PCIe Switch Logical Device Consolidation
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Solution Overview
Problem
Current PCIe switch technologies lack the ability to effectively consolidate the functionality of multiple devices, leading to inefficiencies in resource sharing and management, particularly in scenarios involving SSD drives and other storage devices, where sharing resources among connected hosts is not natively supported.
Innovation Solution
The implementation of a synthetic or logical device within a PCIe switch, enabled by software in the management system, which creates shadow copies of local host component queues and utilizes DMA engines for automatic triggering, address mapping, and memory space redirection to consolidate physical devices into a logical endpoint, allowing for enhanced resource sharing and management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a standard PCIe switch is used without synthetic device capability, then the switch maintains simple architecture and operation, but it cannot consolidate functionality of multiple physical devices or enable resource sharing among multiple hosts
Solution Approach 1:
The patent introduces a synthetic device as an intermediary layer between physical devices and host systems. This synthetic device acts as a virtualization layer that consolidates multiple physical devices (such as SSDs) into a single logical endpoint, enabling resource sharing among multiple hosts without requiring complex modifications to the underlying physical device architecture or host interface logic
Solution Approach 2:
The patent creates shadow copies of command queues and data structures in the management system that mirror the local host's queue structures. These shadow queues enable the management system to track and manage device operations without requiring the local host to directly manage multiple physical devices, effectively copying the essential control structures to enable virtualization functionality
2Productivity
If physical devices are shared directly among multiple hosts without consolidation, then each host can access devices independently, but resource sharing efficiency is poor and management overhead is high
Solution Approach 1:
The patent merges multiple physical devices into a single synthetic device endpoint that presents a unified interface to host systems. By combining multiple SSDs or storage devices into one logical device, the system improves resource sharing efficiency while simplifying management, as hosts interact with a single consolidated endpoint rather than managing multiple individual devices
Solution Approach 2:
The synthetic device provides universal access to multiple physical devices through a single interface, enabling multiple hosts to share resources efficiently. The device can function as different types of endpoints (NVMe, SATA, SAS) depending on configuration, providing multi-functionality that enhances resource utilization across diverse host requirements
3Extent of automation
If shadow queues are created in the management system to reflect local host queues, then DMA engines can be automatically triggered and resource sharing is enabled, but memory usage and system overhead increase
Solution Approach 1:
The patent creates shadow copies of command queues in the management system's memory that mirror the local host's queue structures. These shadow queues contain essential command information needed to trigger DMA operations, providing an automated control mechanism while using minimal memory resources compared to full duplication of device state
Data Source
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AI summary
A PCIe switch implements a logical device for use by connected host systems. The logical device is created by logical device enabling software running on a host management system. The logical device is able to consolidate one or more physical devices or may be entirely software-based. Commands from the connected host are processed in the command and response queues in the host and are also reflected in shadow queues stored in the management system. A DMA engine associated with the connected host is set up to automatically trigger on queues in the connected (local) host. Commands are sent to the physical devices to complete the work and a completion signal is sent to the management software and a response to the work is sent directly to the connected host, which is not aware that the logical device is non-existent and is implemented by software in the management system.