SCSI子系统中间层多启动互连多路径I/O的存储方式的研究

面对当前应用对现代存储的高性能以及可用性、可靠性的新的要求，在Multi—Initiator—Uni—Port的基础之上提出了SCSI中间层多启动互连多路径I／O的存储方式．它能够在Multi—Initiator—Uni—Port的连接中对同一个Target端口采用不同的I／O路径进行存储，减少了由于单路径I／O传输错误导致系统单点失效的可能性，增强了存储系统的可用性和可靠性；同时，这种存储方式还能够很好地平衡系统的I／O负载，提高系统的吞吐率，提供比传统单路径更好的传输性能．在Linux2．4内核中的SCSI子系统的基础之上实现了这种存储方式，向系统屏蔽了SCSI子系统中的设备具体细节，并且不依赖于SCSI上层的实现，减少了对系统内核的资源占有率，提高了SCSI底层的执行效率．分析了SCSI中间层多启动互连多路径I／O的存储方式的原理，并且将iSCSI的体系结构应用到它的模拟测试中，得到了R—R路径选择分配策略的性能临界点，取得了令人满意的结果．

Research of the Storage Mode of SCSI Subsystem Mid-Level Multi-Initiated Interconnect Multi-Path I/O

In the face of the current application's new requirement to the availability and reliability of modern storage, this paper puts forward a new storage mode named the SCSI Mid-level Multi-Initiated Interconnect Multi-Path I/O mode, which can carry out I/O to the same Target Port among multi-Initiator-Uni-Port connection, This storage mode reduces the possibility of system's single-point invalidation, and improves the system's availability and reliability as well; and at the same time, this storage mode can balance the system's workload, improve the system's throughput, and provide better transmission performance than conventional single I/O path. This paper implements this storage mode in the SCSI subsystem under Linux 2.4 kernel. It hides the device's details of the SCSI subsystem, meanwhile, the implementation does not depend on the implementation of SCSI Upper-level, reduces the usage of the kernel resource and improves the efficiency of the SCSI Low-level as well. This paper analyzes the principle of the SCSI Mid-level Multi-Initiated Interconnect Multi-Path I/O mode, and utilizes the iSCSI architecture into the simulation test, meanwhile, this paper acquires the critical point of the R-R path selection-assignment strategy. The result is satisfactory.