# US 2006/0066971 A1 · System and method for ameliorating the effects of adjacent track erasure in magnetic data storage device

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- Number: US 2006/0066971 A1
- Document ID: US20060066971A1
- Status: Published application
- Kind: A1
- Application number: 10/956,898
- Filed: 2004-09-30
- Published: 2006-03-30
- Earliest claimed: 2004-09-30
- Assignees: Hitachi Global Storage Technologies Netherlands B.V.
- Inventors: Michael Alex; Hideki Zaitsu
- Web page: https://patentgrep.com/patent/US20060066971A1

## CPC

- G11B 5/012: Recording on, or reproducing or erasing from, magnetic disks (G11B17/00, G11B19/00 take precedence)
- G11B 20/10: Digital recording or reproducing
- G11B 2220/2516: Hard disks
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

To ameliorate the effects of ATE in a HDD, tracks that are potential victim tracks of an aggressor track by virtue of the victim tracks being exposed to a magnetic field associated with a write of the aggressor track are preemptively rewritten after an empirically-determined number of writes to the aggressor track, with the empirically-determined number of writes being selected to ensure that the cumulative effects of aggressor writes do not rise to the level that would be expected to result in a significant amount of lost data on the victim tracks. Alternatively, potential victim tracks can be scanned for error rates and if any error rates violate a threshold, the victim tracks can be rewritten when the disk is idle.

## Claims

### Claim 1

A controller for a hard disk drive (HDD) and executing logic, the logic comprising:
correlating at least one aggressor track on a disk of the HDD to at least one victim track on the disk;
scanning at least one victim track for errors; and
if the errors violate a threshold, determining that the victim track must be rewritten.

### Claim 2

A controller for a hard disk drive (HDD) and executing logic, the logic comprising:
correlating at least one aggressor track on a disk of the HDD to at least one victim track on the disk;
counting a number of times the aggressor track is written to; and
when the number of times violates a threshold, rewriting data on the victim track.

### Claim 3 (depends on 2)

The controller of claim 2, comprising determining whether a victim track holds any data, prior to executing the rewriting act.

### Claim 4 (depends on 2)

The controller of claim 2, wherein a track is a victim track of an aggressor track by virtue of the victim track being exposed to a magnetic field associated with a write of the aggressor track.

### Claim 5 (depends on 2)

The controller of claim 2, wherein the logic includes:
scanning at least one victim track for errors; and
if the errors violate a threshold, determining that the victim track must be rewritten.

### Claim 6 (depends on 5)

The controller of claim 5, wherein a track is a victim track of an aggressor track by virtue of the victim track being exposed to a magnetic field associated with a write of the aggressor track.

### Claim 7 (depends on 5)

The controller of claim 5, wherein the victim track is scanned at predetermined intervals.

### Claim 8 (depends on 5)

The controller of claim 5, wherein the victim track is scanned after a predetermined number of writes.

### Claim 9 (depends on 1)

The controller of claim 1, wherein the victim track is scanned for an error rate.

### Claim 10 (depends on 1)

The controller of claim 1, wherein the logic includes rewriting any victim tracks having errors violating the threshold only when the HDD is idle.

### Claim at position 11

11-16. (canceled)

### Claim 17

A chip for a hard disk drive (HDD) having data tracks, wherein at least one victim track is correlated to at least one aggressor track by virtue of the victim track being expected to receive exposure to stray magnetic flux when the aggressor track is written to, comprising:
means for determining whether a rewrite condition has been met; and
means for rewriting data stored on the victim track back to the victim track, responsive to the means for determining.

### Claim 18 (depends on 17)

The chip of claim 17, wherein the rewrite condition is a number of writes to the aggressor track.

### Claim 19 (depends on 17)

The chip of claim 17, wherein the rewrite condition is an error rate associated with the victim track.

### Claim 20 (depends on 17)

The chip of claim 17, wherein the error rate is determined at predetermined intervals.

### Claim 21 (depends on 17)

The chip of claim 17, wherein the error rate is determined after a predetermined number of writes.