Read Disturb Detection in Solid State Storage
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Solution Overview
Problem
Existing read disturb detection techniques in solid state storage are inefficient, requiring excessive storage, time, and additional test reads, which can introduce more noise and impede host access.
Innovation Solution
Implementing a process that uses a subset of initial test pages to detect read disturb noise, where MSB pages are prioritized for testing, and a read counter system to optimize the detection process, allowing for fewer test reads and reduced noise introduction, with the option to test adjacent pages for faster detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing read disturb detection techniques are used to check all pages in a block, then detection coverage is complete, but storage requirements increase and detection time increases
Solution Approach 1:
The patent divides the block into multiple planes, with each plane containing multiple pages. Instead of checking all pages across all planes, the system selectively checks only certain pages in certain planes based on read count thresholds. This segmentation allows complete detection coverage of critical areas while reducing overall detection time and storage requirements.
Solution Approach 2:
The patent implements partial checking by monitoring read counts and only performing read disturb detection when thresholds are exceeded. Rather than checking all pages every time, the system performs detection only on specific pages in specific planes when necessary, reducing detection time while maintaining reliability for pages that actually need monitoring.
2Measurement precision
If read disturb detection is performed frequently on all pages, then detection accuracy improves, but noise introduction increases and host access is impeded
Solution Approach 1:
The patent implements periodic read disturb detection based on read count thresholds rather than continuous or frequent checking. The system monitors how many times pages have been read and only performs detection when predetermined thresholds are exceeded. This periodic approach maintains detection accuracy for pages that need it while minimizing noise introduction from unnecessary read operations.
Solution Approach 2:
The patent applies different detection strategies to different pages based on their characteristics and read patterns. Certain planes and pages are monitored more closely while others are checked less frequently or not at all. This localized quality approach ensures high detection accuracy for vulnerable pages while reducing overall noise introduction across the entire block.
3Productivity
If a read counter system is implemented to track read operations, then detection efficiency improves, but device complexity increases
Solution Approach 1:
The patent merges the read counter functionality with the existing page buffer and control logic. Instead of implementing separate complex counter management systems, the read count tracking is integrated into the existing memory controller architecture, combining multiple functions into unified structures that improve detection efficiency without proportionally increasing device complexity.
Data Source
AI summary
It is determined that a read count has reached one of a set of read count thresholds. An initial test page which corresponds to the read count threshold that has been reached is selected from a set of initial test pages. There is at least one page that is not in the set of initial test pages and is victimized by an offending page that also victimizes a page in the set of initial test pages. A test read is performed on the selected test page and the results of the test read of the selected test page are evaluated for read disturb noise.