Magnetic Disk Device Track Error Correction and Idle Rewriting
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Solution Overview
Problem
Magnetic disk devices face challenges in improving data quality due to read errors and the limitations of existing error correction capabilities, which can lead to data degradation over time without effective management and rewriting strategies.
Innovation Solution
The magnetic disk device incorporates a track ECC unit for iterative decoding, error correction management, and data rewriting processes, allowing for correction of multiple sector errors and proactive data rewriting during idle periods, thereby maintaining data integrity and preventing error correction capacity overload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error correction is performed on sectors with read errors, then data integrity is improved, but the error correction unit may become overloaded and processing speed decreases
Solution Approach 1:
The system performs error correction in advance during idle periods before data is actually needed. When a read error is detected, the corrected data is stored in a buffer memory, and the correction processing is completed beforehand rather than waiting until the data is requested, thus avoiding delays during actual data retrieval operations
Solution Approach 2:
A buffer memory is introduced as an intermediary between the error correction unit and the data output. The buffer temporarily stores corrected data, allowing the error correction unit to operate independently during idle periods without blocking data retrieval operations, thus decoupling the correction processing from the data access timeline
2Reliability
If data rewriting is performed to correct errors, then data quality is improved, but device complexity and processing overhead increase
Solution Approach 1:
The system uses its own idle processing capacity to perform error correction and data rewriting operations. During periods when no data access requests are pending, the controller automatically identifies and corrects erroneous data on the magnetic disk, making the system self-maintaining without requiring external intervention or additional dedicated correction hardware
Solution Approach 2:
The system dynamically changes the operational state of the error correction unit based on system workload. When idle, the correction unit operates at full capacity to perform rewriting; when data access is required, it suspends rewriting operations. This parameter change in operational mode allows the system to balance data quality improvement with processing efficiency
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
This solution enhances data quality by effectively correcting errors in multiple sectors and managing data rewriting to prevent overload, ensuring reliable data storage and retrieval while extending the error correction capability of the device.
Implementation Method 1
a magnetic head that reads/writes data on the magnetic disk
Data Source
AI summary
According to one embodiment, a magnetic disk device includes a magnetic disk, a storage unit, a magnetic head, an error correction unit that, in a case where an error is detected in user data read by the magnetic head, performs error correction on a sector in which the error is detected in track units and acquires error correction data, and a control unit. The control unit controls reading/writing of user data, management data for managing a sector on which the error correction is performed in the track units, and the error correction data, and in a case where there is no host access, rewrites data on the track including the sector on which the error correction is performed, based on the user data stored in the track and the error correction data of the sector, in which the error is detected, of the track.