Quick Reliability Scan for Memory Device Blocks
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Solution Overview
Problem
Full media scans for memory devices are excessively time-consuming, making them impractical for ensuring data retention and reliability, especially in scenarios like short power-on usage, long power-off usage, and large cross-temperature usage cases, where they fail to prevent data loss and ensure correct data retrieval.
Innovation Solution
A quick reliability scan method that scans only a subset of pages in each block, deferring block folding until after the scan is complete, allowing for concurrent initiation with a full media scan, thereby reducing the overall time required and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a full media scan is performed on all blocks and pages of a memory device, then data retention and reliability are ensured, but the scan time becomes excessively long and impractical
Solution Approach 1:
The patent divides the memory device into multiple blocks and further divides each block into multiple pages. Instead of scanning all pages in all blocks sequentially, the method scans only a subset of pages from each block during an initial quick scan phase. This segmentation approach allows the reliability assessment to be performed on representative samples rather than the entire memory space, significantly reducing scan time while maintaining reliability detection capability.
Solution Approach 2:
The patent implements a two-phase scanning approach where a partial scan (quick scan) is performed first on a subset of pages to quickly identify potentially unreliable blocks. Only blocks that fail the quick scan criteria undergo a full scan of all their pages. This partial action strategy avoids the excessive time cost of scanning every page in every block while still ensuring reliability by thoroughly examining suspicious blocks.
2Reliability
If block folding is performed immediately upon detecting unreliable pages during a scan, then data loss is prevented, but the scan process is interrupted and cannot complete the full assessment
Solution Approach 1:
The patent performs preliminary identification of unreliable blocks through quick scanning of page subsets before executing the actual folding operation. During the quick scan phase, blocks are marked as candidates for folding based on error thresholds, but the folding itself is deferred until after the quick scan completes. This preliminary identification allows the scan process to finish assessing all candidate blocks before any data relocation occurs, maintaining both reliability and scan productivity.
3Loss of time
If a quick scan of only a subset of pages is performed, then scan time is reduced, but the ability to detect all unreliable blocks may be compromised
Solution Approach 1:
The patent implements a feedback mechanism where the results of quick scans on page subsets are used to identify candidate blocks that require further investigation. Blocks exceeding error thresholds during quick scanning trigger a feedback loop that initiates full scans of those specific blocks. This feedback-driven approach ensures that while the initial quick scan uses sampling to save time, any blocks showing reliability issues are thoroughly re-examined, maintaining high detection accuracy.
Solution Approach 2:
The patent replaces the mechanical approach of uniformly scanning every page with a smarter, adaptive system that uses statistical sampling and threshold-based filtering. Instead of treating all pages equally, the system substitutes a two-stage process: first using quick scans with error threshold comparisons to filter out reliable blocks, then applying full scans only to suspect blocks. This substitution maintains measurement precision while dramatically reducing overall scan time.
Data Source
AI summary
Technologies for performing a quick reliability scan include, for a particular block of a set of blocks of different block types, each block of the set of blocks including pages of memory of a physical memory device, identifying subset of the pages of the block. The block is scanned by scanning the subset of the plurality of pages of the block for a fold condition. A page of the subset of the plurality of pages is determined to have the fold condition. After the set of blocks has been scanned, the folding of the block that includes the page that has been determined to have the fold condition is requested.