Research On Asymmetric ISCSI Protocol Based On Ethernet

With the information age, mass data storaged and processed is the key issue, thecenter of computer system will be gradually transferred to the storage system.Therefore, the development of network storage, especially the emergence of storagesystems based on Ethernet, it is possible that the network storage systems becomepopular. Currently，Ethernet storage system is mainly based on iSCSI of TCP protocol,implementation of TCP protocol is a little more conservative，using low bandwidth,taking up more CPU resources.As a result, overhead of iSCSI protocol is too highcausing the system performance decreased, improving transport protocol performancecan change iSCSI storage systems performance.For these reasons, this paper presents the research of asymmetric iSCSI protocolbased on Ethernet, which uses UDP and TCP at the transport layer, TCP is mainlyused for dynamic rate control and retransmission handling, and make them as aparallel transport layer of iSCSI protocol stack.Major research work completed of this paper as follows:(1) High-speed reliable UDP protocols: Reliable UDP at the application layer,application layer and kernel layer are both designed UDP buffers, and gives acomputable model to optimize the feature parameters (buffer size, transmission rate,etc.). The data flow and structure of the sender and receiver as well as dynamic ratecontrol algorithm are detail descripted. Simultaneously, a data sorted algorithm ofbuffer and a optimizing memory management algorithm are designed.Finally,high-speed reliable UDP protocols and other UDP-based protocol are comparativelyanalyzed.(2) Improvements of iSCSI based on high-speed reliable UDP protocol: TheiSCSI PDU is extended to support UDP data transfer, and adding supplements ofcommand connection allegiance, then using the Finite State Machine model andColored Petri Nets to symplify the states of the iSCSI connection.(3) Design and experimental analysis of iSCSI based on high-speed reliable UDPdata transfer:Proposing asymmetry iSCSI model based on the UDP protocol for datatransmission，the data number and errors recovery mechanism of iSCSI are used forguaranteeing the data reliable,read and write processing of the new iSCSI aredescribed and compared by experiments to test the performance of asymmetric iSCSI with standard iSCSI.Experimental results show that the asymmetric iSCSI can improve about20%to30%of the read throughput,20%to25%of the write throughput,and reduce by10%to15%CPU utilization. It fully shows that advantages of high-speed reliableUDP-based data transfer asymmetric iSCSI protocol.