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Variable Correction Span Error Correction Guide for Improved Throughput And Data Integrity

IP.com Disclosure Number: IPCOM000102975D
Original Publication Date: 1990-Apr-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 49K

Publishing Venue

IBM

Related People

Johnson, JE: AUTHOR

Abstract

Described is a process for simultaneously improving data integrity and throughput of a direct access storage device (DASD) by incorporating into the data recovery procedure (DRP) an error correction code (ECC) that utilizes a variable correction span.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 76% of the total text.

Variable Correction Span Error Correction Guide for Improved Throughput And Data Integrity

      Described is a process for simultaneously improving data
integrity and throughput of a direct access storage device (DASD) by
incorporating into the data recovery procedure (DRP) an error
correction code (ECC) that utilizes a variable correction span.

      Bit-level burst correcting ECC implementations allow for
user-controlled selection of the correction span. Typically, a single
value of correction span is chosen to be used throughout the DRP.  If
the correction span is chosen small to protect against miscorrection,
excessive hard errors can result due to the errors with burst lengths
that exceed the chosen correction span (uncorrectable errors). If the
correction span is chosen large so that more errors are corrected,
the resulting decreased detection span and increased probability of
miscorrection can result in a miscorrection which passes bad data to
the user.

      The correction span is set with microcode and can be altered
during the DRP to provide a more optimum system in terms of both
throughput and data integrity.

      Initially, the correction span is set at a relatively small
number chosen to be large enough to correct the small media defects
that often occur, yet small enough to take advantage of the resulting
large detection span and low probability of miscorrect.  This small
correction span is used in the early stages of DRP, and correction...