Data Block Refresh Threshold Management for Non-Volatile Memory

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Solution Overview

Problem

Non-volatile memory data blocks experience data retention issues due to frequent access, leading to potential data damage if not refreshed in time, as the electrical properties and continuous access affect charge storage, causing read disturbance and data corruption.

Innovation Solution

A method for managing data blocks involves reading valid data pages, updating access counts, determining if the access count exceeds a threshold, and moving data to a spare block when necessary, with the threshold adjusted based on erase counts to ensure timely refresh and prevent data damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If data blocks are frequently accessed to improve data access speed, then data access efficiency is improved, but data retention deteriorates due to read disturbance and electrical property degradation

Engineering Contradiction:

Improvedata access speedVSAvoiddata retention

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The system performs preliminary actions by monitoring access counts and erase counts to predict when data blocks will experience retention issues, and proactively refreshes them before actual data damage occurs. This prevents the harmful effect of read disturbance by moving data before the degradation becomes critical.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms by continuously tracking access counts and erase counts of data blocks, and using this information to dynamically adjust refresh thresholds and determine when data blocks need to be refreshed. This feedback loop enables adaptive management of data retention based on actual usage patterns.

Inventive Principle:

Principle #23Feedback

2Reliability

If data blocks are refreshed frequently to prevent data damage, then data retention is improved, but device complexity and operational overhead increase

Engineering Contradiction:

Improvedata retentionVSAvoidmanagement complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system changes parameters by dynamically adjusting the refresh threshold based on erase count. As the erase count increases, the refresh threshold is lowered, meaning data blocks are refreshed more frequently. This parameter adaptation allows the system to respond to degradation without requiring complex predictive models.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system enables self-service by allowing data blocks to effectively manage their own refresh needs through the access count and erase count tracking mechanism. Each data block's usage pattern is monitored, and refresh decisions are made based on its specific history, reducing the need for centralized complex management.

Inventive Principle:

Principle #25Self-service

3Reliability

If data blocks are refreshed timely to avoid data damage, then data reliability is improved, but access time is increased due to additional data movement operations

Engineering Contradiction:

Improvedata reliabilityVSAvoidrefresh time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system applies partial action by selectively refreshing only those data blocks that meet the refresh criteria (access count >= threshold and erase count >= erase threshold). Not all data blocks are refreshed uniformly, but only the ones that are at risk, thereby minimizing unnecessary data movement and time loss.

Inventive Principle:

Principle #16Partial or excessive action

4Ease of operation

If a fixed access count threshold is used to determine refresh timing, then ease of operation is improved, but manufacturing precision and adaptability deteriorate due to varying erase counts

Engineering Contradiction:

Improvethreshold management simplicityVSAvoidrefresh timing accuracy

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The system transitions from a static fixed threshold to a dynamic adaptive threshold that changes based on erase count. The refresh threshold is no longer a constant value but adapts to the actual wear state of the storage device, improving refresh timing accuracy while maintaining operational simplicity through automated adjustment.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10600491B2Method for managing data blocks and method of data management for data storage device

Publication Date: 2020.03.24 SILICON MOTION INC

AI summary

A method for managing a plurality of data blocks of a data storage device includes steps of: reading a plurality of data pages in the data blocks which having valid data; updating a plurality of access counts of the data pages in the data blocks; determining whether an access count of the data block is greater than or equal to an access count threshold, wherein the access count of the data block is selected from one of the access counts of the data pages therein; and when the determination is positive, storing data in the data block into a spare data block of the data blocks. The access count threshold is updated when an erase count of the data block is determined to be greater than or equal to an erase count threshold. A method of data management for a data storage device is also provided.