Before opening the door to change tapes in a,NetVault Backup (NVBU) controlled library, you must issue the Open Door command from the NVBU Device Management window. NVBU attempts to put a software lock on the library door which prevents anyone from opening the door without issuing the Open Door command. Moreover, if you do not issue this command, then NVBU will not know when tapes are added, removed or rearranged, and may attempt to load non-existent media.
To open a library door from the NVBU Console
1. On the Devices tab, right-click the library and select Open Door. The library goes offline when you open the door
2. To bring it back online, right-click, and select Door Closed.