http://www.virt-infrastructure.com/?p=110 shows the setup of QUADStor virtual tape library (VTL) with NetBackup 7.5.x. The article also describes the setup using QUADStor storage virtualization for data deduplication. While the article does not go into the details, the screenshots illustrates most of the necessary steps such as creating virtual disks, using virtual disks as storage for virtual tape cartridges, accessing the virtual devices from NetBackup and performing backups.