International Business Machines Corporation

Ronald K Rhodes

Alex Chliwnyj

Steven Ross Bentley

Steven Douglas Johnson

Sushama M Paranjape

James Francis Crossland

Colleen Renee Stouffer

Wayne T Comeaux

Robert C Baca

Accurate tape servo track following is achieved by sampling servo edges at tape head alignments established with non-servo information, and processing the samples to (1) estimate optimal tape head index positioning to best align data as well as servo components, and (2) provide corrected position error signals (PESs) including a calculated error for comparison during ongoing servo track following to maintain the tape head at an optimal alignment for accurate alignment with the servo edges as well as data tracks on the tape.

Servo edge correction using edge samples taken by independently

The present invention provides an apparatus and method for initializing a magnetic tape when it is mounted in a tape drive. In one embodiment, each time a tape is mounted, control parameters pertaining to the servo system are set to predetermined values and servo read elements in the tape head are activated. The tape is moved and a number of position error signal (PES) samples are read and averaged for each of the active servo elements. The value of one or more of the parameters is modified and new PES readings and averages are obtained. This process is repeated for a predetermined combination of parameter values whereupon read and write offsets are calculated and stored for each servo element. During an actual read (or write) operation, the tape head is positioned relative to the data tracks on which the desired data is located and servo control enabled. An actual PES generated by each active servo element is adjusted by the read (or write) offset calculated for that servo element, thereby substantially canceling the effects of element-to-element, module-to-module and azimuthal deviations. The resulting adjusted PES is used by the servo controller to optimize track following.

Initialization and calibration of magnetic tape having multiple servo

A method and apparatus for accurately locating targeted append points in a tape drive. The effects of interlayer slip (ILS) are eliminated and smaller IBGs are possible thus providing increased data capacity for a given tape cartridge. A coarse tachometer count is used in combination with the read dataflow to accurately locate the proper append point even with a small IBG size. The appended data are assured to be written using the proper tape velocity which virtually eliminates improper write appends and read temporary errors previously caused by ILS effects. The solution also guarantees that customer data previously written to the tape are not accidentally overwritten.

Method and apparatus for improving inter-block gap length tolerance and

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Tucson, AZ, United States of America

Ronald K Rhodes