Storage Technology Corporation

Exabyte Corporation

Ecrix Corporation

Kelly J Beavers

Michael E Moy

Frank A Goodknight

Frederick G Munro

Thomas J Studebaker

Paul Kummli

Stuart W Bray

Richard G Sellke

Raymond L Lucchesi

Eugene Kutasy

Michael A Blatchley

Thomas Edward Zaczek

David L Detro

Steven P Georgis

Steven F Nugent

Ronald W Korngiebel

Christopher L Turner

James R Baer

Timothy C Hughes

John L Seabury

Steve E Haugland

Christopher J Turner

A method and apparatus for varying track recording speed to maximize host-to-tape data transfer rates is presented. Variable data transfer rates of host systems and networks are accommodated by continually adjusting the tape speed to match the tape drive to the host's actual transfer rate. The speed of the tape is adjusted according to both the level of data present in the tape drive data buffer and whether the current mode of the drive is write mode or read mode. In the preferred embodiment, when the tape speed is accelerated or decelerated while writing a number of data track pairs to tape, a predetermined number of dummy track pairs are first written to tape at the current speed. On the next write head phase after the speed is increased or decreased as appropriate while the read heads are over the track, a predetermined number of dummy track pairs followed by more data track pairs are written to the tape at the new speed.

Variable speed recording method and apparatus for a magnetic tape drive

This data security arrangement provides a significant level of data security in an automatic magnetic tape cartridge library by isolating the actual data from the control of the data retrieval process. This isolation is accomplished by the use of a plurality of architectural devices that dissociate control and data. The data written on the magnetic tape cartridges cannot be accessed by the library modules. The library modules are not electrically connected to the tape drives or the data bus that connects the tape drives to the host computer. In addition, library software on the host computer emulates an operator's console and intercepts all tape mount commands generated by the host computer. The library software translates these commands into control signals to activate the library module to retrieve a designated magnetic tape cartridge and load this cartridge into a tape drive. Thus, the data retrieval apparatus is separate from the library control apparatus. The library module is unaware of the identity of the data stored on the magnetic tape cartridges and the host computer is unaware of the existence of the automated magnetic tape cartridge library.

Data security arrangement for an automated magnetic tape cartridge

A storage and retrieval subsystem in a data processing system includes a plurality of magnetic tape cartridges, a host computer, and a library storage module storing the plurality of magnetic tape cartridges in substantially upright positions. The library storage module includes a first cylindrical array of storage cells centered about a vertical axis, a second cylindrical array concentrically arranged about the first array, and a library tape unit including a plurality of tape drives, each of the tape drives being adapted to receive one of the magnetic tape cartridges in a substantially horizontal transducing position. A robot within the library storage module is used to transfer selected ones of the magnetic tape cartridges between their substantially upright positions and the substantially horizontal transducing positions at a selected tape drive. A first controller outboard the channel communicating with the host computer is adapted to receive commands from the host computer for interfacing between the host computer and the library storage module, and a second controller inboard of the channel is adapted to receive commands from the outboard controller for interfacing between the outboard controller and the robot.

Automated cartridge system

A storage and retrieval subsystem in a data processing system includes a plurality or magnetic tape cartridges, a host computer, and a library storage module storing the plurality of magnetic tape cartridges in substantially upright positions. The library storage module includes a first cylindrical array of storage cells centered about a vertical axis, a second cylindrical array concentrically arranged about the first array, and a library tape unit including a plurality of tape drives, each of the tape drives being adapted to receive one of the magnetic tape cartridges in a substantially horizontal transducing position. A robot within the library storage module is used to transfer selected ones of the magnetic tape cartridges between their substantially upright positions and the substantially horizontal transducing positions at a selected tape drive. A first controller outboard the channel communicating with the host computer is adapted to receive commands from the host computer for interfacing between the host computer and the library storage module, and a second controller inboard of the channel is adapted to receive commands from the outboard controller for interfacing between the outboard controller and the robot.

A tracking system and method are disclosed for a helical-scan recording device to automatically maintain the recording/playback heads in alignment with the stripes of recorded information on the magnetic tape. Each stripe on the magnetic tape includes a servo area having four distinct zones. An analog servo signal at a preselected frequency is recorded on one of the four zones on each stripe and is recorded at different ones of the four zones in succession on each group of four adjacent stripes. The servo signal recorded on the stripes is detected during playback and processed to maintain the desired head positioning relative to the stripes on the tape. The servo head is preferably maintained between adjacent stripes on the magnetic tape and signals detected from each of the adjacent stripes maintain head alignment by shifting the positioning of the head in either direction as needed.

Cyclical servo zone tracking method and apparatus for helical scan

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Boulder, CO, United States of America

Kelly J Beavers