Setting Initial Database ArchiveLog Mode

You set the initial archiving mode as part of database creation in the CREATE DATABASE statement. Usually, you can use the default of NOARCHIVELOG mode at database creation because there is no need to archive the redo information generated by that process. After creating the database, decide whether to change the initial archiving mode. If you specify ARCHIVELOG mode, you must have initialization parameters set that specify the destinations for the archive log files

Changing the Database Archiving Mode

To change the archiving mode of the database, use the ALTER DATABASE statement with the ARCHIVELOG or NOARCHIVELOG clause. To change the archiving mode, you must be connected to the database with administrator privileges (AS SYSDBA).

The following steps switch the database archiving mode from NOARCHIVELOG to ARCHIVELOG:

1) Shut down the database instance

SHUTDOWN

An open database must first be closed and any associated instances shut down before you can switch the database archiving mode. You cannot change the mode from ARCHIVELOG to NOARCHIVELOG if any datafiles need media recovery.

2) Back up the database.

Before making any major change to a database, always back up the database to protect against any problems. This will be your final backup of the database in NOARCHIVELOG mode and can be used if something goes wrong during the change to ARCHIVELOG mode

3) Edit the initialization parameter file to include the initialization parameters that specify the destinations for the archive log files

4) Start a new instance and mount, but do not open, the database.

STARTUP MOUNT

To enable or disable archiving, the database must be mounted but not open.

5) Change the database archiving mode. Then open the database for normal operations.

ALTER DATABASE ARCHIVELOG;

ALTER DATABASE OPEN;

6) Shut down the database.

SHUTDOWN IMMEDIATE

7) Back up the database.

Changing the database archiving mode updates the control file. After changing the database archiving mode, you must back up all of your database files and control file. Any previous backup is no longer usable because it was taken in NOARCHIVELOG mode.