V: Drive - Costs and Benefits of an Out-of-Band Storage Virtualization System

The advances in network technology and the growth of the Internet together with upcoming new applications like peer-to-peer (P2P) networks have led to an exponential growth of the stored data volume. The key to manage this data explosion seems to be the consolidation of storage systems inside storage area networks (SANs) and the use of a storage virtualization solution that is able to abstract from the underlying physical storage system. In this paper we present the first measurements on an out-of-band storage virtualization system and investigate its performance and scalability compared to a plain SAN. We show in general that a carefully designed out-of-band solution has only a very minor impact on the CPU usage in the connected servers and that the metadata management can be efficiently handled. Furthermore we show that the use of an adaptive data placement scheme in our virtualization solution V:Drive can significantly enhance the throughput of the storage systems, especially in environments with random access schemes.