TH-VSS: An asymmetric storage virtualization system for the SAN environment

Abstract

Storage virtualization is a key technique to exploit the potential of SANs. This paper describes the design and implementation of a storage virtualization system for the SAN environment. This system has asymmetric architecture, and virtualization operations are done by a metadata server allowing management to be accomplished at a single point. The system has better scalability compared to symmetric systems and can support heterogeneous platforms of hosts. Agent software was implemented in the volume management layer of hosts so that any standard HBA card can be used. The metadata server manages storage resources automatically and configuration of storage pools can be changed dynamically. The metadata server is also used for system monitoring, which is the basis of dynamic storage resource management and automatic failure recovery. Test results showed that the overhead introduced by our virtualization layer is negligible, and the performance of storage system was enhanced effectively by the striping strategy in organizing storage pools. The number of seeks per second to a logical volume allocated from a pool of four disks was increased by 55.2% compared to a plain FC disk. © Springer-Verlag Berlin Heidelberg 2005.