SSD Power Loss Protection via PSU Pre-Warning Signals

Solution Overview

Problem

Solid-state storage devices (SSDs) face challenges in protecting data due to the degradation of internal power loss protection (PLP) circuits, which may fail to prevent data loss during power loss events, especially when bulk capacitors are damaged, and existing systems rely on detecting input voltage variances after the fact.

Innovation Solution

A method and system that utilize pre-warning signals from a power supply unit to trigger power loss protection actions in SSDs before the event is detectable, allowing them to switch to hold-up energy and flush write queues to persistent memory, thereby preventing data loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If internal power loss protection circuits with bulk capacitors are used in SSDs, then data protection during power loss events is improved, but the circuits degrade over time and may fail to protect data when capacitors are damaged

Engineering Contradiction:

Improvedata protection capabilityVSAvoidcircuit lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The power supply unit performs preliminary detection of power loss conditions and issues warnings to SSDs before the actual power loss occurs. This allows SSDs to proactively initiate data protection actions (flushing write queues to persistent memory) using available hold-up energy, rather than waiting for the PLP circuit to detect power loss after the capacitors have already degraded or failed.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If SSDs wait for power loss detection by their own PLP circuit, then the detection is reliable, but the detection occurs after the power loss event has already happened

Engineering Contradiction:

Improvepower loss detection accuracyVSAvoidresponse time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The power supply unit performs preliminary detection of power loss conditions and issues warnings to SSDs before the actual power loss occurs. This allows SSDs to proactively initiate data protection actions (flushing write queues to persistent memory) using available hold-up energy, rather than waiting for the PLP circuit to detect power loss after the capacitors have already degraded or failed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The power supply unit acts as an intermediary between the power source and the SSDs. It monitors power conditions and communicates warnings to SSDs before power loss occurs, enabling earlier response than the SSDs' own PLP circuits could achieve alone.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If SSDs have robust PLP circuit capabilities to ensure data protection, then data integrity is improved, but the cost and device complexity increase

Engineering Contradiction:

Improvedata integrityVSAvoidPLP circuit capabilities

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The power supply unit performs preliminary detection of power loss conditions and issues warnings to SSDs before the actual power loss occurs. This allows SSDs to proactively initiate data protection actions (flushing write queues to persistent memory) using available hold-up energy, rather than waiting for the PLP circuit to detect power loss after the capacitors have already degraded or failed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The power supply unit provides the warning signal that enables SSDs to self-protect their data without requiring excessively robust PLP circuits. The SSDs use their own hold-up energy resources to complete protection actions when warned, reducing dependence on complex external protection circuitry.

Inventive Principle:

Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach provides additional hold-up time for SSDs to complete protective actions before depletion of hold-up energy, reducing the need for extensive PLP circuit capabilities and costs, and ensuring data integrity even if local PLP capacitors degrade or fail.

Implementation Method 1

These circuits, which typically rely on bulk capacitors, can degrade over the time

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS10599503B2Triggering power loss protection on solid-state storage devices

Publication Date: 2020.03.24 DELL PROD LP

AI summary

An information handling system may implement techniques for triggering power loss protection on solid-state storage devices (SSDs) based on PSU pre-warning signals (such as de-asserted POK or VIN_GOOD signals) indicating that power loss is imminent. The pre-warning signals may be provided directly to SSDs over a dedicated connection or may be passed through other components of the information handling system (such as power loss warning logic, a platform controller hub, or a CPU) to a storage controller. The pre-warning signal may be provided to the storage controller as a power loss warning interrupt. This interrupt may cause the storage system controller to issue an in-band message/command to the SSDs or to provide a signal on a dedicated connection to the SSDs in order to trigger power loss protection actions on the SSDs, including switching their power sources and flushing write queues before available hold-up energy is depleted.