Magnetic Disk Write Processing Adaptive Off-Track Control
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Solution Overview
Problem
Magnetic disk devices face challenges in achieving high track per inch (TPI) due to limitations in write processing, as they prohibit writing when the head exceeds an allowable off-track value, leading to difficulties in data recording capacity and reliability.
Innovation Solution
The magnetic disk device employs a controller to dynamically adjust the allowable write values for each sector based on the error rates of adjacent tracks, allowing for more precise head positioning and expanded write capabilities while maintaining data readability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the head position is strictly controlled to prohibit write processing when exceeding the allowable off-track value, then data writing reliability is improved, but track pitch cannot be narrowed and TPI cannot be increased
Solution Approach 1:
The patent applies dynamics by making the allowable off-track value variable rather than fixed. The controller dynamically adjusts the allowable off-track value based on the actual error rate of the adjacent track, allowing the write prohibition threshold to adapt to real conditions. When error rates are low, larger off-track values are permitted; when error rates are high, smaller off-track values are enforced. This dynamic adjustment resolves the contradiction by enabling narrower track pitches while maintaining reliability through adaptive control.
Solution Approach 2:
The patent changes the parameter of the allowable off-track value from a constant to a variable that depends on the adjacent track's error rate. By monitoring the error rate and adjusting the allowable off-track threshold accordingly, the system can permit tighter track spacing when conditions allow while maintaining data integrity when conditions deteriorate. This parameter change enables the resolution of the contradiction between reliability and track pitch reduction.
2Reliability
If the allowable off-track value is set conservatively to ensure data readability, then write processing reliability is improved, but write processing interruptions increase and productivity decreases
Solution Approach 1:
The patent implements feedback by continuously monitoring the error rate of the adjacent track and using this information to adjust the allowable off-track value for write operations. This closed-loop control allows the system to respond to actual track conditions, permitting more aggressive write thresholds when error rates are low (improving productivity) while automatically tightening thresholds when error rates increase (maintaining reliability). The feedback mechanism resolves the contradiction by enabling adaptive write processing that optimizes both reliability and efficiency.
Solution Approach 2:
The patent applies preliminary action by proactively adjusting the allowable off-track value based on predicted or measured error rates before write operations occur. By anticipating potential issues through error rate monitoring and pre-adjusting the write thresholds, the system prevents write interruptions rather than reacting to them after they occur. This preliminary adjustment resolves the contradiction by maintaining reliability through advance preparation while maximizing productivity through optimized write parameters.
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 approach enhances data recording capacity by allowing for narrower track pitches and improved reliability by adjusting write thresholds based on adjacent track error rates, thereby optimizing write processing and reducing the frequency of write processing interruptions.
Implementation Method 1
a head configured to write data to the disk and read data from the disk
Implementation Method 2
a head configured to write data to the disk and read data from the disk
Data Source
AI summary
According to one embodiment, a magnetic disk device includes a disk, a head configured to write data to the disk and read data from the disk, and a controller configured to control the head to write a first track based on a first error rate read immediately after writing a second track adjacent in a radial direction of the disk to the first track.