A library apparatus for storage media such as optical disks includes a rotatable cell drum 18 having several columns of cells for the storage media, a load/unload device 22 for inserting and removing cartridges 16 one at a time, at least one drive 36 for reading from or writing to selected media, and an accessor 30 which moves the storage media 16 between the load/unload device 22 and the cell drum 18, and between the cell drum 18 and the drive 36. The load/unload device 22 rotates in a collinear arrangement with the cell drum 18, and can rotate in unison with the cell drum 18, or independently. The collinear arrangement of the cell drum and the load/unload device reduces the overall size of the library.
A direct entry/exit (DEE) door 721 exposes several cells in the cell drum 18 when the door is open. The DEE door is provided so that several storage media 730A can be placed in or removed from the cell drum at once, either manually or automatically. The library apparatus automatically rearranges the storage media to fill the cells nearest the drive 36, which reduces the time required to locate storage media in the cell drum and place them in the drive 36. A locking mechanism locks the DEE door when the cell drum rotates, and locks the cell drum when the DEE door is open. Each cell in the cell drum has a skew mounting preventing mechanism and inverse mounting preventing mechanism which prevent incorrect mounting of a cartridge in the cell drum.