Shingled Magnetic Disk Positioning Error Correction
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Solution Overview
Problem
High-density magnetic disk recording technologies, such as shingled write recording, face challenges with positioning errors causing data overwrite issues, requiring large memory to store errors and leading to reduced recording performance due to frequent interruptions in writing.
Innovation Solution
A magnetic disk apparatus that measures read signal quality at shifted radial positions, determines positioning errors using stored read position dependency information, and adjusts target radial positions to prevent data overwrite by using a processor to manage data recording, thereby reducing the need for large memory and improving recording performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If shingled write recording is used to increase recording capacity, then data density is improved, but positioning errors cause data overwrite issues
Solution Approach 1:
The system performs preliminary measurement of read signal quality at multiple radial positions before actual data recording. Based on these measurements, it determines positioning errors and adjusts target radial positions in advance, preventing data overwrite issues before they occur during shingled write recording
Solution Approach 2:
The system measures read signal quality at multiple radial positions, uses this feedback information to determine positioning errors, and then adjusts target radial positions accordingly. This closed-loop feedback mechanism ensures data integrity while maintaining high recording capacity
2Reliability
If large memory is used to store positioning errors of multiple tracks, then data overwrite is prevented, but device complexity increases
Solution Approach 1:
The system extracts only the essential information needed for positioning error correction by measuring read signal quality at selectively shifted radial positions. This reduces the amount of data that needs to be stored and processed compared to storing complete positioning error information for all tracks
Solution Approach 2:
The system applies different measurement strategies based on local conditions by measuring read signal quality at multiple radial positions specifically for tracks where positioning errors are expected. This localized approach reduces overall memory requirements while maintaining effective overwrite prevention
3Reliability
If limit value for positioning error is set small to prevent overwrite, then data integrity is improved, but recording performance decreases due to frequent interruptions
Solution Approach 1:
The system performs preliminary measurement and determination of positioning errors before recording begins. By adjusting target radial positions in advance based on measured read signal quality, it prevents frequent interruptions during recording while maintaining data integrity
Solution Approach 2:
The system enables continuous recording operation by determining positioning errors and adjusting target radial positions before recording starts. This eliminates the need for frequent interruptions that would otherwise occur when using conservative limit values during the recording process
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 effectively prevents data overwrite and maintains recording performance by efficiently managing positioning errors without requiring excessive memory, allowing for higher capacity and reliability in magnetic disk recording.
Implementation Method 1
a magnetic head writing and reading data for the magnetic disk
Implementation Method 2
the processor is configured: to measure read signal quality at a plurality of positions shifted from an average radial position
Data Source
AI summary
A magnetic disk apparatus of one of the embodiments stores read position dependency information on read signal quality of a data region at a first track and measures the read signal quality at a predetermined radial position in a second data region of a second track different from the first track. A positioning error of the second data region is determined based on the read position dependency information and the read signal quality at the predetermined radial position. Data is recorded in a recording target data region in a shingled recording so as to prevent data written in the second data region from being overwritten by data in a recording target data region adjacent to the second data region by using the determined positioning error.