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Method to recover from bad sector in SSW process

IP.com Disclosure Number: IPCOM000177553D
Publication Date: 2008-Dec-18
Document File: 3 page(s) / 59K

Publishing Venue

The IP.com Prior Art Database

Abstract

In Servo Track Write (STW) self-propagation process, the subsequent patterns can't be written if there is an error servo pattern which has already be written. This document describes how to continue the STW process if there are error servo patterns. The method is to use the servo pattern which is previously recorded in the timing direction.

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Method to recover from bad sector in SSW process

1.Backbround


In Servo Track Write (STW) self-propagation process, all servo patterns are written by its own read and write heads. Read head follows servo patterns and write head writes subsequent servo patterns. Then head moves outwards to follow outer servo pattern and write next subsequent servo patterns. This process continues until sufficient servo patterns are written.

There may be error servo patterns whose servo data can't be recognized correctly. If an error servo pattern exists, the read head can't follow on servo patterns and it is impossible to decide the write position of subsequent servo pattern. Then the self-propagation process stops.

This document describes about the method to continue self-propagation process even if there are error servo patterns.

The method is to use the servo pattern which is previously recorded in the timing direction.

2.Description
(1) How to continue servo write process even if there is an error sector
Servo pattern is consists of preamble pattern which is used for PLL, Servo Address Mark (SAM) which is used to recognize servo pattern, cylinder ID (CYLID), servo sector number (PHSN), burst patterns for precise radial positioning and timing mark to know the timing of servo pattern is read(Fig.1).

If there is at least one which can't be recognized appropriately in SAM, CYLID, PHSN, bursts and timing mark, the servo pattern is defined as an error servo pattern.

When there is no error servo pattern on Xth cylinder, (N+1)th servo sector is written by triggering Nth sector (Fig.2).

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