How to Create and Use OMF

OMF indicates Oracle Managed Files. With the use of Oracle-managed files the administration of an Oracle Database can be simplified. Oracle-managed files eliminate the need for you, the DBA, to directly manage the operating system files comprising an Oracle Database. You specify operations in terms of database objects rather than filenames.

Enable the Creation of OMFs
The following initialization parameters allow the database server to use the Oracle-managed files feature.

1)DB_CREATE_FILE_DEST: Defines the location of the default file system directory where the database creates datafiles or tempfiles when no file specification is given in the creation operation. It is also used as the default file system directory for redo log and control files if DB_CREATE_ONLINE_LOG_DEST_n is not specified.

2)DB_CREATE_ONLINE_LOG_DEST_n:Defines the location of the default file system directory for redo log files and control file creation when no file specification is given in the creation operation. You can use this initialization parameter multiple times, where n specifies a multiplexed copy of the redo log or control file. You can specify up to five multiplexed copies.

3)DB_RECOVERY_FILE_DEST:Defines the location of the default file system directory where the database creates RMAN backups when no format option is used, archived logs when no other local destination is configured, and flashback logs. Also used as the default file system directory for redo log and control files if DB_CREATE_ONLINE_LOG_DEST_n is not specified.

Both of these initialization parameters are dynamic, and can be set using the ALTER SYSTEM or ALTER SESSION statement.

An Example of using OMF :
1)Setting the parameter for the session:


SQL> alter session set db_create_file_dest='/oradata';
Session altered.


2)Create Tablespace using OMF:

SQL> create tablespace omf_tbs;
Tablespace created.

3)Check the data file Location:

SQL> select file_name from dba_data_files where tablespace_name='OMF_TBS';
FILE_NAME
--------------------------------------------------------------------------------
/oradata/ARJUT/datafile/o1_mf_omf_tbs_4049w4op_.dbf

Here ARJUT is the Database Name.

The dafault location for datafile is Your settings for parameter/Database Name/datafile/Unique Name.dbf