A Backup server or storage node acts as a client of the silo management software. Backup communicates with the silo through the Silo Tape Library Interface (STLI) library.
To access the volumes and devices in a silo, Backup sends a request to the silo management software, in the form of an STLI library call. For example, to mount a volume in a silo device, the Backup daemon sends a request to the silo management software to mount the volume into a particular device in the silo. The silo server responds to the request and mounts the volume in the silo. For further details on this process, refer to the stli man page.
The silo management software controls many of the operations that Backup controls with an autochanger. For example, the silo management software keeps track of the slot where each silo volume resides and usually also controls the deposit and withdrawal of volumes and automated cleaning of silo devices.