Disk Track Margin Control for Predicting Error Correction Limits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing disk devices face challenges in accurately predicting the correction limit for error sectors due to changes in bit error rates over time, leading to potential data loss from uncorrectable read errors.
Innovation Solution
The controller in the disk device updates track margin management information based on the bit error rate and reference values, improving the accuracy of correction limit prediction by adjusting the track margin coefficients dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error correction is performed on a per track basis, then error correction capability is provided, but prediction accuracy of correction limit deteriorates due to bit error rate changes over time
Solution Approach 1:
The patent applies dynamics by making the track margin management information adjustable and updateable. The controller dynamically adjusts track margin coefficients based on detected bit error rates, allowing the system to adapt to changing disk conditions over time. This resolves the contradiction by enabling the error correction system to maintain both its per-track capability and prediction accuracy through continuous adaptation.
Solution Approach 2:
The patent implements feedback by having the controller detect actual bit error rates during operation and use this information to update the track margin management information. The detected bit error rates feed back into the system to adjust the correction limit predictions, thereby maintaining prediction accuracy despite changes in disk performance over time.
2Device complexity
If track margin management information is fixed, then system simplicity is maintained, but prediction accuracy deteriorates due to changing bit error rates
Solution Approach 1:
The patent transitions from a static to a dynamic track margin management system. The controller automatically updates management information based on detected bit error rates, allowing the system to maintain simplicity in operation while achieving dynamic adaptation to changing conditions. This resolves the contradiction between simplicity and accuracy.
Solution Approach 2:
The system performs self-service by automatically detecting bit error rates and updating its own track margin management information without external intervention. The controller monitors its own performance and adjusts its correction limits accordingly, maintaining prediction accuracy while requiring minimal external management.
3Reliability
If correction limit is set conservatively, then data loss is prevented, but productivity decreases due to more frequent write retries
Solution Approach 1:
The patent applies dynamics by adjusting the correction limit dynamically based on actual disk conditions. When bit error rates are low, the system uses more aggressive correction limits to maximize productivity. When error rates increase, the system automatically reduces correction limits to prevent data loss. This dynamic adjustment resolves the contradiction between reliability and productivity.
Solution Approach 2:
The patent changes the parameter of correction limit based on detected bit error rates. The controller adjusts correction limit values as a function of actual error conditions, allowing the system to optimize both reliability and productivity. This parameter change enables the system to prevent data loss when needed while maintaining high write efficiency during normal operation.
Data Source
AI summary
According to one embodiment, in a disk device, a disk medium has a recording surface configured to face the head, the disk medium being medium where multiple tracks defined on the recording surface, each of the multiple tracks including multiple sectors. A controller is configured to perform error correction for each of the sectors on a per track basis. The controller is configured to predict, while writing data to a first track of the multiple tracks by a head, that the number of error sectors of a second track adjacent to the first track reaches a correction limit number of sectors, according to a track margin identified by first management information and an off-track amount of the first track. The controller is configured to update the first management information according to a bit error rate reference value and a bit error rate of information read from a track.