Dynamic Wear Leveling Using Read Error Feedback in Virtual Blocks
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Solution Overview
Problem
Conventional dynamic wear leveling techniques fail to account for read errors, leading to uneven wear distribution among virtual blocks in memory devices, resulting in premature retirement and reduced device lifetime.
Innovation Solution
A controller monitors program/erase cycles and collects read errors to generate error profiles, dynamically selecting healthy virtual blocks for data storage while retiring unhealthy blocks, thus balancing wear across the memory device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dynamic wear leveling techniques are used to balance P/E cycles across virtual blocks, then wear distribution is improved, but read errors are not accounted for leading to premature retirement of healthy blocks
Solution Approach 1:
The system implements feedback by continuously monitoring read errors from virtual blocks and using this information to adjust block selection decisions. The controller tracks read error counts for each virtual block and incorporates this feedback into the wear leveling algorithm, allowing it to identify and avoid unhealthy blocks that would otherwise be selected based solely on P/E cycle counts.
Solution Approach 2:
The system changes the selection criteria parameter from considering only P/E cycle counts to considering both P/E cycle counts and read error counts. This parameter change allows the wear leveling algorithm to differentiate between healthy blocks with high P/E cycles and unhealthy blocks with low P/E cycles but high error rates, thereby improving block selection accuracy and extending device lifetime.
2Stability of the object's composition
If virtual blocks with low P/E cycles are preferentially selected for writing, then wear distribution is improved, but healthy blocks may be retired prematurely due to unmonitored read errors
Solution Approach 1:
The system uses feedback from read error monitoring to correct the wear leveling process. By continuously tracking read errors and incorporating this information into block selection, the system prevents premature retirement of healthy blocks while maintaining uniform wear distribution across the memory device.
Solution Approach 2:
The system performs preliminary monitoring of read errors for each virtual block before making selection decisions. This preliminary action allows the wear leveling algorithm to identify potentially unhealthy blocks in advance and adjust selection criteria accordingly, preventing premature retirement while maintaining wear distribution uniformity.
3Reliability
If read error monitoring is added to conventional wear leveling, then block selection accuracy is improved, but system complexity increases
Solution Approach 1:
The system achieves multi-functionality by using the existing read error monitoring infrastructure for dual purposes: traditional error correction and wear leveling decision-making. The same read error data that is collected for error correction is also utilized for block health assessment and wear leveling, eliminating the need for separate monitoring systems and reducing overall complexity.
Solution Approach 2:
The wear leveling system serves itself by utilizing read error information that is already being collected and processed by the memory controller for error correction purposes. This self-service approach allows the system to improve block selection accuracy without adding dedicated monitoring hardware or complex external control mechanisms.
Data Source
AI summary
A data storage system may include a memory device and a controller. The memory device may include a plurality of virtual blocks. The controller may include at least one processor and a memory. The memory may include instructions stored thereon, that when that when executed by the at least one processor, cause the at least one processor to: monitor a number of program/erase cycles for the plurality of virtual blocks; collect read errors for the plurality of virtual blocks; select a virtual block of the plurality of virtual blocks to open based on the number of program/erase cycles and the collected read errors; and write data to the selected open virtual block.