Open Block Management in Solid State Memory
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Solution Overview
Problem
In solid state memory, data in open blocks is susceptible to errors and corruption due to prolonged exposure, leading to potential data loss, as existing technologies lack efficient methods to differentiate and manage varying error sensitivities across pages within a block.
Innovation Solution
A circuit or module within the solid state memory system determines the error sensitivity of the last-written page in an open block, performing specific error mitigation procedures based on threshold comparisons to prevent data degradation, with different timeout periods and sensitivity adjustments applied depending on the page's susceptibility to errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error mitigation procedures are applied to all pages in open blocks, then data reliability is improved, but memory performance and longevity are degraded due to unnecessary refresh operations
Solution Approach 1:
The patent applies different error mitigation strategies to different pages within the same block based on their individual error sensitivity characteristics. Pages are classified into sensitivity groups (first, second, third groups) and each group receives appropriate mitigation procedures, avoiding uniform application to all pages and reducing unnecessary operations.
Solution Approach 2:
The patent changes the parameter of error sensitivity assessment by evaluating specific characteristics of the last-written page and using this assessment to dynamically adjust the error mitigation procedure applied. This allows the system to adapt the level of protection based on actual page conditions rather than applying fixed procedures.
2Reliability
If error mitigation procedures are applied to all pages in open blocks, then data loss is reduced, but memory longevity is degraded due to increased wear from unnecessary operations
Solution Approach 1:
The patent implements localized error mitigation by identifying pages with high error sensitivity (last-written pages) and applying protection procedures specifically to these pages while leaving other pages untreated. This selective approach prevents data loss in vulnerable pages without subjecting the entire block to wear-inducing operations.
Solution Approach 2:
The patent applies error mitigation procedures partially rather than universally - specifically to the last-written page or pages in the sensitivity group that requires protection. This partial action is sufficient to prevent data loss in vulnerable areas while avoiding excessive operations that would reduce memory longevity.
3Ease of manufacture
If uniform error mitigation is applied to all pages, then implementation simplicity is maintained, but efficiency is reduced due to inability to differentiate error sensitivities
Solution Approach 1:
The patent introduces local differentiation by classifying pages into sensitivity groups based on their error susceptibility characteristics. The last-written page is identified and evaluated for error sensitivity, and mitigation procedures are tailored to each group, improving efficiency without significantly complicating the implementation through systematic classification.
Solution Approach 2:
The patent segments the block's pages into different sensitivity groups (first, second, third groups) based on error susceptibility. This segmentation allows the system to apply appropriate mitigation procedures to each group, improving overall efficiency while maintaining manageable complexity through structured classification.
Data Source
AI summary
Systems and methods are disclosed for open block management. In certain embodiments, an apparatus may comprise a circuit configured to determine an error sensitivity of a last-written page of a block of a solid state memory that is in an open state where the block has not been fully filled with data. The error sensitivity may include a value that represents a susceptibility to developing data errors while in the open state. The circuit may perform a first error mitigation procedure when the error sensitivity is lower than a first threshold, include increasing an open block timeout period applied to the last-written page. The circuit may perform a second error mitigation procedure when the error sensitivity is higher than the first threshold, including copying data from the block to a new location when a first open block timeout is reached.