Magnetic Disk Shingled Write Track Positioning Error Correction
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Solution Overview
Problem
In high-density magnetic disk recording, positioning errors of the write head lead to track misalignment, which can result in data overwrite or loss, and existing techniques fail to accurately manage these errors to prevent track narrowing and maintain data integrity during shingled write recording.
Innovation Solution
A magnetic disk apparatus that uses a processor to detect and store positioning errors from servo areas, updates these errors based on adjacent tracks, and employs methods to prevent track narrowing by adjusting the target position of the write head, either by stopping the write process or correcting the head's radial position to maintain constant track width, thereby reducing the dispersion of track width and preventing data loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If tracks are written at high density using shingled write recording, then recording capacity is increased, but positioning error causes track misalignment and data overwrite
Solution Approach 1:
The system performs preliminary actions by detecting positioning errors in servo areas before data writing, storing these errors, and using them to correct target writing positions. This preventive approach ensures that even with positioning errors, tracks are written at high density without data overwrite or loss.
Solution Approach 2:
The system implements feedback by reading position information from servo areas, detecting positioning errors, storing these errors, and using them to adjust target writing positions for subsequent tracks. This closed-loop feedback mechanism maintains data integrity while enabling high-density shingled write recording.
2Reliability
If positioning error is reduced to write data with high accuracy, then data integrity is improved, but it is difficult to reduce positioning error dramatically due to disturbance
Solution Approach 1:
The system changes parameters by detecting positioning errors in servo areas and using these detected errors to adjust target writing positions. Instead of trying to reduce positioning error through complex hardware improvements, the system adapts to the errors by modifying writing parameters (target positions) based on detected positioning deviations.
3Measurement precision
If a track is rewritten due to positioning error, then data accuracy is improved, but already written data may be destroyed or writing speed decreases
Solution Approach 1:
The system performs preliminary detection of positioning errors in servo areas before data writing and calculates corrected target positions in advance. This prevents the need for rewriting by ensuring accurate positioning from the first write operation, thereby maintaining high writing speed while ensuring track positioning accuracy.
4Reliability
If target position is adjusted to prevent track narrowing, then data loss is prevented, but track width dispersion increases without proper management
Solution Approach 1:
The system uses feedback from detected positioning errors to adjust target writing positions, preventing track narrowing while maintaining consistent track width. By continuously monitoring positioning errors and adjusting target positions accordingly, the system prevents data loss without causing excessive track width dispersion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces the likelihood of data overwrite or loss by accurately managing positioning errors, maintaining track width consistency, and minimizing the standard deviation of track width dispersion, thus enhancing data storage reliability in shingled write recording systems.
Implementation Method 1
by reading the position information of the servo areas of the first track by the magnetic head
Implementation Method 2
Since data is written in a track by a write head
Data Source
AI summary
According to one embodiment, a magnetic disk apparatus includes a magnetic disk having a plurality of tracks, each of the plurality of tracks having a plurality of servo areas and a plurality of data areas, the plurality of servo areas and the plurality of data areas being alternately arranged respectively, a magnetic head, and a processor. When a plurality of positioning errors related to one servo area are present in the first track, the processor updates the positioning error of the one servo area with a positioning error closest to a second track that is next to the first track. The processor writes data in the second track by a shingled write recording system by using the updated positioning error.