assumes that the PFILE is in the default location and has the default name. See "Creating a Server Parameter File" for the command syntax to use when the PFILE is not in the default location or has a non-default name.

• Restore the SPFILE from backup.

  See "Backing Up the Server Parameter File" for more information.

• If none of the previous methods are possible in your situation, perform these steps:

  1. Create a text initialization parameter file (PFILE) from the parameter value listings in the alert log.

     When an instance starts up, the initialization parameters used for startup are written to the alert log. You can copy and paste this section from the text version of the alert log (without XML tags) into a new PFILE.

     See "Viewing the Alert Log" for more information.

  2. Create the SPFILE from the PFILE.

     See "Creating a Server Parameter File" for instructions.

Read/Write Errors During a Parameter Update

If an error occurs while reading or writing the server parameter file during a parameter update, the error is reported in the alert log and all subsequent parameter updates to the server parameter file are ignored. At this point, you can take one of the following actions:

• Shut down the instance, recover the server parameter file and described earlier in this section, and then restart the instance.

• Continue to run the database if you do not care that subsequent parameter updates will not be persistent.

Viewing Parameter Settings

You can view parameter settings in several ways, as shown in the following table.