Modeling And Evaluation Of The Virtual Storage System Based On ISCSI

With the rapid development of digital information technology and computer networks,many enterprises treated data storage as an important project to manage in the face of the explosive growth of data size.However,the management of these devices tents to be very difficult.In this background,storage virtualiztion technology was applied to solve the differences between the storage devices,the integration of different storage resources and the efficient management of different storage devices.The Storage Area Network(SAN)can connect the servers and storage facilities to become an independent network with high performance.Therefor,it was widely adopted as a kind of effective storage implementation resolution.The IP-SAN system based on iSCSI(Internet Small Computer System Interface)witch uses mature TCP/IP network architecture has the advantages such as simple management,low cost,strong expansibility and so on.The iSCSI protocol between the proposed more than ten years,got rapid development and it was currently a major trend in strorage field.On current iSCSI technology research,they most focus on iSCSI system implementation and system performance improvement.But there is little research for iSCSI system of formal work.Colored Petri Net as a good formal modeling language,has a strict mathematical definition,in computer network performance evaluation,the analysis and design of the distributed system,validation of network protocol,and many other fields has a wealth of application experience.Its powerful ability of simulation analysis and state space analysis technology can help us to verify this system internal logic correctness.This paper gives a detailed analysis of the connection and session management in iSCSI system.Then,based on the jobs above,we using CPN as modeling language and modeling method based on state,give a formal description of the connection and session management in iSCSI system.Finally we get a multi-level CPN model.The model not only has the basic function of iSCSI connection and session management module,but also strictly follows RFC3720(iSCSI protocol standard)description.According to this model,we using CPN Tools,make simulation execution and state space analysis under the condition of a variety of state.We test whether the connection and session management process logic in iSCSI system is correct.We found some logical problems under some simulated conditions,and analyzed the reasons of the logical mistakes.Finally,we give some suggestion that we shoule pay attention to in the process of iSCSI system implementation.