Cluster-Level Refresh for Storage Device Error Correction
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Solution Overview
Problem
The late escaping cluster issue in storage devices occurs when error correction using a second correction code fails due to the accumulation of errors, leading to performance degradation and increased rewrite processing load, as existing solutions that refresh in units of large sizes, such as logical blocks, are inefficient.
Innovation Solution
A storage device that performs refresh operations in units of clusters, dynamically managing the correspondence between clusters and error correction codes within error correction groups, allowing for dynamic change in the destination of refreshed data and maintaining reliability by using a correction map to manage the relocation of data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refresh operation is performed in units of logical block, then data reliability is improved, but processing load and time consumption increase significantly
Solution Approach 1:
The patent segments the refresh operation from logical block level to cluster level. Instead of refreshing entire logical blocks, the system identifies and refreshes only specific clusters that contain errors, significantly reducing the refresh scope and time consumption while maintaining data reliability through targeted error correction.
Solution Approach 2:
The patent applies local quality by differentiating refresh strategies based on error characteristics. When a second correction code error is detected, only the specific cluster containing the error is refreshed, rather than applying uniform refresh to entire logical blocks. This localized approach reduces unnecessary processing while ensuring reliable correction where needed.
2Reliability
If refresh operation is performed in units of logical block, then data reliability is improved, but processing complexity increases
Solution Approach 1:
The patent divides the refresh process into segmented steps: error detection via first and second correction codes, identification of specific erroneous clusters, and targeted refresh of only those clusters. This segmentation simplifies the overall processing complexity compared to uniform logical block refresh, while maintaining reliability through systematic error handling.
Solution Approach 2:
The patent implements dynamic refresh decision-making based on error detection results. The system dynamically determines which clusters require refresh based on second correction code errors, adapting the refresh scope to actual error conditions rather than applying static uniform refresh to all logical blocks, thereby reducing processing complexity.
3Reliability
If error correction uses second correction code, then data reliability is improved, but late escaping cluster issues occur leading to performance degradation
Solution Approach 1:
The patent applies preliminary action by performing first correction code error detection and second correction code verification before finalizing data storage. This preliminary error detection and classification allows the system to identify clusters requiring refresh before they cause performance degradation, preventing late escaping cluster issues through proactive error management.
Solution Approach 2:
The patent implements feedback mechanisms where second correction code error detection provides information about clusters requiring refresh. This feedback loop enables the system to identify and correct errors that would otherwise escape detection, preventing performance degradation from late escaping clusters while maintaining high data reliability.
Data Source
AI summary
A storage device includes a non-volatile memory and a control circuit that reads data in units of cluster, and erase data in units of logical block which includes a plurality of clusters. Data in each cluster includes a first error correction code and each cluster is arranged in at least one error correction group, each including clusters and a second error correction code. The control circuit performs a refresh operation in units of cluster such that refresh target data in a cluster of a first logical block is moved to a cluster of a second logical block. A first error correction group related to the refresh target data includes the cluster of the first logical block before the moving, and the first error correction group related to the refresh target data includes a cluster of the first logical block and a cluster of the second logical block after the moving.