0 Oracle Management Files (OMF)

Oracle Management Files is the feature allow oracle instance manage the database file, such as the tablespace file. It can name the files base on the OFA rule in the predefine location and delete the file when the file is no longer require in the even such as drop tablespace. It is new feature available after Oracle 9i.

DB_CREATE_FILE_DEST	Require	Data File, Temporary File, Block Change Tracking File. When no DB_CREATE_ONLINE_LOG_DEST, it can be use by control file and log file
DB_CREATE_ONLINE_LOG_DEST_n(1~5)	Optional	Control File, Log File.
DB_RECOVERY_FILE_DEST	Optional	Default location for Archive log and RMAN backup files

When DB_CREATE_FILE_DEST is not set, the OMF is not enable.

-- If no db_create_file_dest is set, the OMF is not enable

show parameter db_create

show parameter db_recovery

Enable the OMF

-- If OMF is not enable, below "create tablespace" would fail

Create tablespace mytbs;

alter system set db_create_file_dest='/home/oracle/app/oracle/oradata/orcl';

-- Re create the tablespace

Create tablespace mytbs;

-- Query the tablespace

col tablespace_name format a21

col "FILE_NAME" format a20

select DT.TABLESPACE_NAME,DT.contents,DT.STATUS,DT.SEGMENT_SPACE_MANAGEMENT, DT2.FILE_NAME,DT2.BYTES

from DBA_TABLESPACES DT, DBA_DATA_FILES  DT2

where DT.TABLESPACE_NAME= DT2.TABLESPACE_NAME and DT.TABLESPACE_NAME='MYTBS';

-- drop tablespace

drop tablespace MYTBS;

 

Reference

http://docs.oracle.com/cd/B10501_01/server.920/a96521/omf.htm