Cost-Effective Remote Mirroring Using the iSCSI Protocol

This paper presents a performance study of the iSCSI protocol in the context of remote mirroring. We first integrate our caching technology called DCD (disk caching disk) into a standard iSCSI target device to form a high performance storage system for mirroring purpose. Performance measurements are then carried out using this storage system as well as standard iSCSI targets as mirroring devices. We consider remote mirroring on a LAN (local area network) and on a commercial WAN (wide area network). The workloads used in our measurements include popular benchmarks such as PostMark and IoMeter, and real-world I/O traces. Our measurement results show that iSCSI is a viable approach to cost-effective remote mirroring for organizations that have moderate amount of data changes. In particular, our DCDenhanced iSCSI target can greatly improve performance of remote mirroring.