Flash Memory Declared Capacity Reduction for Wear Management

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Current storage systems face challenges in managing and utilizing the extended capacity of flash memory devices beyond their wear limits, as existing mechanisms are inadequate for adjusting operations when the capacity decreases, leading to potential data loss and system inefficiencies.

Innovation Solution

The implementation of a system and method to detect trigger conditions in flash memory devices, allowing for the reduction of declared capacity by enabling an amelioration process that adjusts the storage device's operation, such as changing the encoding format from multi-level to single-level, to extend the device's lifespan and maintain data integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If flash memory devices continue to be used beyond wear limits, then operational life is extended, but data integrity and reliability deteriorate

Engineering Contradiction:
Improveoperational lifeVSAvoiddata integrity
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The system dynamically adjusts the declared capacity of flash memory devices based on real-time wear metrics. When wear thresholds are exceeded, the system automatically reduces the available capacity rather than marking the device as failed, allowing continued operation with reduced but reliable storage space. This dynamic adaptation resolves the contradiction by enabling extended operational life while maintaining data integrity through capacity adjustment.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the operational parameters of flash memory devices by modifying the declared capacity parameter in response to wear conditions. When wear metrics indicate degraded performance, the system alters the capacity parameter to reflect only the reliable portion of storage, allowing the device to continue operating reliably with reduced capacity rather than failing completely.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If declared capacity is reduced to maintain reliability, then data integrity is preserved, but storage utilization decreases

Engineering Contradiction:
Improvedata integrityVSAvoidstorage utilization
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

Instead of completely disabling storage devices that exceed wear limits, the system applies partial action by reducing the declared capacity to only the reliable portion. This allows continued utilization of the storage device at a reduced level rather than completely abandoning it, resolving the contradiction between maintaining data integrity and preserving storage utilization.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The system converts the harmful effect of wear degradation into a beneficial outcome by using wear metrics to dynamically adjust capacity. Rather than allowing wear to cause data corruption, the system proactively reduces capacity based on wear thresholds, turning the potential harm into a mechanism for maintaining reliability while preserving partial utilization.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Duration of action of stationary object

If wear-leveling technology distributes wear across portions, then device lifespan is extended, but the entire device fails when any portion reaches wear limit

Engineering Contradiction:
Improvedevice lifespanVSAvoiddevice failure condition
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The system segments the storage device into multiple portions and independently manages the declared capacity of each portion based on its individual wear metrics. When one portion reaches wear limits, only that portion's capacity is reduced, while other portions continue to operate at full capacity. This segmentation resolves the contradiction by allowing extended device lifespan while preventing complete device failure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention applies local quality by treating different portions of the storage device differently based on their individual wear conditions. Each portion's declared capacity is independently adjusted according to its specific wear metrics, allowing healthy portions to maintain full capacity while degraded portions are reduced. This resolves the all-or-nothing failure mode of traditional wear-leveling.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3189438B1Triggering a process to reduce declared capacity of a storage device in a multi-storage-device storage system
Publication Date: 2022.06.01 SANDISK TECHNOLOGIES LLC
  • EP3189438B1 patent drawingFigure 1A
  • EP3189438B1 patent drawingFigure 1B
  • EP3189438B1 patent drawingFigure 1C

AI summary

Systems, methods and/or devices are used to enable triggering a process to reduce declared capacity of a storage device in a multi-storage-device storage system. In one aspect, the method includes: (1) obtaining, for each storage device of a plurality of storage devices of the storage system, one or more metrics of the storage device, the storage device including non- volatile memory, (2) detecting a trigger condition for reducing declared capacity of the non-volatile memory of a respective storage device of the plurality of storage devices, the trigger condition detected in accordance with the one or more metrics of one or more storage devices, and (3) enabling an amelioration process associated with the detected trigger condition, the amelioration process to reduce declared capacity of the non-volatile memory of the respective storage device. In some embodiments, the respective storage device includes one or more flash memory devices.