A performance evaluation of high-availability webserver cluster system employing multiple front-ends for small and middle-sized web sites

초록

A lot of clustering technologies have been applied to websites on these days. Webserver cluster can be configured with either high performance hardware switch or LVS (Linux Virtual Server) software. High performance hardware switch has good performance but has disadvantages of expensive cost at construction of small and middle-sized websites. LVS, which is free of charge and has good performance, have commonly been used to construct Webserver cluster. LVS is hampered by a single front-end which can be a bottleneck with increased request, and a failed front-end can disable the cluster system. In this paper, we suggest a new architecture based on LVS with multiple front-ends which also acts as back-ends. This architecture removes a bottleneck, and is useful in configuring small and middle-sized web sites. A scheduling algorithm with considering servers' load is proposed to keep load even between servers. In this scheduling algorithm, when a server's load is not large enough, the server makes response to the client directly. Otherwise, the server redirect the request to a selected back-end with the lowest load. While the Webserver cluster with single front-end raises the throughput curvedly, the Webserver cluster with multiple frontends raises the throughput linearly.