Magnetic Disk Track Pitch Control for Data Quality
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Solution Overview
Problem
Magnetic disk devices face challenges in maintaining data quality due to the narrowing track pitch in shingled magnetic recording (SMR), which can lead to errors during read operations, especially when error correction codes are not effectively written or are invalid, resulting in inferior data quality.
Innovation Solution
The magnetic disk device includes a control circuit that determines the effectiveness of error correction codes on adjacent tracks and adjusts the track pitch accordingly, either maintaining a narrower pitch when codes are valid or widening it when codes are invalid to prevent data quality deterioration, and utilizes a temporary region for incomplete data writes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the track pitch is narrowed to increase storage capacity in SMR, then the storage density is improved, but the data quality deteriorates due to read errors
Solution Approach 1:
The patent applies preliminary action by writing error correction codes (ECC) to tracks before data writing operations. The control circuit determines ECC effectiveness in advance and sets the track pitch accordingly before actual data storage, preventing data quality issues rather than correcting them after occurrence. This proactive approach ensures that tracks with invalid ECC are identified and handled with appropriate pitch adjustments before they can cause read errors.
Solution Approach 2:
The patent dynamically changes the track pitch parameter based on ECC validity. When ECC is determined to be invalid or ineffective, the control circuit increases the track pitch to create larger safety margins between tracks, compensating for the lack of error correction capability. This parameter adjustment resolves the contradiction by adapting the physical track configuration to the actual error correction status, maintaining data reliability while maximizing storage capacity where ECC is valid.
2Reliability
If error correction codes are written to all tracks, then data quality is improved, but the device complexity increases
Solution Approach 1:
The patent applies local quality by differentiating track treatment based on individual ECC validity rather than applying uniform error correction to all tracks. The control circuit assesses ECC effectiveness on a per-track basis and applies different track pitch strategies: narrower pitch for tracks with valid ECC and wider pitch for tracks with invalid ECC. This localized approach optimizes storage capacity in regions where ECC works properly while maintaining reliability in regions where it doesn't, without the overhead of complex universal error correction mechanisms.
Solution Approach 2:
The system uses the existing ECC infrastructure to inform track pitch decisions rather than adding a separate complex control mechanism. The control circuit leverages the ECC validity information already generated during track preparation to automatically adjust pitch settings, making the system self-regulating. This approach minimizes additional complexity by reusing existing error correction data for pitch optimization decisions.
3Reliability
If the track pitch is dynamically adjusted based on ECC validity, then data quality is maintained, but the ease of operation deteriorates
Solution Approach 1:
The patent implements feedback by using ECC validity detection results to automatically adjust track pitch settings. The control circuit continuously monitors ECC effectiveness and responds by modifying the track pitch in real-time, creating a closed-loop control system. This automatic feedback mechanism eliminates the need for manual intervention or complex user decisions about pitch settings, as the system self-adjusts based on actual error correction performance, maintaining simplicity from the user perspective while ensuring data quality.
Data Source
AI summary
According to an embodiment, the magnetic disk device includes a disk medium and a control circuit. The disk medium includes a first region including a first track. The control circuit controls a write operation of first data to the first track, executes error correction coding of the first data during the write operation. The control circuit makes first determination on whether the written first data is protected by an error correction code. The control circuit sets a second track in a location adjacent to the first track in accordance with a result of the first determination.