Heat assisted magnetic recording for bit-patterned media

• US 9,524,743 B2
• Filed: 06/09/2015
• Issued: 12/20/2016
• Est. Priority Date: 11/24/2014
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Zhu, Wenzhong, Gao, Kaizhong, Gage, Edward
• Primary Examiner(s): BUTCHER, BRIAN M
• Application Number:
  US14/734,235
• Publication Number:
  US 20160148635A1
• Time in Patent Office: 560 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G11B 2005/0021 Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal
• CPC Class Codes: G11B 2220/252 Patterned or quantised magnetic media, i.e. bits are stored in predefined single domain elements
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: G11B 5/09 Digital recording
• CPC Class Codes: G11B 5/746 Bit Patterned record carriers, wherein each magnetic isolated data island corresponds to a bit
• CPC Class Codes: G11B 7/1263 Power control during transducing, e.g. by monitoring

Abstract

A heat-assisted magnetic recording (HAMR) device includes a controller that selects a power for operating a heat source for a data write to a target data track. According to one implementation, the controller selects the power based on an assessment of whether the target data track is bounded by any data-storing tracks. A first power is selected when the data track is not bounded by any data-storing tracks and a second lower power is selected when the data track is bounded by one or more data-storing tracks. In another implementation, the controller writes to different partitioned regions of a storage media with different powers of the heat source. The controller selects a storage location for data based on an expected write error rate and environmental conditions within the HAMR device.

Claims

1. A storage device comprising:

a heat-assisted magnetic recording (HAMR) head including a heat source; and

a controller that selects a power for the heat source to write data to a target data track based on whether the target data track is bounded by any data-storing tracks, the controller configured to relax a positioning requirement of the HAMR head when writing data while operating the heat source at a first power and tighten the positioning requirement of the HAMR head while operating the heat source at a second power.

2. The storage device of claim 1, wherein the controller selects the first power if the target data track is not bounded by any data-storing tracks and selects the second power which is lower than the first power if the target data track is bounded by at least one data-storing track.

3. The storage device of claim 2, wherein the controller is configured to write data to a series of alternating data tracks at the first power until a capacity condition is satisfied.

4. The storage device of claim 1, wherein the storage device includes a bit patterned medium (BPM).

5. One or more non-transitory computer-readable storage media encoding computer-executable instructions for executing on a computer system a computer process, the computer process comprising:

operating a heat-assisted magnetic recording (HAMR) head heat source at a first power to write data to a target data track of a storage medium;

receiving an instruction to re-write the target data track; and

determining whether the target data track is bounded by a data-storing track; and

based on the determination, selecting a second lower power if the target data track is directly adjacent to one or more data storing tracks.

6. The one or more non-transitory computer-readable storage media of claim 5, wherein the computer process further comprises:

selecting the first power if the target data track is not directly adjacent to one or more data-storing tracks.

7. The one or more non-transitory computer-readable storage media of claim 5, wherein the target data track is a data track of a bit patterned medium (BPM).

8. The one or more non-transitory computer-readable storage media of claim 5, wherein the computer process further comprises:

implementing a first positioning requirement for the HAMR head when operating the heat source at the first power;

implementing a second positioning requirement for the HAMR head when operating the heat source at the second lower power, the first positioning requirement being relaxed relative to the second positioning requirement.

9. One or more non-transitory computer-readable storage media encoding computer-executable instructions for executing on a computer system a computer process, the computer process comprising:

selecting between a first region and a second region of a storage medium to write data of a write command;

if the first region is selected, writing data to a series of alternating data tracks while operating a heat assisted magnetic recording (HAMR) head heat source at a first power; and

if the second region is selected, writing data to a series of directly adjacent consecutive data tracks while operating the HAMR head heat source at a second power lower than the first power.

10. The one or more non-transitory computer-readable storage media of claim 9, wherein the first region is a cache region and the computer process further comprises:

initially writing new data to the first region and moving the data to the second region during an idle period of a storage device.

11. The one or more non-transitory computer-readable storage media of claim 9, wherein the computer process further comprises:

calculating an expected write error rate for writing data to the storage medium, the expected error rate based on environmental conditions within a recording device.

12. The one or more non-transitory computer-readable storage media of claim 11, further comprising:

selecting between the first region and the second region based on the expected error rate.

13. The one or more non-transitory computer-readable storage media of claim 11, wherein the computer process further comprises:

if the expected error rate satisfies an error tolerance condition, writing data of the write command to the first region of the storage medium while operating the HAMR head heat source at the first power.

14. The one or more non-transitory computer-readable storage media of claim 13, wherein the error tolerance condition is provided by a host device.

15. The one or more non-transitory computer-readable storage media of claim 13, wherein the computer process further comprises:

if the expected error rate does not satisfy the error tolerance condition, writing data of the write command to the second region of the storage medium while operating the HAMR head heat source at the second power.

16. The one or more non-transitory computer-readable storage media of claim 9, wherein a positioning requirement of the HAMR head is relaxed within the first region relative to the second region.

17. The one or more non-transitory computer-readable storage media of claim 11, wherein the environmental conditions within the recording device include vibrations.

18. The one or more non-transitory computer-readable storage media of claim 11, wherein the environmental conditions within the recording device include temperature.