SAS Expander Virtual Device Manager for Host Driver Communication

Solution Overview

Problem

In SAS protocol-based systems, there is a need for host device drivers to communicate with each other over a SAS fabric, especially in environments with dual controllers or RAID technology, where traditional configurations limit visibility and communication between drivers residing on different hosts.

Innovation Solution

The implementation of a SAS expander with a virtual device manager and communications manager that generates virtual device tables and PHYs, allowing host device drivers to communicate by operating as targets and establishing connections without requiring separate communication links or protocols like Ethernet, using virtual device PHYs to facilitate data exchange and access control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional SAS configurations are used, then device connectivity is maintained, but driver visibility and communication capability between hosts are limited

Engineering Contradiction:

Improvedriver communication capabilityVSAvoidcommunication configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The SAS expander acts as an intermediary device between host initiators and target devices. It includes a virtual device manager that creates virtual device PHYs representing host device drivers, and a communications manager that establishes connections between initiators and virtual devices. This mediator enables driver-to-driver communication over the SAS fabric without requiring direct peer-to-peer connections or separate communication protocols like Ethernet.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The SAS expander performs multiple functions: it manages traditional SAS target device connections, creates virtual device representations of host drivers, establishes communication pathways between initiators and virtual devices, and maintains access control. This multi-functionality consolidates what would otherwise require separate communication infrastructure into a single device.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If separate communication links like Ethernet are used for driver communication, then communication reliability is improved, but device complexity and infrastructure requirements increase

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidcommunication infrastructure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The SAS expander performs multiple functions: it manages traditional SAS target device connections, creates virtual device representations of host drivers, establishes communication pathways between initiators and virtual devices, and maintains access control. This multi-functionality consolidates what would otherwise require separate communication infrastructure into a single device.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges driver communication functionality with the existing SAS fabric infrastructure. By representing host drivers as virtual devices within the SAS expander, the system combines driver-to-driver communication with traditional storage device communication over the same physical and logical infrastructure, eliminating the need for separate Ethernet or other communication links.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If direct point-to-point connections are established between initiators and target devices, then connection simplicity is maintained, but scalability for multiple initiators and targets is limited

Engineering Contradiction:

Improvemulti-initiator multi-target connectivityVSAvoidconnection management

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The SAS expander segments the communication function into distinct components: a virtual device manager that handles virtual device creation and mapping, and a communications manager that handles connection establishment and maintenance. This segmentation allows the system to manage complex multi-initiator, multi-target connections systematically through structured processes rather than monolithic connection management.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The SAS expander acts as an intermediary device between host initiators and target devices. It includes a virtual device manager that creates virtual device PHYs representing host device drivers, and a communications manager that establishes connections between initiators and virtual devices. This mediator enables driver-to-driver communication over the SAS fabric without requiring direct peer-to-peer connections or separate communication protocols like Ethernet.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8732381B2SAS expander for communication between drivers

Publication Date: 2014.05.20 HEWLETT PACKARD ENTERPRISE DEV LP

AI summary

A SAS expander that includes a virtual device manager and a communications manager. The virtual device manager is to generate a virtual device table comprising virtual device PHYs associated with virtual device drivers for host device drivers to allow communication between the host device drivers. The communications manager is to receive a request from a first host device driver of a first host to communicate with a second host device driver of a second host, and in response to receipt of the request, establish communication between the first host device driver and a virtual device PHY associated with a virtual device driver of the second host device driver.