Browse Prior Art Database

Hard Disk Data Control Method

IP.com Disclosure Number: IPCOM000103910D
Original Publication Date: 1993-Feb-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Asano, H: AUTHOR

Abstract

This article describes a method to virtually increase the hard disk data transfer rate between the sector buffer and the disk by compressing data over a series of sectors on a same cylinder.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 68% of the total text.

Hard Disk Data Control Method

      This article describes a method to virtually increase the hard
disk data transfer rate between the sector buffer and the disk by
compressing data over a series of sectors on a same cylinder.

      Fig.1 shows the sector format for this method.  The start
sector (address A) and end sector (address B) are filled in with 'FF'
when the data is not compressed.  When the data is to be compressed,
A is filled with the starting sector and B is filled with the end
sector address.

      Fig.2 shows the data write operation.  Data transferred from
Host is stored in Original Data part of the sector buffer without
compression while the same data is stored in Comp Data part in a
compressed format in the cylinder block unit.  The length of data is
compared between the two parts to see compression efficiency.

      The original data is transferred to the disk by setting the
start sector and the end sector with 'FF' if the compression ratio is
more than 1.  The compressed data is transferred to the disk by
setting the start and end sector addresses related to the orginal
data if the compression ratio is less than 1.  Note that the
compressed data occupies a portion of sectors which would be occupied
by original data if it is not compressed so the rest of the sectors
are unoccupied by any data.  The next block of data is written at the
start sector address assigned to that block.  This is because the
purpose of this scheme is to...