SAS Expander Power Saving Mode Cable Type Detection

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Solution Overview

Problem

SAS expanders face a deadlock state when an SAS cable is cold-swapped from a Copper cable to an AOC cable after entering consumption-power saving mode, as they cannot change settings and fail to receive activation interruption packets, preventing the restoration of power supply.

Innovation Solution

A control device with a power supply controller, detector, and setting changer that shifts power to a consumption-power saving mode and detects cable changes, obtaining cable type information to adjust settings accordingly, ensuring correct settings for different cable types even during power saving mode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the SAS expander enters consumption-power saving mode to reduce power consumption, then power saving is improved, but the ability to detect and respond to cable type changes is lost, causing deadlock

Engineering Contradiction:

Improvepower consumptionVSAvoidability to respond to cable type changes

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The system performs preliminary detection of cable type changes by monitoring link status transitions (link-down followed by link-up) even while in power-saving mode. This preliminary action allows the system to prepare for upcoming cable type changes without fully activating, thus maintaining low power consumption while still detecting changes that require adaptation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary detection mechanism that uses link status transitions as a mediator to indirectly detect cable type changes. Instead of directly monitoring cable type (which would require full activation), the system uses link-down/link-up events as intermediate signals that indicate a cable replacement has occurred, allowing detection without full system activation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the SAS expander maintains full operational status to detect cable type changes, then adaptability is improved, but power consumption increases

Engineering Contradiction:

Improveability to detect cable type changesVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent extracts the essential detection function from the full operational status. Instead of maintaining complete system readiness, it isolates and maintains only the minimal necessary functionality (link status monitoring) required to detect cable type changes, while keeping other functions in low-power state. This extraction allows detection capability without the overhead of full operational status.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system performs partial action by monitoring only link status transitions rather than continuously analyzing all operational parameters. This partial monitoring provides sufficient information to detect cable type changes while consuming significantly less power than full system operation would require.

Inventive Principle:

Principle #16Partial or excessive action

3Ease of operation

If the SAS expander uses Wake on SAS function to enable automatic power restoration, then ease of operation is improved, but reliability deteriorates when cable type changes occur in power-saving mode

Engineering Contradiction:

Improveautomatic power restorationVSAvoidpower supply restoration reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent introduces feedback by continuously monitoring link status transitions and using this information to trigger setting changes. The feedback loop detects cable type changes through link-down/link-up events and automatically initiates the appropriate response (setting reconfiguration and power restoration), ensuring reliable operation even in power-saving mode without requiring manual intervention.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary detection of cable type changes before full power restoration is needed. By detecting link status transitions early, the system can prepare appropriate settings in advance, ensuring that when power restoration occurs, the correct configurations are already in place, thus improving reliability of the Wake on SAS function.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10372186B2Control device and computer-readable recording medium having stored therein control program

Publication Date: 2019.08.06 FUJITSU LTD

AI summary

A control device includes a controller that controls a target device, and the controller includes a power supply controller, a detector, an obtainer, and a setting changer. The power supply controller shifts, when a port connected to another device via a cable comes into an unused state, a power supply mode to the target device and to the control device from a normal power supply mode into a power saving mode capable of receiving activation interruption. The obtainer obtains, when the detector detects the change in the mounting state of the cable, type information representing a type of the cable. The setting changer that changes setting of the cable in accordance with the type information obtained by the obtainer. This makes it possible to be surely restored to the normal power supply mode even when a cable is replaced with another type of cable in a power saving mode.