Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Data Recovery with Adaptive Sync Field Length

IP.com Disclosure Number: IPCOM000114160D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Kurachi, K: AUTHOR [+4]

Abstract

This article describes the new scheme to rescue hard errors of Hard Disk Drive (HDD) caused by defects on sync field and VFO unlock. Appling several steps to change length of sync field to Data Recovery Procedure, we could perfectly rescue hard errors by defects on sync field.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Data Recovery with Adaptive Sync Field Length

      This article describes the new scheme to rescue hard errors of
Hard Disk Drive (HDD) caused by defects on sync field and VFO unlock.
Appling several steps to change length of sync field to Data Recovery
Procedure, we could perfectly rescue hard errors by defects on sync
field.

      On each sector of HDD, there are several field of Sync, Address
Mark, Data, ECC, PAD (Fig. 1).

      Fig. 2 shows SYNC Field format, defect position, peak detection
signal and timing of Read Gate and PLL of the channel.

      In the middle of the SYNC field, PLL mode changes from High
gain mode to normal gain mode for VFO to be locked.  But when there
are defects around this mode-change timing, these defects become the
cause of bit-shift so that PLL cannot be locked and error will occur.
This error cannot correct by ECC because ECC affects data area only.

      This invention can solve this problem by changing rise timing
of Read Gate by 5nsec forward and backward and changing PLL mode
change
timing as the same.  We inserted this sequence into the Data Recovery
Procedure and 100% rescued hard errors.