Browse Prior Art Database

Removal of Spindle Motor Drive During a Data Recovery Read Operation

IP.com Disclosure Number: IPCOM000122620D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 3 page(s) / 83K

Publishing Venue

IBM

Related People

Kerwin, GJ: AUTHOR

Abstract

Described is a means of turning off the disk drive spindle motor, under microprocessor control, during a data recovery procedure (DRP) read operation.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 77% of the total text.

Removal of Spindle Motor Drive During a Data Recovery Read Operation

      Described is a means of turning off the disk drive
spindle motor, under microprocessor control, during a data recovery
procedure (DRP) read operation.

      A disk drive with a spindle speed of 7500 RPM with 53 sectors
per track would yield a time to read the 512 bytes of data in the
sector of 150 microseconds.  If drive to the spindle motor were
removed for 150 microseconds, the speed would be reduced by .002
percent.  This number was derived using the typical 3.5 in disk pack
mass, and therefore inertia, as well as typical spindle load.  The
observed deceleration rate would be approximately 100 radians/sec
squared.  For the data channels that are currently available, the
capture range and response time of the VFO timing loop in tracking
mode would have no problem following this .002 percent speed
reduction.

      Fig. 1 shows both the normal operation of the disk drive as it
reads successive sectors of data as well as a Data Recovery Read
operation using the disclosed read with spindle motor drive off.  In
the first example, Sector B is read normally with the motor drive
circuitry operational. The next example in the figure shows a read of
sector B with the motor coasting.  From an implementation standpoint,
the microprocessor in the disk drive, which is already used to switch
the spindle motor drive from start-up to run mode, turns the spindle
control off with a command issued...