If you need to back up specific databases, you can do that by creating a user-defined subclient.
From the navigation pane, go to Protect > Applications > Exchange.
The Exchange page appears.
Click an Exchange database.
The Exchange Database page appears.
Click Add Subclient.
The Add subclient wizard appears.
On the General page, type a name for the subclient, select a plan, and then click Next.
On the Settings page, type or select the maximum number of streams that is required for running a backup operation.
By default, the number of streams is 2.
Optional: If you want block-level backup operations to use the backed-up databases for live browse, select the Optimize for message level recovery check box.
You can also enable block-level backups later. For more information, see Enabling Block-Level Backups for Exchange Databases.
On the Subclient content page, select the databases that you want to add to the user-defined subclient, and then click Next.
On the Server details page, specify whether to select the backup source manually or automatically:
To manually select the backup source, select Manual selection, and then, for each database, select the server that you want to use as the backup source.
To have the software automatically select the backup source, complete the following steps:
Select Automatic selection.
To use a passive server, select the Backup from passive copy check box.
To use the active server when no passive server is available, select the Backup from active copy if no passive copy is available check box.
To run backup operations on the server that is least likely to become active in a failover case, select the Use last activation preference to select passive copy check box.
For more information, see Configuring Manual or Automatic Selection of the Backup Source.
The user-defined subclient appears on the Exchange Database page, under Subclients.