Forced Sync Mark Recovery for Defect-Tolerant Data Reads
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Solution Overview
Problem
Existing systems for identifying a reproducible location on a storage medium, such as a hard disk, often fail to detect data sync patterns due to media defects, leading to costly retries and potential data loss, as they are not capable of identifying the data sync mark effectively.
Innovation Solution
The implementation of a circuit that uses a data storage circuit, pattern comparison circuit, and threshold comparison circuit to identify a reproducible location based on waveform correlation, employing a forced data sync mark that is placed at a defined distance from a media defect or anomaly, allowing for reliable data recovery even when the original sync mark is undetectable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional data sync pattern search approaches are used, then the system can identify sync marks under normal conditions, but the system fails to identify sync marks when media defects are present, leading to data loss
Solution Approach 1:
The system performs preliminary actions by storing multiple sets of data samples from different reads before attempting to identify the sync mark. When a sync mark is missed due to media defects, the system has pre-stored alternative data samples ready for comparison, enabling recovery without losing the data sector.
Solution Approach 2:
The system creates copies of data samples from multiple reads and stores them in memory. Instead of relying on a single read operation, the system maintains multiple copies of the same data region, allowing it to compare and identify the correct sync mark location even when one or more reads are corrupted by media defects.
2Reliability
If retry mechanisms are implemented to recover from missed sync marks, then data loss can be prevented, but the circuit complexity and processing time increase significantly
Solution Approach 1:
The system performs preliminary actions by pre-storing multiple sets of data samples from different reads in memory before the sync mark identification process. This eliminates the need for complex retry mechanisms during operation, as the alternative data samples are already prepared and readily available for immediate comparison.
Solution Approach 2:
The system uses its own previously read and stored data samples to recover from sync mark identification failures. By comparing currently received data with previously stored data samples, the system performs self-service recovery without requiring external intervention or complex additional circuitry.
3Reliability
If multiple search approaches are used to identify the data sync pattern, then the probability of successful identification increases, but the processing time and computational cost increase
Solution Approach 1:
The system uses copies of data samples from previous reads to rapidly compare against current data. By maintaining multiple copies in memory and performing parallel comparisons, the system achieves high identification success rates without the time penalty of sequential retry operations, as all comparison data is already available in memory.
Solution Approach 2:
The system performs the time-consuming data acquisition and storage actions in advance, before the sync mark identification is needed. By pre-storing multiple data samples during normal operation, the system eliminates the need for time-consuming re-reading during retry scenarios, significantly reducing processing time while maintaining high success rates.
Data Source
AI summary
Various embodiments of the present invention provide systems and methods for identifying a reproducible location on a storage medium. As an example, a circuit is discussed that includes a data storage circuit, a pattern comparison circuit, and a threshold comparison circuit. The data storage circuit is operable to store a first set of data samples corresponding to a region of interest. The pattern comparison circuit is operable to compare a subset of the first set of data samples with a subset of a second set of data samples corresponding to the region of interest. The pattern comparison circuit is operable to yield a match value corresponding to a degree of similarity between the first set of data samples with the subset of a second set of data samples. The threshold comparison circuit is operable to indicate an anchor point based at least in part on the magnitude of the match value relative to a threshold value.