Nonvolatile Memory Refresh Control via Wear Leveling Segmentation

Solution Overview

Problem

Data storage devices with nonvolatile memory face challenges in maintaining data reliability and extending their lifespan due to the drift phenomenon, which causes state deterioration in memory cells, leading to potential read errors and reduced device performance over time.

Innovation Solution

Incorporating a reference memory region and a normal memory region within the data storage device, where a state monitor unit determines when to perform a refresh operation based on the reference memory region's state, and a controller manages wear leveling operations to identify regions that do not require refresh, thereby optimizing the refresh operation and extending the device's lifespan.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If refresh operations are performed on all normal memory regions, then data reliability is improved, but power consumption and time consumption increase

Engineering Contradiction:

Improvedata reliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies local quality by dividing the memory regions into different categories (first normal memory region subject to refresh, second normal memory region excluded from refresh) based on their wear leveling characteristics. This allows selective refresh operations only on regions that need them, rather than uniformly refreshing all regions, thereby reducing unnecessary power consumption while maintaining data reliability where required.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements partial action by performing refresh operations only on a portion of the normal memory regions (those excluded from wear leveling) rather than all regions. The controller determines which regions require refresh based on wear leveling operation data, applying refresh partially to the first normal memory region while excluding the second normal memory region, thus optimizing power usage.

Inventive Principle:

Principle #16Partial or excessive action

2Reliability

If refresh operations are performed on all normal memory regions, then data reliability is improved, but operation time increases

Engineering Contradiction:

Improvedata reliabilityVSAvoidoperation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies local quality by dividing the memory regions into different categories (first normal memory region subject to refresh, second normal memory region excluded from refresh) based on their wear leveling characteristics. This allows selective refresh operations only on regions that need them, rather than uniformly refreshing all regions, thereby reducing unnecessary operation time while maintaining data reliability where required.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements partial action by performing refresh operations only on a portion of the normal memory regions (those excluded from wear leveling) rather than all regions. The controller determines which regions require refresh based on wear leveling operation data, applying refresh partially to the first normal memory region while excluding the second normal memory region, thus optimizing operation time.

Inventive Principle:

Principle #16Partial or excessive action

3Duration of action of stationary object

If wear leveling operations are performed on all memory regions, then device lifespan is extended, but refresh operation efficiency decreases

Engineering Contradiction:

Improvedevice lifespanVSAvoidrefresh operation efficiency

Core Design Contradiction:

Duration of action of stationary objectVSProductivity

Solution Approach 1:

The patent applies segmentation by dividing the normal memory regions into two distinct groups: the first normal memory region that undergoes both wear leveling and refresh operations, and the second normal memory region that undergoes wear leveling but is excluded from refresh operations. This segmentation allows the system to optimize refresh operation efficiency by identifying and excluding regions that have already been protected by wear leveling, while still maintaining device lifespan through comprehensive wear leveling coverage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by dividing the memory regions into different categories (first normal memory region subject to refresh, second normal memory region excluded from refresh) based on their wear leveling characteristics. This allows selective refresh operations only on regions that need them, rather than uniformly refreshing all regions, thereby reducing unnecessary power consumption while maintaining data reliability where required.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS9966135B2Data storage device and operating method thereof

Publication Date: 2018.05.08 SK HYNIX INC

AI summary

A data storage device includes a nonvolatile memory device including a reference memory region and a normal memory region, and suitable for determining whether to perform a refresh operation, based on the reference memory region; and a controller suitable for determining a first memory region in the normal memory region based on wear leveling operation data, and controlling the nonvolatile memory device to perform the refresh operation for a second memory region excluding the first memory region in the normal memory region.