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A data recovery method from thermal asperities

IP.com Disclosure Number: IPCOM000013852D
Original Publication Date: 1999-Dec-01
Included in the Prior Art Database: 2003-Jun-18
Document File: 1 page(s) / 27K

Publishing Venue

IBM

Related People

Toshihide Ishioka: AUTHOR [+4]

Abstract

TA(Thermal Asperity) is well known as one of the predominant hard failure mechanism of HDD(Hard Disk Drive) which utilizes MR and or GMR heads. This technical disclosure reveals a data recovery method from TA without any hardware change to the HDD.

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A data recovery method from thermal asperities

 TA(Thermal Asperity) is well known as one of the predominant hard failure
mechanism of HDD(Hard Disk Drive) which utilizes MR and or GMR heads. This
technical disclosure reveals a data recovery method from TA without any hardware
change to the HDD.

When MR/GMR read element flies on a TA, the interference between them causes
short term temperature rise on the element and
disturbs read back signal in a certain decay. So if TA can be removed by some
means, the data can be read without error.

On the other hand it is well known phenomena that a write element of HDD head
protrudes from the ABS(air bearing slider) surface when write current is applied.
This means that while writing data on a track, the write element flies lower
than MR/GMR read element and have more chance to hook thermal asperities existing
on the disk surface. This means that this phenomena can remove the TA on the
disk. i.e. When encountered with TA, repeat write operation on healthy sector on
the same track and let the write head protruded and hook TA, then read the
errored sector and secure the data.

Followings are the typical algorithm samples for this method.

When a data error which is supposed to be caused by
TA.
1. Read whole track data other than errored sector
2. Reassigns the sectors read in step 1
3. Write all or a part of the sectors read in step
1

4. Repeat step 3 for a while to hook TA.
5. Read originally errored sector
6. If fail, repeat 3 to 5 again.
7. (This...