Simplified storage media library subsystem

Abstract

The present invention discloses a storage library subsystem which utilizes robotic arm mechanisms to move storage media cartridges between inventory storage locations and read/write devices. This library subsystem simplifies the motion required of the robotic arms to reduce the complexity of the robotic mechanisms and thereby reduce the complexity, size and cost of the library subsystem. One factor in simplifying the robotic motion is the use of higher density storage media cartridges. Higher density cartridges enables a corresponding reduction in the total number of media cartridges inventoried and the total range of motion required of the robotic arm. Another factor in simplifying the robotic motion is the placement of media cartridges in vertically aligned columns around the circumference of a rotating cylindrical carousel. The carousel may be rotated to vertically align a column of storage media cartridges with a read/write device below in the same vertical plane. This configuration permits the robotic arm to access both the storage media cartridges and the read/write devices without the need for rotational movement. Another simplification of the subsystem is realized by limiting human access to the internal inventory of the library. The inventory may be accessed by a human operator during normal operation only by library controlled access through a Cartridge Access Port (CAP). Only certain reserved positions on the rotating carousel will be available at the CAP when the library unlocks the door covering the CAP. By limiting human operator access to the library inventory the present invention eliminates the need for complex components such as vision systems to update library inventory following human intervention. Alternative exemplary embodiments restore some limited rotational movement to the robotic arm to enable a single arm to service multiple carousels or read/write/drives.