Archivelog mode is a special mode of database operation that requires a copy to be made of each redo log file before it can be reused. If you want to recover all changes to your database in the event of a loss, you need to run your database in archivelog mode and you need to archive your log files.
To place a database into archivelog mode, follow these steps:
- Shut down the database.
- Back up the database.
- Mount the database (using the
STARTUP MOUNT
command).
- Issue the
ALTER DATABASE ARCHIVE LOG
command to enable archivelog mode.
- Open the database (using the
ALTER DATABASE OPEN
command).
The commands listed in the above steps should be issued from SQL * Plus.
If you are using Oracle's Enterprise Manager software, you have the option of using Instance Manager for steps 3-5. The following simulation shows you how:
It is not necessary to use Instance Manager to enable ARCHIVELOG mode in Oracle 23c.
In modern Oracle versions like Oracle 23c, enabling ARCHIVELOG mode is typically done via SQL\*Plus or any DBA tool with SQL access, such as SQL Developer, RMAN, or Cloud Control (OEM). The Instance Manager, which was part of older GUI tools (like Oracle Enterprise Manager Database Control in earlier releases), has largely been phased out or replaced by more powerful tools, such as Oracle Cloud Control and DBCLI/OCI CLI.
✅ Recommended Way to Enable ARCHIVELOG Mode in Oracle 23c:
-- Connect as SYSDBA
SHUTDOWN IMMEDIATE;
STARTUP MOUNT;
ALTER DATABASE ARCHIVELOG;
ALTER DATABASE OPEN;
You can verify it using:
ARCHIVE LOG LIST;
If using Oracle Cloud (OCI):
- You can use the OCI Console or DBCLI to toggle archive log mode on Autonomous or DBCS environments.
- For Autonomous Database, ARCHIVELOG mode is not configurable, as Oracle handles it internally.
Summary:
- ❌ Instance Manager is obsolete and not needed.
- ✅ Use SQL*Plus, RMAN, or Cloud tools to configure ARCHIVELOG mode in Oracle 23c.
It is important to understand that placing a database into archivelog mode ensures that Oracle will not overwrite a redo log file until it has been copied to the archive log destination. Once you place a database into archivelog mode, you have to choose between either manually archiving your redo logs or having Oracle do that for you. You'll learn how to make that choice later in this module.
In the next lesson, you will specify the directory to which Oracle archives log files.