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Browse Prior Art Database

Adaptive Skew for Hard Disk Drive

IP.com Disclosure Number: IPCOM000117609D
Original Publication Date: 1996-Apr-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Kagami, N: AUTHOR [+3]

Abstract

Disclosed is a design for Hard Disk Drives (HDD). Track skew, cylinder skew is optimized for every drive so that the data transfer rate is not affected by mechanical distortion of the drive.

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This is the abbreviated version, containing approximately 100% of the total text.

Adaptive Skew for Hard Disk Drive

      Disclosed is a design for Hard Disk Drives (HDD).  Track skew,
cylinder skew is optimized for every drive so that the data transfer
rate is not affected by mechanical distortion of the drive.

      Mechanical distortion and read / write element offset of the MR
head causes tilt.  Tilt is defined as the offset of the tracks in
adjacent heads in a cylinder.  Data in HDD is stored in cylindrical
format or cylinders.  Consecutive data is written on adjacent heads
in the same cylinder.  Although it is designed that seeking motion is
not necessary, since tilt exists some skew is provided after head
switch before the consecutive data starts.  This is called track
skew.  The skew between adjacent cylinders after the last head is
called cylinder skew.  These skew should be minimized for transfer
rate performance but at the same time, it must be large enough to
tolerate the variances in tilt.  When the seeking motion is not
completed during this skew, the drive must wait an entire revolution
before reading or writing data.

      Since the sum of track skew between heads and the cylinder skew
decide the total skew time, optimizing each skew and keeping this
value constant is very effective in improving transfer speed.
Implementing the  same skew for every head in every drive such as the
existing method is  wasteful.