What are Oracle-Managed Files (OMF)?

What are Oracle-Managed Files (OMF)?

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An Oracle database contains three types of physical files: data files, redo log files, and control files. When creating an Oracle database, names and locations of control files need to be specified in the database's initialization parameter file. Also, the names and locations of data files and redo log files need to be specified in the CREATE DATABASE statement. One of the problems with so created data files and redo log files is that when logical database structures (such as tablespaces and redo log groups) containing these files are dropped from the database, Oracle does not automatically remove these files from the hard disk. Therefore, they need to be manually deleted. Using Oracle-Managed Files can resolve the issue, as Oracle automatically deletes these files when the associated logical database structures are dropped.

Two new initialization parameters named DB_CREATE_ONLINE_LOG_DEST_n and DB_CREATE_FILE_DEST are introduced in Oracle9i, which are used to implement Oracle-Managed Files. Specifying these parameters in a database's initialization parameter file eliminates the need of explicitly specifying names and locations of physical files when creating the database.

The DB_CREATE_ONLINE_LOG_DEST_n parameter specifies the default location where Oracle creates redo log files and control files. The DB_CREATE_FILE_DEST parameter specifies the default location where Oracle creates data files. It also specifies the default location for redo log files and control files if the DB_CREATE_ONLINE_LOG_DEST_n parameter is not specified in the initialization parameter file. Oracle automatically names these files.

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