Lesson 1

The basic concepts of (RMAN) Recovery Manager and how to create a recovery catalog were previously discussed.
This lesson will discuss the commands you will encounter when performing basic maintenance on your recovery catalog. Furthermore, you will learn how to start Recovery Manager 1) with and 2) without a recovery catalog and basic maintenance commands that you can use on the recovery catalog. In the module, you will learn to:

1. Issue the command to start RMAN
2. Demonstrate how to start RMAN without a recovery catalog
3. Register a target database into your recovery catalog
4. Discuss the use of the reset command
5. Demonstrate how to resynchronize a target database using the resynch command
6. Identify other situations where the resynch command is needed
7. Use the change command to alter the information in your recovery catalog
8. Use the delete command to remove data from your recovery catalog and the validate command to check the validity of your recovery catalog

You will find that the information presented in this module will be used infrequently. Some commands will be executed once or twice, while others not at all. You need to know this information for those infrequent times, and you will be tested on this information during the database administrator Oracle certification exams. In the next lesson, you will learn about starting RMAN with a recovery catalog.

To start RMAN (Recovery Manager) in Oracle 23c, follow these steps:

1. Open a terminal (Linux/Unix) or command prompt (Windows).
2. Set the Oracle environment variables if you haven't already:
   • On Linux/Unix, execute:

             . oraenv
             

   • On Windows, make sure the Oracle environment variables (like ORACLE_HOME and PATH) are correctly set.
3. Start RMAN by issuing the following command:

       rman target /
       

The `target /` connects RMAN to the target database (the database you want to back up or recover). The `/` indicates that you're using OS authentication to connect.
If you want to connect to a remote Oracle 23c instance or use a specific username and password, you can use this command:

rman target username/password@tns_alias

Replace `username`, `password`, and `tns_alias` with the actual credentials and TNS (Transparent Network Substrate) alias of the target database. Once connected, you'll be in the RMAN prompt, where you can issue backup or recovery commands.

Use of the recovery catalog involves some additional maintenance activities, which include upgrading the catalog during a database upgrade or migration, manually resetting the database incarnation, and resynchronizing the recovery catalog after certain database operations. This section describes those activities, as well as other maintenance considerations, including removing a database from the recovery catalog and using the Oracle EXP/IMP utilities to back up the recovery catalog. Finally, this section reviews the different recovery catalog views and what they are used for. |

• Unregistering a Database in RMAN
  Prior to Oracle Database 10g, unregistering a database from the recovery catalog was a manual process. Now, Oracle makes removing a database from the recovery catalog as easy as issuing the command unregister database. Here is an example:
  

  RMAN> Unregister database mydb;
  

  When this command is executed, the metadata for the database in the recovery catalog is removed completely. Also, any metadata older than CONTROL_FILE_RECORD_KEEP time is removed from the control file. All local scripts for that database will also be removed from the recovery catalog.