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Browse Prior Art Database

A Mistracking Detector for High Density Indexed Tape Head Reliability

IP.com Disclosure Number: IPCOM000104394D
Original Publication Date: 1993-Apr-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 96K

Publishing Venue

IBM

Related People

Gniewek, JJ: AUTHOR [+2]

Abstract

When writing with an indexed tape head, the possibility of tape misguiding is not generally known and we must rely on guiding repeatability to avoid erasing or overwriting adjacent track data. At high track densities, and increased number of head indexing positions, this dependency on guiding alone becomes an unacceptable approach. This note describes a novel method of establishing a positive on track signal to avoid overwriting adjacent data tracks without impacting system operation or requiring special pre-formatted tapes.

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A Mistracking Detector for High Density Indexed Tape Head Reliability

      When writing with an indexed tape head, the possibility of tape
misguiding is not generally known and we must rely on guiding
repeatability to avoid erasing or overwriting adjacent track data.
At high track densities, and increased number of head indexing
positions, this dependency on guiding alone becomes an unacceptable
approach.  This note describes a novel method of establishing a
positive on track signal to avoid overwriting adjacent data tracks
without impacting system operation or requiring special pre-formatted
tapes.

      The figure is a simplified HTI view of a high density
bi-directional interleaved tape head and its associated data track
locations.  The area marked data region will contain a large number
of data tracks recorded by read/write data elements 1 through N and
formed by head indexing.  Outside the data region, the tape contains
guardbands to the edge of the tape.  As shown in the figure, we have
introduced write devices Swf (Split write forward) and Swr (Split
write reverse), which are single coil writers with a slotted P2
poletip forming a combed write element.  Both of these devices will
write long wavelength tracks on tape as shown in the figure while in
the initial head position and writing in the forward direction.
Therefore, long wavelength forward and reverse tracks Swf and Swr are
simultaneously written.

      Swr is in the reading gap, however, it is positioned far from
the nearest reader RN.  Furthermore, if we write with a long
wavelength which is not harmonically related to the data patterns,
has very long rise times, and if we maximize the separation between
the Swr leads and the RN leads, we will expect very little additional
read while write noise from Swr during the initial forward data pass.

      When the tape is initially loaded into a drive we will record
D.C.  servo tracks which will be composed of a tone pattern written
on a small section of the tape by all the data writers.  If this is a
virgin tape, we will begin writing the data and simultaneously write
the long wavelength tracks.  In a second case, the first full file
pass may have only been partially written.  Here the head will be
aligned by using the D.C.  servo tracks aligned to the data readers
and we will find the end of the recorded data.  At this point we...