Design and Implementation of a SAN Agent for Windows NT Architecture

In an out-of-band SAN virtualization system, the virtualization appliance maintains metadata, and the agents inside the kernel of servers use that data to supply virtual storage devices and to perform the mapping of I/O address. A design of an out-of-band SAN virtualization system based on Windows NT volume manager driver, and its underlining technologies were presented in this paper. It shows that, in general our system is able to supply large volume and high bandwidth virtual storage devices for applications, and it can be used as a basic environment to manage the SAN centrally. The system performance was investigated in comparison with a plain SAN under FAT32 and NTFS, using different data block sizes and access patterns. The results reveal that the overhead induced by our approach is much low. Under FAT32, the performance characteristics of the 3-striped virtual volume follow a typical strip distribution strategy and the bandwidth is 1.20 3.71 times greater than general volume. Furthermore, under NTFS, the bandwidth of the 3-striped virtual volume is an average of 4.10 (max 4.82) times greater than general volume with the random read access test. Hence it can be concluded that our virtualization approach could make use of the storage resources in SAN more effectively.