Web proxy analysis in distributed iSCSI RAIDs

With the popularity of Web services and e-commerce, we have a high demand on data storage. Because of the development of the Internet infrastructure and the low cost of deployment, implementing storage over IP has become a trend. While networked storage brings economy, it also raises performance concern. In a typical distributed Web system, I/O requests from clients users may be satisfied by many different parties along the I/O path from front-end clients to back-end storage systems via proxy and Web servers. To improve the performance, we need to identify the I/O distribution pattern along the path. This paper analyzes the I/O distribution along the I/O path of a distributed iSCSI RAID system by using kernel counters and profiles how the I/O requests are satisfied at different levels of the proxy server and storage system, which is useful to identify the performance bottleneck.