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Browse Prior Art Database

Synchronized Index Pulse for Staggered Servo Pattern

IP.com Disclosure Number: IPCOM000111502D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Kubo, M: AUTHOR [+3]

Abstract

Disclosed here is the method to generate a Synchronized Index Pulse (1 Index Pulse per one rotation) on the HDD which has a Staggered Servo Pattern (2 or more Index Pulses per rotation).

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

Synchronized Index Pulse for Staggered Servo Pattern

      Disclosed here is the method to generate a Synchronized Index
Pulse (1 Index Pulse per one rotation) on the HDD which has a
Staggered Servo Pattern (2 or more Index Pulses per rotation).

      The Synchronized Index Pulse makes it possible for HDD, which
has a Staggered Servo Pattern, to realize Spindle Synchronization.
Spindle Synchronization is the key technology to make a Disk Array
System.

      The Disk Array System is made up of several HDDs which rotate
synchronously.  This is called Spindle Synchronization.  In order to
realize Spindle Synchronization, all HDDs should have an Index Pulse
presented once per rotation.

      The Servo Pattern can't be written on several tracks at the
same time.  So, the Servo Pattern is 1/4 sector delayed from the
previous track (Fig. 1).

      The Index Pulse presents the position of the "Index" of the
Head which is currently selected.  Therefore, when Head-switch
occurrs the Index Pulse is presented more than once per rotation.
Please see Fig. 2 for the case when the Head-switch occurrs from Head
1 to 3.  Such an Index Pulse makes HDDs impossible to rotate
synchronously.

      Thus, the Synchronized Index Pulse generates an Index Pulse
once per rotation for HDDs which have a Staggered Servo Pattern.
Fig. 3 shows how to generate the Synchronized Index Pulse.