Browse Prior Art Database

Track Density Zoning

IP.com Disclosure Number: IPCOM000119458D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 1 page(s) / 61K

Publishing Venue

IBM

Related People

Hirko, RG: AUTHOR

Abstract

It is widely known that in high performance disk files the largest amount of pulse crowding or intersymbol interference (ISI) occurs at the smallest radius at which data are written for a given data rate. The readback pulse width (in time) decreases with increasing disk velocity, leading to improved pulse resolution at the outer diameter (OD) relative to the inner diameter (ID). Furthermore, the signal-to-noise ratio (SNR) is also the poorest at the ID. The reason for the SNR dependence on radius is that the pulse amplitude for an inductive head increases directly with disk velocity except for losses caused by the flying height increase at higher velocities. The overall noise increases at a somewhat slower rate so that one would expect to observe an increase in SNR moving from ID to OD.

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Track Density Zoning

      It is widely known that in high performance disk files the
largest amount of pulse crowding or intersymbol interference (ISI)
occurs at the smallest radius at which data are written for a given
data rate.  The readback pulse width (in time) decreases with
increasing disk velocity, leading to improved pulse resolution at the
outer diameter (OD) relative to the inner diameter (ID).
Furthermore, the signal-to-noise ratio (SNR) is also the poorest at
the ID. The reason for the SNR dependence on radius is that the pulse
amplitude for an inductive head increases directly with disk velocity
except for losses caused by the flying height increase at higher
velocities.  The overall noise increases at a somewhat slower rate so
that one would expect to observe an increase in SNR moving from ID to
OD. Similarly, the pulse width (in time) decreases with increasing
disk velocity, leading to improved pulse resolution at the OD
relative to the ID.  Therefore, factors which determine the storage
capacity, such as track density and track capacity, are limited by
the error rate performance at the inner track radius.  At larger
radii ISI is decreased and SNR is improved, but the track capacity is
generally held constant.

      Disclosed here is a method of increasing the storage capacity
of a high performance disk file which uses two or more recording
heads per disk surface.  It is proposed that each data band have a
different read head which may be opti...