About previewing volume configuration changes
Use this option to preview the changes before you update the EMM database. This option lets ensure that all new media have barcodes before you add them to the EMM database.
Note:
If you preview the configuration changes first and then update the EMM database, the update results may not match the results of the preview operation. Possible causes may be the changes that occur between the preview and the update. Changes can be to the state of the robot, to the EMM database, to the barcode rules, and so on.
See Updating the NetBackup volume configuration with a robot's contents.