Flash Memory Block Probe Triggering via Disturbance State Tracking
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Solution Overview
Problem
Flash memory devices face data retention issues and disturbance effects such as erase disturb, program disturb, and read disturb, which compromise data reliability over time.
Innovation Solution
A control method for a storage device that includes a memory controller and flash memory, where the controller maintains a state table to track disturbance counts and last check times for each block, triggering a probe operation when the disturbance count exceeds a threshold or a predetermined time has elapsed since the last check, to enhance data reliability by identifying and mitigating potential data loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous probe operations are performed on all blocks, then data reliability is improved, but device complexity and energy consumption increase
Solution Approach 1:
The patent applies local quality by differentiating probe operation strategies for different blocks based on their individual disturbance counts and last check times. Instead of uniform probing, the system selectively probes only those blocks that meet specific criteria (disturbance count >= threshold OR elapsed time >= threshold), thereby reducing overall system complexity while maintaining data reliability where needed.
Solution Approach 2:
The patent maintains a state table that pre-records disturbance counts and last check times for all blocks before probe operations are triggered. This preliminary tracking allows the system to proactively identify blocks requiring probe operations based on predetermined thresholds, rather than reactively probing all blocks after issues occur, thus reducing control complexity.
2Reliability
If frequent probe operations are triggered, then data reliability is improved, but energy consumption increases
Solution Approach 1:
The patent implements partial action by triggering probe operations only on specific blocks that meet predetermined criteria (disturbance count >= threshold OR elapsed time >= threshold), rather than performing exhaustive probing on all blocks. This selective approach maintains data reliability for at-risk blocks while significantly reducing overall energy consumption.
Solution Approach 2:
The state table pre-tracks disturbance counts and last check times, allowing the system to identify probe candidates before actually performing probe operations. This preliminary identification based on thresholds prevents unnecessary energy expenditure on blocks that do not require probing.
3Use of energy by moving object
If probe operations are delayed, then energy consumption is reduced, but data retention problems worsen
Solution Approach 1:
The system performs preliminary tracking of both disturbance counts and elapsed times in the state table. Probe operations are triggered when either criterion is met, ensuring that data retention issues are addressed promptly when they become significant, while avoiding unnecessary early probing that would waste energy.
Solution Approach 2:
The patent employs dynamic thresholds for disturbance count and elapsed time that can be adjusted based on block characteristics and operational conditions. This dynamic approach allows the system to optimize the timing of probe operations, triggering them early enough to prevent data retention problems while delaying them long enough to conserve energy.
Data Source
AI summary
A control method for a storage device is provided. The storage device includes a memory controller and a flash memory. The flash memory includes multiple blocks. The control method includes the following steps. Maintain a state table by the memory controller, wherein the state table records a disturbance count and a last check time of the blocks in the flash memory. Trigger a probe operation on a target block in the flash memory when at least one of the following conditions is met: (a) the disturbance count of the target block is greater than or equal to a disturbance count threshold; and (b) an elapsed time period of the target block is greater than or equal to an elapsed time threshold, wherein the elapsed time period of the target block starts from the last check time of the target block.