Failed Sector Data Recovery Using Reader Offset Estimation
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Solution Overview
Problem
Current data recovery methods in data storage devices often fail to effectively read data from failed sectors due to misalignment and errors, leading to incomplete or unsuccessful recovery, as they typically rely on individual recovery schemes that reset parameters and do not combine recovery processes effectively.
Innovation Solution
A composite data recovery procedure that estimates a reader offset position based on position error signals, replaces channel parameters, and performs iterative outer code recovery, combining multiple reads and interference removal to enhance data recovery efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual recovery schemes are used with parameter resets, then the recovery process is simple to implement, but data recovery effectiveness is incomplete or unsuccessful
Solution Approach 1:
The patent combines multiple individual recovery schemes (reader offset estimation, channel parameter replacement, iterative outer code recovery) into a single composite recovery procedure. This integration allows the system to maintain simplicity while achieving complete data recovery from failed sectors, as the schemes work together in a coordinated manner rather than independently.
2Measurement precision
If reader offset position is estimated and multiple reads are performed, then reading accuracy is improved, but recovery time increases
Solution Approach 1:
The patent performs reader offset position estimation and channel parameter replacement before the actual data reading process. By preparing these parameters in advance based on position error signals from initial read attempts, the system ensures accurate reading from the first attempt, thereby improving reading accuracy without significantly increasing overall recovery time.
3Reliability
If iterative outer code recovery is performed, then data recovery completeness is improved, but processing complexity increases
Solution Approach 1:
The patent implements iterative outer code recovery where the output of each decoding iteration feeds back into the next iteration. This feedback mechanism allows the system to progressively improve data recovery completeness by using information from previous iterations, while the iterative process is managed in a controlled manner to avoid excessive complexity.
4Measurement precision
If interference removal is performed from adjacent tracks, then signal purity is improved, but processing time increases
Solution Approach 1:
The patent extracts and removes interference signals from adjacent tracks during the data recovery process. By specifically targeting and eliminating this interference, the system improves signal purity and reading accuracy. The interference removal is integrated into the overall recovery procedure to minimize additional processing time.
Data Source
AI summary
A method of recovering data from one or more failed data sectors includes estimating a reader offset position from a first or a second read attempt of the one or more failed data sectors at a current set of channel parameters and basing the estimated reader offset position on, at least in part, a position error signal generated during the first or second read attempt. At least one read is performed on the one or more failed data sectors at the estimated reader offset position to obtain one or more samples. The one or more samples are processed to obtain a processed sample. Iterative outer code recovery is performed on the processed sample.