Call now: 252-767-6166  
Oracle Training Oracle Support Development Oracle Apps

 E-mail Us
 Oracle Articles
New Oracle Articles

 Oracle Training
 Oracle Tips

 Oracle Forum
 Class Catalog

 Remote DBA
 Oracle Tuning
 Emergency 911
 RAC Support
 Apps Support
 Oracle Support

 SQL Tuning

 Oracle UNIX
 Oracle Linux
 Remote s
 Remote plans
 Application Server

 Oracle Forms
 Oracle Portal
 App Upgrades
 SQL Server
 Oracle Concepts
 Software Support

 Remote S


 Consulting Staff
 Consulting Prices
 Help Wanted!


 Oracle Posters
 Oracle Books

 Oracle Scripts

Don Burleson Blog 









Oracle Managed Files (OMF)

Oracle Tips by Burleson Consulting

Oracle Managed Files (OMF) directly manages file creation and deletion at the operating system level. Operations are specified in terms of database objects rather than filenames. Oracle internally uses standard file system interfaces to create and delete files as needed for the database structures such as tablespaces, online redo log files, and control files.

Administrators need to specify the file system directory to be used for a particular type of file. Thereafter, Oracle manages to create unique files when needed and also deletes files that are not needed. The advantages include:

* No need to bother about the file names and storage requirements. Oracle provides a unique file name.

* Eliminates the need for the DBA to directly manage OS files.

* Allows operations to be specified in terms of objects and not files.

* Reduces the chance of overwriting a file. Avoids accidental corruption of data files.

* Reduces wasted disk space consumed by obsolete files. When a tablespace is dropped, the relevant files are automatically removed at the host level.

The following initialization parameters specify the file location:

* db_create_file_dest: Defines the location of the default file system directory where Oracle creates data files or temp files when no file specification is given in the object creation statement.

* db_create_online_log_dest_n: Defines the location of the default file system directory for online redo log files and control files when no file specification is given in the creation statement. This initialization parameter can be used multiple times where n specifies a multiplexed copy of the online redo log or control file.

Note that the file system directory specified by either of these parameters must already exist. Oracle does not create it. The directory must also have permissions to allow Oracle to create the files in it. The default location is used whenever a location is not explicitly specified for the operation of creating a file. Oracle creates the filename, and a file thus created is an Oracle-managed file. The following example sets /u01/oracle/data/applic as the default directory to use when creating Oracle-managed files:

DB_CREATE_FILE_DEST = '/u01/oracle/data/applic'

By default, this location would be applicable for data files, temp files, Online redo log files, and control files. However, the db_create_online_log_dest_n initialization parameter can be included in the initialization parameter file to identify the default location for the database server to create online redoes log files and control files. For example:

DB_CREATE_ONLINE_LOG_DEST_1 = '/u03/oracle/redo/applic'
DB_CREATE_ONLINE_LOG_DEST_2 = '/u04/oracle/redo/applic'

Also, the DB_CREATE location can also be changed with the ALTER SYSTEM command.

For example, the following commands change the OMF directory location to '/u05/oracle/data/applic', and creates a new tablespace.

DB_CREATE_FILE_DEST = '/u05/oracle/data/applic' ; 

CREATE TABLESPACE tbs_1; # creates def.size of 100MB

For more details, refer to the chapter on Using Oracle Managed Files in the Oracle 10g Database Administrator's Guide.

With RAC systems, the OMF facility can only be used if the cluster system is using the cluster file system. The availability of the cluster file system with a set of mounted file systems, allows a directory to be set up for OMF files. The DBCA also supports Oracle Managed Files for operating systems that support a cluster file system.

Oracle Training from Don Burleson 

The best on site "Oracle training classes" are just a phone call away! You can get personalized Oracle training by Donald Burleson, right at your shop!

Oracle training



Oracle Training at Sea
oracle dba poster

Follow us on Twitter 
Oracle performance tuning software 
Oracle Linux poster


Burleson is the American Team

Note: This Oracle documentation was created as a support and Oracle training reference for use by our DBA performance tuning consulting professionals.  Feel free to ask questions on our Oracle forum.

Verify experience! Anyone considering using the services of an Oracle support expert should independently investigate their credentials and experience, and not rely on advertisements and self-proclaimed expertise. All legitimate Oracle experts publish their Oracle qualifications.

Errata?  Oracle technology is changing and we strive to update our BC Oracle support information.  If you find an error or have a suggestion for improving our content, we would appreciate your feedback.  Just  e-mail:  

and include the URL for the page.


Burleson Consulting

The Oracle of Database Support

Oracle Performance Tuning

Remote DBA Services


Copyright © 1996 -  2017

All rights reserved by Burleson

Oracle ® is the registered trademark of Oracle Corporation.

Remote Emergency Support provided by Conversational