Probation Bit for SSD Erasure Block Error Tracking
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Solution Overview
Problem
Solid state drives (SSDs) face inefficiencies in tracking and managing erasure blocks, leading to mismatches in metadata structures, which can prolong garbage collection operations and impact performance, especially when uncorrected read and write errors occur, requiring a more efficient mechanism to evaluate and recertify erasure blocks.
Innovation Solution
Implementing a counter to track the number of read recovery operations for erasure blocks, comparing it to the program/erase count, and deallocating blocks if the error count exceeds a certain percentage, thereby identifying and removing defective blocks from service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a counter is implemented to track read recovery operations for erasure blocks, then the accuracy of garbage collection operations is improved, but the device complexity increases
Solution Approach 1:
A monitor module is introduced as an intermediary component that tracks read recovery operations and manages the counter for each erasure block. This intermediary handles the complexity of error tracking and garbage collection decision-making, allowing the main SSD controller to focus on core data management functions while achieving improved garbage collection accuracy through systematic monitoring and counting mechanisms
2Reliability
If defective erasure blocks are proactively identified and removed from service, then the reliability of the SSD is improved, but the productivity decreases due to additional overhead operations
Solution Approach 1:
The system performs preliminary tracking of read recovery operations and proactively identifies defective erasure blocks before they cause data integrity issues. By maintaining counters that track the number of read recovery operations for each erasure block and comparing them against thresholds, the system removes problematic blocks from service in advance, preventing future failures while managing the overhead through efficient counter management and threshold-based decision-making
Data Source
AI summary
A data storage system can receive a data write request to write data to a physical address of a non-volatile semiconductor memory prior to detecting an error while storing the write data to the physical address. The detected error is corrected with a monitor module connected to the non-volatile semiconductor memory and a counter associated with the physical address is incremented with the monitor module in response to the corrected error. The write data can be subsequently read to a host in response to a data read request.