how do you convert a non Oracle Managed files into an Oracle Managed file
The following parameters enable the Oracle to use OMF(Oracle Managed File).
DB_CREATE_FILE_DEST- For Datafiles
DB_CREATE_ONLINE_LOG_DEST_n- For redo log files.
DB_RECOVERY_FILE_DEST- For controlfiles.

To convert non-OMF datafiles to OMF-

1) Set the db_create_file_dest parameter.

alter system set db_Create_file_dest='+DATA';


2) select file#, name from v$datafile;--to list all the datafiles and their file number.

3) alter database move datafile 1; --repeat this for all datafiles.

To convert non-OMF redo log files to OMF

1) set the DB_CREATE_ONLINE_LOG_DEST_n

2) Create new OMF redo log files.

 alter database add LOGFILE group 5 size 100M;


3) Drop the old redo log files.