Abstract: A tape library system for handling multi-volume tapes includes an automated tape system with at least one tape unit and a robotic tape handling system. The tape library system receives requests from at least one host for access to a specified tape volume in a specified tape unit. The tape library system includes a tape/library control unit that receives the request from the host computer and maps the specified tape volume to a tape cartridge. The TLCU determines if the tape cartridge is currently loaded in a tape unit and, if the tape cartridge is not loaded, commands the robotic tape handling system to load the cartridge into an available unit. The TLCU forms a virtual path between the host computer and the loaded tape unit. Data is then transferred between the loaded tape unit and the host computer. Thus, the host computer is presented with a virtual view of connection to the specified tape volume loaded in the specified tape unit.

Abstract: Tape drives and methods for reading/writing on first and second surfaces of a tape include a pair of read/write heads for reading/writing on the surfaces at the same time in synchronism as the tape moves across the heads. A controller determines if the heads are reading corresponding portions of the surfaces of the tape at the same time. The controller also determines if the heads are moving to corresponding portions of the surfaces of the tape in the same time period. The controller further determines if the heads are moving to corresponding tracks on the surfaces of the tape at the same time.

Abstract: A tape threading arm mechanical linkage undergoes significant variations in mechanical advantage through its motion. In order to compensate for the drastic changes in the mechanical advantage of the tape threading arm, the operation of the tape threading arm is divided up into a plurality of control segments. Each segment represents a portion of the tape threading path wherein the mechanical advantage of the tape threading arm remains fairly constant. A control memory stores data indicative of various control parameters that are required to regulate the operation of the tape threading arm motor to maintain the tape speed throughout this segment of the tape threading path at a constant velocity. In addition, the measured velocity of the magnetic tape as it is removed from the file reel is used to compute the difference between the predicted operation of the tape threading arm and the measured operation of the tape threading arm.