Enabling the Creation and Use of Oracle-Managed Files

The following initialization parameters allow the database server to use the Oracle-managed files feature:

Initialization Parameter	Description
`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. Also used as the default file system directory for redo log and control files if `DB_CREATE_ONLINE_LOG_DEST_n` is not specified.
`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.
`DB_RECOVERY_FILE_DEST`	Defines the location of the flash recovery area, which is 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.

The file system directory specified by either of these parameters must already exist: the database does not create it. The directory must also have permissions to allow the database to create the files in it.

The default location is used whenever a location is not explicitly specified for the operation creating the file. The database creates the filename, and a file thus created is an Oracle-managed file.

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

Setting the DB_CREATE_FILE_DEST Initialization Parameter

Include the DB_CREATE_FILE_DEST initialization parameter in your initialization parameter file to identify the default location for the database server to create:

Datafiles
Tempfiles
Redo log files
Control files
Block change tracking files

You specify the name of a file system directory that becomes the default location for the creation of the operating system files for these entities. The following example sets /u01/oradata as the default directory to use when creating Oracle-managed files:

DB_CREATE_FILE_DEST = '/u01/oradata'

Setting the DB_RECOVERY_FILE_DEST Parameter

Include the DB_RECOVERY_FILE_DEST and DB_RECOVERY_FILE_DEST_SIZE parameters in your initialization parameter file to identify the default location in which Oracle Database should create:

Redo log files
Control files
RMAN backups (datafile copies, control file copies, backup pieces, control file autobackups)
Archived logs
Flashback logs

You specify the name of file system directory that becomes the default location for creation of the operating system files for these entities. For example:

DB_RECOVERY_FILE_DEST      = '/u01/oradata'
DB_RECOVERY_FILE_DEST_SIZE = 20G

Setting the DB_CREATE_ONLINE_LOG_DEST_n Initialization Parameter

Include the DB_CREATE_ONLINE_LOG_DEST_n initialization parameter in your initialization parameter file to identify the default location for the database server to create:

Redo log files
Control files

You specify the name of a file system directory that becomes the default location for the creation of the operating system files for these entities. You can specify up to five multiplexed locations.

For the creation of redo log files and control files only, this parameter overrides any default location specified in the DB_CREATE_FILE_DEST and DB_RECOVERY_FILE_DEST initialization parameters. If you do not specify a DB_CREATE_FILE_DEST parameter, but you do specify the DB_CREATE_ONLINE_LOG_DEST_n parameter, then only redo log files and control files can be created as Oracle-managed files.

It is recommended that you specify at least two parameters. For example:

DB_CREATE_ONLINE_LOG_DEST_1 = '/u02/oradata'
DB_CREATE_ONLINE_LOG_DEST_2 = '/u03/oradata'

This allows multiplexing, which provides greater fault-tolerance for the redo log and control file if one of the destinations fails.