| IP Storage Area Network (IP-SAN) technology is very important in the area of storage. It not only has the advantages of simple configuration and management, but also provides high capability and expansibility, which are the features of SAN. iSCSI is an critical protocol in the realization of accessing storage devices. Remote boot technology based on iSCSI protocal can boot from IP-SAN with the help of PCI ROM (such as NIC), it simplifies the infrastructure, and centralizes the the tasks of management. IP-SAN rebmote boot technology gives clients the ability to boot from mapping disks, which seems like every client has a local SCSI device, but how to allocate a mapping storage volume to a client, and how can they lauch the operating system on the mapping disk?In order to solve these problems, a block-based, reliable iSCSI/TCP protocol stack model is designed and implemented in this paper. A new remote boot technology based on IP storage area network was designed, the core technology of it is the firmware protocol stacks running under bare machine platform. The details are as follows:(1) A non-routing TCP protocol prototype was proposed and implemented based on firmware. The TCP protocol state machine is redesigned to make it simple. At the same time, several optimization algorithms were introduced to enhance the performance and reliability of remote boot, including optimistic forecast, fixed avoiding retransmit algorithm and output request suspend strategy that solved the problem of reentry.(2) After carefully analysed the iSCSI initiator architecture, we designed a firmware iSCSI initiator Finite State Machine model which can be easily taken over by kernel mode initiator. On top of this, we designed and implemented a simplified iSCSI initator, which is efficient, stable and does not require many resources; finally we designed the service of Disk Access Redirection and Boot Connection Vector, shows the details of how to boot from IP-SAN.(3) We fully tested the function, performance and reliability of the iSCSI/TCP protocol stack; then compared the IP-SAN remote boot system based on iSCSI/TCP firmware protocol stack with other relevant systems; After that, we suggested some further optimization and improvement options. The firmware protocol stack was integrated into IP-SAN extension BIOS, and applied to client hosts with no local storage devices, achieves network boot based on IP-SAN. Test results show it has a very good performance. Deployment, movement and re-distribution of relations between hosts and storages becomes more easily. Truely realized network boot and storage. |
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