Studies On Storage Virtualization Technologies For Heterogeneous Storage Area Networks

Virtualization is an essential technology to improve the manageability of SAN system. In this paper the design and implementation of an out-of-band storage virtualization system under heterogeneous SAN environment, the THVSS, is presented. THVSS adopts an out-of-band architecture where the data flow and control flow is separated and therefore has the flexible manageability and the high performance. Further, there is a specialized metadata server in the THVSS which is responsible to manage, configure and deploy storage resources; and the client software running at application servers performs the address mapping from virtual addresses to physical addresses. It makes THVSS advantaged to support heterogeneous platforms for application servers. Moreover, THVSS can distributes the storage resource among application servers according to the delay, bandwidth, reliability and other performance targets and satisfy user's requirement in a multi-dimension space.Particularly, the design and implementation of the client software under Windows NT and Solaris 10 is emphatically discussed in this paper. Under those two platforms the client software consists of the kernel module and communication module. The former performs virtualization functions, including the creating of virtual volumes, the mapping of read and write from virtual devices to physical devices, etc. The latter communicates with the metadata server and assists kernel module to manage virtual devices. In THVSS, client software along with the metadata server provides application servers with virtual storage devices whose volume is not limited by the volume of a certain physical device and having a high bandwidth, they also achieve a central management mechanism of the storage resource in SAN which can significantly reduce works required for a system administrator.The testing result revealed that our virtualization approach could make use of the storage resources in SAN more effectively and the overhead induced by our approach is much low. The comparison with a plain SAN under FAT32 and NTFS, using...