You must manually add a DB2 MultiNode database to an instance to back up that database.
From the navigation pane, go to Protect > Databases.
The Instances page appears.
Click the instance.
The instance page appears.
In the Databases section, on the right area of the page, click Add database.
The Add DB2 database dialog appears.
In the Database name box, enter a name for the database.
You must enter the name of a database which already exists on the client.
From the Plan list, select the server plan to use for the database.
By default, the system selects the server plan that was already configured at the instance level. If you select a different server plan for this database, the system uses the newly-selected server plan for this database. The server plan is also used for log backups.
The system creates a default data subclient and a default log subclient. You can create additional subclients for tablespaces that frequently change or have a different backup schedule than the entire database. For more information, see Adding a DB2 MultiNode Subclient.