Adaptive LPSR Idle Interval Control for SSD NAND Wear Reduction

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Solution Overview

Problem

Existing low-power self-refresh (LPSR) mode in SSDs lacks control over idle intervals, leading to inefficient power management and accelerated NAND wear due to fixed timer settings that do not account for varying NAND power-cycle rates based on workload.

Innovation Solution

Adaptive control of LPSR idle intervals based on elapsed time, number of LPSR transitions, and other parameters to dynamically scale the interval, ensuring responsible consumption of NAND power-cycles and extending NAND longevity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a fixed timer interval is used for LPSR mode activation, then the implementation is simple, but power management efficiency deteriorates and NAND wear accelerates

Engineering Contradiction:

ImproveLPSR control mechanismVSAvoidpower management efficiency

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The LPSR idle interval is changed from a fixed static value to a dynamic value that adapts based on the current power-cycle consumption rate. The controller monitors the workload pattern and adjusts the idle interval accordingly, allowing the system to optimize power savings while preventing excessive NAND wear under varying workload conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system implements a feedback mechanism where the controller continuously monitors the power-cycle consumption rate and uses this information to adjust the LPSR idle interval. This closed-loop control ensures that the idle interval is optimized based on actual usage patterns, improving power management efficiency without requiring complex manual configuration

Inventive Principle:

Principle #23Feedback

2Device complexity

If a fixed timer interval is used for LPSR mode activation, then the implementation is simple, but NAND longevity deteriorates

Engineering Contradiction:

ImproveLPSR control mechanismVSAvoidNAND longevity

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The LPSR idle interval dynamically adapts to workload conditions, preventing excessively frequent transitions that would accelerate NAND wear. By adjusting the interval based on the power-cycle consumption rate, the system extends NAND longevity while maintaining simple control logic

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The controller proactively adjusts the LPSR idle interval based on predicted future power-cycle consumption patterns. By anticipating high-workload periods, the system can prevent excessive power-cycles before they occur, thereby protecting NAND longevity in advance

Inventive Principle:

Principle #10Preliminary action

3Loss of energy

If the LPSR idle interval is shortened to improve power savings, then energy consumption decreases, but NAND wear accelerates

Engineering Contradiction:

Improvepower consumptionVSAvoidNAND power-cycle lifespan

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The LPSR idle interval dynamically adjusts based on the current power-cycle consumption rate. When the consumption rate is high, the interval is lengthened to prevent excessive wear; when the consumption rate is low, the interval is shortened to maximize power savings, thus optimizing both energy efficiency and NAND longevity

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the idle interval parameter based on monitored workload characteristics and power-cycle consumption patterns. This parameter adaptation allows the system to achieve optimal power savings while maintaining NAND reliability across different operating conditions

Inventive Principle:

Principle #35Parameter changes

4Reliability

If the LPSR idle interval is extended to reduce power-cycles, then NAND longevity improves, but power management efficiency deteriorates

Engineering Contradiction:

ImproveNAND longevityVSAvoidpower management efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The LPSR idle interval dynamically adjusts to balance NAND longevity and power management efficiency. By monitoring the power-cycle consumption rate in real-time, the system can extend the interval when needed to protect NAND while maintaining efficient power management during normal operating conditions

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9959042B2Robust mechanism for adaptive power conservation in solid-state devices

Publication Date: 2018.05.01 APPLE INC

AI summary

Disclosed herein is a technique for dynamically scaling a low-power self-refresh (LPSR) idle interval associated with a solid state drive (SSD) of a user device in order to promote enhanced battery life efficiency within the user device. A determination can be made regarding whether the LPSR idle interval is to be scaled up or scaled down. Specifically, the determination is based on a total elapsed since the user device was first powered on and a total number of LPSR transitions or cycles that have been performed in association with the SSD. In turn, the dynamic scaling of the LPSR idle intervals causes NAND power-cycles to be consumed responsibly over an average system lifetime of the user device, which can result in better power management at the user device.