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Abstract

An optical disk system emulating a 3480 magnetic tape subsystem having one or more magnetic tape drives, includes a VMEGate channel attached processor for receiving CCW tape commands, a SCSI board for controlling SCSI optical disk drives, a serial I/O board for controlling jukebox optical disk media handlers for automatically robotically loading and unloading optical disks containing virtual tape data into the optical disk drives, a cache RAM for buffering data between the channel and the optical disk drives, operator consoles for emulating the 3480 magnetic tape subsystem control panels, an SBC computer and VME bus for central control of the system, and floppy and hard disk drives for storing emulation SBC programs and disk directories, to enable the system to exhibit an organization of virtual tape data into a system of pointers and user records of the virtual tapes, a reallocatable mapping between magnetic tape drives and the optical disk drives, disk directories cross referencing virtual tapes VSNs to optical disks for locating particular optical disks storing requested VSNs, and to enable WORM optical media to appear to the channel as rewritable magnetic tape through the conversion of tape commands to jukebox load operations and optical disk drive seek operations for increased performance, said system emulates a 3480 magnetic tape subsystem by using jukeboxes to automatically load optical media into and out of optical disk drives and by using a dynamic re-allocation method for maintaining a one-to-one mapping between the virtual magnetic tape drives and the optical disk drives, which reduces access speed to the data.

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First Claim