Offset-Reading Retry Mechanism for Magnetic Disk Data Accuracy
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Solution Overview
Problem
Conventional methods for handling read-errors in magnetic disk devices due to offset-writing result in uncertainty about which data is correct when new data is offset-written over old data, leading to incorrect data being read during offset-reading.
Innovation Solution
A storage device and method that performs offset-reading retries in both inner and outer directions towards the center and circumference of the storage medium, comparing the read data from both directions to ensure data accuracy and output the correct data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If offset-reading is performed to handle read-errors, then data recovery capability is improved, but data accuracy deteriorates because it is not known which data is correct when new data is offset-written over old data
Solution Approach 1:
The patent divides the offset-reading process into multiple segments by performing reading operations at different offset positions (first offset position and second offset position). This segmentation allows the system to read data from multiple locations and compare them to determine correctness, resolving the ambiguity of which data is correct when offset-writing occurs.
Solution Approach 2:
The patent implements a feedback mechanism where the read gain information obtained during offset-reading is fed back to adjust subsequent reading operations. By using the read gain from the first offset reading to determine the second offset position, the system continuously refines its data recovery process to improve accuracy while maintaining reliability.
2Productivity
If the read-head core size is reduced to increase reading speed, then productivity is improved, but manufacturing precision requirements increase because smaller heads are more sensitive to offset-writing deviations
Solution Approach 1:
The patent changes the operational parameters of the read-head by dynamically adjusting offset positions and reading gains based on real-time read errors and read gain information. This allows the system to compensate for the reduced precision inherent in smaller read-heads, maintaining reliable data recovery despite the manufacturing precision limitations of miniaturized heads.
Data Source
AI summary
A data reading unit reads inner offset data from an offset reading in an inner direction toward a center of a storage medium and outer offset data from an offset reading in an outer direction toward a circumference of the storage medium. A data comparing unit compares the inner offset data and the outer offset data read by the data reading unit. A data-output control unit that outputs the read-data when a result of comparison by the data comparing unit indicates that the inner offset data matches the outer offset data.