PCIe Tunneling Through SAS Expanders
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Solution Overview
Problem
The integration of PCIe-based storage devices with traditional SAS domains is challenging due to the packet-based, connectionless nature of PCIe protocols and the end-to-end, connection-based nature of SAS protocols, which hinders effective data transfer and interworking.
Innovation Solution
The implementation of a system that tunnels PCIe traffic through a SAS domain using PCIe capable SAS expanders, traditional SAS expanders, and PCIe capable SAS controllers, allowing PCIe target devices to connect to a PCIe-based host system via a SAS domain by establishing SAS connections and buffering data packets for transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PCIe-based storage devices are integrated with traditional SAS domains, then storage system versatility is improved, but protocol compatibility issues arise due to PCIe being packet-based and connectionless while SAS is connection-based
Solution Approach 1:
The patent introduces SAS expanders with PCIe tunneling capability as intermediary devices that bridge the PCIe and SAS domains. These expanders act as protocol translators, converting PCIe packet-based traffic into SAS connection-based traffic for transit through the SAS domain, while maintaining native PCIe interfaces for host and storage devices. This mediator approach resolves the protocol compatibility issue without requiring direct PCIe-to-SAS protocol conversion at the host level.
Solution Approach 2:
The system segments the storage architecture into distinct domains (PCIe domain for host and direct-attached storage, SAS domain for shared storage) connected through intermediary expanders. This segmentation allows each domain to operate with its native protocol (PCIe for connectionless access, SAS for connection-based shared access) while the expanders handle protocol translation at the boundaries, reducing overall system complexity.
2Adaptability or versatility
If PCIe traffic is tunneled through SAS connections, then connection between PCIe target devices and host system is enabled, but data transfer efficiency may be reduced due to protocol translation overhead
Solution Approach 1:
The SAS expander with PCIe tunneling capability serves as an efficient intermediary that minimizes protocol translation overhead by performing conversions at the hardware level rather than software level. The expander maintains direct hardware pathways for data translation between PCIe and SAS protocols, reducing processing latency while enabling connectivity between PCIe target devices and the host system through the SAS domain.
Data Source
AI summary
Systems and methods presented herein provide for tunneling PCIe data through a SAS domain. a data system includes a SAS expander, a PCIe target device coupled to the expander, and a SAS controller communicatively coupled to a host system and the expander. The controller is operable to open a connection with the expander via the SAS protocol, and to transport packet data between the target device and the host system through the connection via the PCIe protocol. For example, the controller and the expander may be operable to buffer packets of data in the connection. The controller may issue a number of the data packets to be transferred in the connection. Then, the issued number of data packets are transported between the target device and the host system through the connection via the PCIe protocol.