Magnetic Disk Refresh via Detection Area Error Rate Monitoring
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Solution Overview
Problem
Magnetic disk devices face challenges in detecting and addressing data degradation caused by thermal fluctuations, particularly after sudden power loss, as they need to read all data to evaluate degradation, making the process time-consuming and inefficient when large quantities of data are stored.
Innovation Solution
The magnetic disk device includes a detection area where data patterns susceptible to thermal fluctuations are written, allowing for the measurement of signal quality and error rates of detection data, which are then used to predict and correct the error rates of normal data, facilitating a refresh process before significant degradation occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the magnetic disk device reads all data to detect thermal fluctuation degradation, then detection reliability is improved, but processing time increases significantly
Solution Approach 1:
The patent divides the data storage space into a detection area (containing detection data with patterns susceptible to thermal fluctuations) and a normal data area. By segmenting the data and only reading the detection area to assess thermal fluctuation effects, the system achieves reliable detection without the time penalty of reading all data.
Solution Approach 2:
The patent introduces detection data as an intermediary element that serves as a proxy for monitoring thermal fluctuation effects. This detection data acts as a sentinel or indicator that reflects the state of normal data without requiring direct examination of all normal data, thereby reducing processing time while maintaining detection reliability.
2Reliability
If the magnetic disk device reads all data after sudden power loss, then data degradation detection is thorough, but the refresh process becomes inefficient
Solution Approach 1:
The patent performs preliminary action by writing detection data with specific patterns known to be susceptible to thermal fluctuations before normal operation. After sudden power loss, this pre-positioned detection data enables immediate assessment of thermal damage without needing to examine all data, thus maintaining thorough detection while improving refresh efficiency.
Solution Approach 2:
The patent creates a copy or representation of potential data degradation patterns through detection data. This detection data serves as a model or surrogate that mimics how normal data would be affected by thermal fluctuations, allowing the system to predict degradation without examining actual normal data.
3Object-affected harmful factors
If detection data with low frequency patterns is used, then thermal fluctuation susceptibility is increased, but the distinction from normal data becomes more difficult
Solution Approach 1:
The patent applies local quality by creating detection data with specific low-frequency patterns only in the detection area, while normal data maintains its typical pattern distribution. This localized differentiation allows the detection area to be highly susceptible to thermal fluctuations while remaining distinguishable from normal data areas through pattern analysis.
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 enables efficient detection and correction of data degradation due to thermal fluctuations, improving data reliability by allowing the device to measure signal quality of detection data without reading all normal data, thus preventing read errors and enhancing storage reliability.
Implementation Method 1
a head that writes data to the disk and reads data from the disk
Implementation Method 2
When a magnetic disk device is exposed to thermal fluctuations, such as a high temperature environment, data stored in the disk device may be corrupted or otherwise degraded
Data Source
AI summary
According to one embodiment, a magnetic disk device includes a disk, a head that writes data to the disk and reads data from the disk, and a controller. The controller is configured to read first data written on the disk, measure a first read error rate of the first data, determine a difference in the first read error rate from a previously determined read error rate of the first data, determine a current read error rate for second data written on the disk based on the difference in the first read error rate from the previously determined read error rate, and determine whether a refresh process is performed on the second data based on the current error rate.