This type of configuration is useful when the tape library is not directly attached to the NAS server. For example, you can use this configuration for the NAS module as this does not support LAN-free backup.
In the diagram, the storage management application (DMA) sends backup instructions to the NAS server which then sends a backup copy of the data from its storage to the server which is attached to the tape library. The data is then stored onto tapes in the tape library.