Shingled magnetic recording interband track pitch tuning

Patent metadata

Field	Value
Publication number	US-9607633-B1
Application number	US-201615091945-A
Country	US
Kind code	B1
Filing date	Apr 6, 2016
Priority date	Apr 6, 2016
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

Method and apparatus for positioning shingled magnetic recording (SMR) tracks on a rotatable data storage medium. In some embodiments, a first band of partially overlapping tracks is written the medium at a first track pitch. An adjacent, second band of partially overlapping tracks is written to the medium at the first track pitch. The second band has a first written track at a second track pitch with respect to a last written track in the first band. The second track pitch is determined in response to an error rate established for a test track using an adjacent track written at the first track pitch.

First claim

What is claimed is:

1. A method comprising:
writing a first band of partially overlapping tracks to a rotatable recording medium at a first track pitch; and
writing an adjacent second band of partially overlapping tracks to the rotatable recording medium at the first track pitch, the second band comprising a first written track that is adjacent a last written track in the first band, the first written track in the second band placed at a second track pitch from the last written track in the first band determined in response to an error rate established for a test track using an adjacent track written at the first track pitch.

2. The method of claim 1 , further comprising:
performing a first single sided track squeeze operation comprising writing a first target track on the medium, and repetitively writing a first adjacent track on a first selected side of the first target track with successively greater overlap distances on the first target track until a specified error rate value is obtained from the target track for a first final overlap distance;
performing a second single sided track squeeze operation comprising writing a second target track on the medium, and repetitively writing a second adjacent track on an opposing, second selected side of the second target track at successively closer greater overlap distances on the second target track until the specified error rate value is obtained for a second final overlap distance; and
selecting the first track pitch in relation to a greater one of the first final overlap distance or the second final overlap distance.

3. The method of claim 2 , wherein the first track pitch is further selected in relation to a write fault threshold (WFT) value associated with the target track.

4. The method of claim 2 , further comprising selecting a shingling direction for each of the tracks in the first band and in the second band responsive to the greater one of the first final overlap distance or the second final overlap distance.

5. The method of claim 2 , further comprising:
performing a double sided track squeeze operation comprising writing a third test track on the medium, writing a third adjacent track at the first track pitch with respect to the third test track on the first selected side or the second selected side of the target track corresponding to the greater one of the first final overlap distance or the second final overlap distance, and repetitively writing a fourth adjacent track on the remaining one of the first selected side or the second selected side of the target track at successively greater overlap distances on the third target track until the specified error rate value is obtained for a third final overlap distance; and
selecting the second track pitch in relation to the third final overlap distance and the first track pitch.

6. The method of claim 1 , further comprising prior steps of:
writing a test pattern to a test track at a selected location on the medium;
writing a first adjacent track that partially overlaps the test track in a first radial direction of the medium at the first track pitch value;
while maintaining the first adjacent track at the first track pitch with respect to the test track, performing steps of writing a second adjacent track that partially overlaps the test track in an opposing second radial direction of the medium, measuring an initial error rate value from the test track, and repetitively advancing the second adjacent track toward the test track by rewriting the second adjacent track and determining an updated error rate value from the test track until a specified error rate value for the target track is reached at a final squeeze distance for the second adjacent track; and
determining the second track pitch value responsive to the final squeeze distance.

7. A method comprising sequential steps of:
writing a test pattern to a test track using a data transducer adjacent a rotatable data recording medium;
writing a first adjacent track that partially overlaps the test track in a first radial direction of the medium at a first track pitch value;
while maintaining the first adjacent track at the first track pitch with respect to the test track, performing steps of writing a second adjacent track that partially overlaps the test track in an opposing second radial direction of the medium, measuring an initial error rate value from the test track, and repetitively advancing the second adjacent track toward the test track by rewriting the second adjacent track and determining an updated error rate value from the test track until a specified error rate value for the target track is reached at a final squeeze distance for the second adjacent track;
determining a second track pitch value responsive to the final squeeze distance; and
writing first and second bands of partially overlapping tracks to the medium, each of the tracks in the respective first and second bands written at the first track pitch, a last track in the first band and a first track in second band written at the second track pitch.

8. The method of claim 7 , further comprising prior steps of:
performing a first single sided track squeeze operation comprising writing a first target track on the medium, and repetitively writing a first adjacent track on a first selected side of the first target track with successively greater overlap distances on the first target track until a specified error rate value is obtained from the target track for a first final overlap distance;
performing a second single sided track squeeze operation comprising writing a second target track on the medium, and repetitively writing a second adjacent track on an opposing, second selected side of the second target track at successively closer greater overlap distances on the second target track until the specified error rate value is obtained for a second final overlap distance; and
selecting the first track pitch in relation to a greater one of the first final overlap distance or the second final overlap distance.

9. The method of claim 7 , wherein the first track pitch is further selected in relation to a write fault threshold (WFT) value associated with the target track.

10. The method of claim 7 , further comprising selecting a shingling direction for each of the tracks in the first band and in the second band responsive to the greater one of the first final overlap distance or the second final overlap distance.

11. The method of claim 7 , wherein the first track pitch is determined by prior steps comprising:
writing a test pattern to a test track on the medium;
writing a third adjacent track that partially overlaps the test track in the first radial direction of the medium;
reading the test pattern from the test track to determine an initial error rate value;
repetitively advancing the third adjacent track toward the test track by rewriting the third adjacent track and determining an updated error rate value until a specified error rate value for the target track is reached at a first final squeeze distance for the third adjacent track;
rewriting the test pattern to the test track;
writing a fourth adjacent track that partially overlaps the test track in the opposing second radial direction of the medium;
reading the test pattern from the test track to determine an initial error rate value;
repetitively advancing the fourth adjacent track toward the test track by rewriting the fourth adjacent track and determining an updated error rate value until a specified error rate value for the target track is reached at a second final squeeze distance for the third adjacent track; and
selecting the first track pitch in relation to a greater one of the first f

Assignees

• Seagate Technology Llc

Inventors

• Toribio Jose Mari Corral
• Teo Song Wee
• Lim Teck Khoon

Classifications

• G11B20/182 Primary

  using test patterns · CPC title

• G11B5/012 Primary

  Recording on, or reproducing or erasing from, magnetic disks (G11B17/00, G11B19/00 take precedence) · CPC title

• G11B20/1217

  on discs · CPC title

• G11B2020/1242

  the area forming one or more zones, wherein each zone is shaped like an annulus or a circular sector · CPC title

• G11B5/56

  with provision for moving the head {support} for the purpose of adjusting the position of the head relative to the record carrier, e.g. manual adjustment for azimuth correction or track centering ({G11B5/52,} G11B5/54, G11B5/58 take precedence) · CPC title