Magnetic Disk Write Control for Adjacent Track Damage Assessment
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Solution Overview
Problem
Existing magnetic disk apparatuses face challenges in protecting data written to adjacent tracks due to track error correction limitations, leading to potential data loss when adjacent track data cannot be corrected, necessitating premature termination of writing operations.
Innovation Solution
A magnetic disk apparatus with a controller that evaluates the damage on adjacent tracks during writing, using a second calculation method to assess signal quality and adjust write operations based on a squeeze amount threshold, thereby reducing the frequency of protection operations and improving write performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protective operations are executed frequently to protect adjacent track data, then data reliability is improved, but writing performance deteriorates
Solution Approach 1:
The patent changes the parameter of damage evaluation from binary (damaged/not damaged) to continuous (damage amount quantification). By calculating a damage amount based on positional error signals and comparing it with a threshold, the system dynamically adjusts protective operation frequency, reducing unnecessary protections while ensuring data reliability when actual damage risk exists.
Solution Approach 2:
The patent implements feedback by continuously monitoring positional error signals during writing and using this information to evaluate potential damage to adjacent tracks. This feedback loop allows the system to make real-time decisions about whether protective operations are necessary, optimizing the balance between data protection and writing performance.
2Reliability
If track error correction is used to protect adjacent track data, then data protection is improved, but data loss still occurs when correction limits are exceeded
Solution Approach 1:
The patent performs preliminary damage evaluation before writing completes by monitoring positional error signals during the writing process. When the calculated damage amount exceeds a threshold, the system proactively interrupts writing and executes protective operations, preventing potential data loss rather than relying solely on post-write error correction.
Solution Approach 2:
The patent prepares protective measures in advance by evaluating damage risk during writing. When risk exceeds thresholds, protective operations are triggered before data loss can occur, cushioning against potential errors that would otherwise exceed correction limits and cause permanent data loss.
3Productivity
If writing operations continue without interruption to maintain productivity, then writing performance is improved, but adjacent track data may be damaged
Solution Approach 1:
The patent replaces physical monitoring methods with signal-based evaluation. Instead of mechanically monitoring track conditions, the system uses positional error signals from the magnetic head to calculate damage amounts, enabling non-intrusive real-time assessment that doesn't interfere with writing operations unless necessary.
Solution Approach 2:
The patent introduces damage amount calculation as an intermediary between writing operations and protective operations. This intermediary evaluation layer processes positional error signals to determine when protective measures are needed, allowing writing to continue uninterrupted when safe and triggering protection only when actually necessary.
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
The solution effectively reduces the frequency of protection operations, enhancing write performance by accurately assessing signal quality and minimizing data loss, thus optimizing data protection and write speed.
Implementation Method 1
The magnetic head is configured to write data and read data to and from the magnetic disk
Implementation Method 2
read servo information when the magnetic head passes over each servo sector, acquire a positional error signal of the magnetic head based on the read servo information
Data Source
AI summary
A controller calculates, based on a positional error signal, an evaluation amount of damage on data of an adjacent track caused by a write operation, and compares a first amount being the evaluation amount with a first threshold value corresponding to a correction limit of an error correction in units of tracks. The controller interrupts the write operation in response to determining that the first amount is greater than the first threshold value. The controller executes a read operation on the adjacent track, acquires a metric representing a signal quality of the data of the adjacent track read by the read operation, calculates the evaluation amount based on the metric, and compares a second amount being the evaluation amount with the first threshold value. The controller continues the write operation in response to determining that the second amount is smaller than a first threshold value.