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Browse Prior Art Database

Surface Analysis for Increased Capacity

IP.com Disclosure Number: IPCOM000119231D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 1 page(s) / 47K

Publishing Venue

IBM

Related People

Cunningham, EA: AUTHOR [+3]

Abstract

In Direct Access Storage Devices (DASDs), the error rate of different head/disk combinations varies greatly. The design of standard DASD allows for the worst combinations so that almost all produce adequate results, resulting in good final test yield. Disclosed is an invention that allows head/disk combinations to be used closer to their individual full capability, thus providing an increased capacity while using nearly standard file architecture design and tests.

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This is the abbreviated version, containing approximately 66% of the total text.

Surface Analysis for Increased Capacity

      In Direct Access Storage Devices (DASDs), the error rate
of different head/disk combinations varies greatly.  The design of
standard DASD allows for the worst combinations so that almost all
produce adequate results, resulting in good final test yield.
Disclosed is an invention that allows head/disk combinations to be
used closer to their individual full capability, thus providing an
increased capacity while using nearly standard file architecture
design and tests.

      The increase in DASD capacity is accomplished by using a higher
recording density than normally used for adequate final error rate
test yield.  Some of the worst sectors are then removed to improve
the error rate to an acceptable level, and a net capacity improvement
is obtained in the process.

      The method of removing the high error rate sectors is done
using a Surface Analysis Test (SAT) in the form of standard data
processing.  This test, which is designed to remove defective
sectors, is also sensitive to high background error rate.  Since the
recorded density is increased in this method, there is often one
head/disk combination that would exceed the error rate
specifications, with most of the errors being generated at the inner
tracks, where the linear density is highest.  By identifying and
removing the high error rate sectors, in addition to the defective
sectors, the error rate can be controlled while the capacity is
higher than tha...