Oracle SPFILE and PFILE

Oracle provides two different parameter files, PFILE and SPFILE.

PFILE is a text based file and in order to add/modify any database parameters, need to edit the INIT.ORA file using “vi” in unix or notepad in windows. To apply new or modified database parameters changes, database restart is required.

SPFILE is a binary file and introduced in Oracle 9i. SPFILE simplifies administration, maintaining parameter settings consistent and Server parameter file is a binary file let you make persistent changes to individual parameters. Use the CREATE SPFILE statement to create a Server Parameter file from PFILE with SYSDBA/SYSOPER privilege.

By default PFILE or SPFILE default location is “$ORACLE_HOME/dbs” for UNIX and LINUX, %ORACLE_HOME%\database for Windows. In case of RAC, SPFILE located on the shared storage.

You can change the SPFILE parameters using Enterprise manager or ALTER SYSTEM SET ‘parameter’ statement with SCOPE clause. The SCOPE clause has three values MEMORY, SPFILE and BOTH.

SPFILE: The change is applied in the server parameter file only and is effective at the next startup.
For Ex: - SQL> ALTER SYSTEM SET SGA_MAX_SIZE=1024m SCOPE=spfile;

Memory: The change is applied in memory only and the effect is immediate.
For Ex:- SQL> ALTER SYSTEM SET JOB_QUEUE_PROCESSES=50 SCOPE=MEMORY;

BOTH: The change is applied in both the server parameter file and memory. For dynamic parameters the effect is immediate.
Ex: - SQL> ALTER SYSTEM SET SGA_TARGET=1024m SCOPE=BOTH;

For Static parameters the MEMROY, BOTH specifications are not allowed. Only SPFILE is allowed.

If you do not specify the SCOPE clause then the default is BOTH. For Dynamic parameters you can specify DEFERRED keyword and the specified change is effective only for future sessions.

During Database startup Oracle searches for initialization parameter file under $ORACLE_HOME/dbs in UNIX and $ORACLE_HOME/database on Windows in following order.

spfileSID.ora
spfile.ora
initSID.ora
init.ora

Backup/Restore parameter files(SPFILE and PFILE):
Using Recovery Manager(RMAN), SPFILE can be backed up with database control file by setting
RMAN> CONFIGURE CONTROLFILE AUTOBACKUP ON;
SPFILE can be restored using following RMAN command.
RMAN> RESTORE CONTROLFILE FROM AUTOBACKUP;

PFILE cannot be backed-up using RMAN, backup and restore can be done using O/S copy command.

Common Errors and solutions in modifying SPFILE:
1. SQL>alter system SET LOG_ARCHIVE_DEST='/oradata/TESTDB' scope=both;
alter system SET LOG_ARCHIVE_DEST='/oradata/ TESTDB' scope=both
*
ERROR at line 1:
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-16018: cannot use LOG_ARCHIVE_DEST with LOG_ARCHIVE_DEST_n or
DB_RECOVERY_FILE_DEST

Solution: OCATION keyword is required.
SQL> alter system set log_archive_dest_1='location=/oradata/ TESTDB' scope=both;
System altered.

2. SQL> alter system set log_archive_dest_1='location=/oradta/ TESTDB' scope=both;
alter system set log_archive_dest_1='location=/oradata/ TESTDB' scope=both
*
ERROR at line 1:
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-16032: parameter LOG_ARCHIVE_DEST_1 destination string cannot be translated
ORA-07286: sksagdi: cannot obtain device information.
Linux-x86_64 Error: 2: No such file or directory

Solution: LOG_ARCHIVE_DEST_1 is incorrect or does not exist. Prove correct path.

Regards,
Satishbabu Gunukula
http://www.oracleracexpert.com