Vageesan, Gopinath (2005-12). On improving performance and conserving power in cluster-based web servers. Master's Thesis. Thesis uri icon


  • Efficiency and power conservation are critical issues in the design of cluster systems
    because these two parameters have direct implications on the user experience and the
    global need to conserve power. Widely adopted, distributor-based systems forward client
    requests to a balanced set of waiting servers in complete transparency to the clients. The
    policy employed in forwarding requests from the front-end distributor to the backend
    servers plays an important role in the overall system performance. Existing research
    separately addresses server performance and power conservation. The locality-aware
    request distribution (LARD) scheme improves the system response time by having the
    requests served by web servers which have the data in their cache. The power-aware
    request distribution aims at reducing the power consumption by turning the web servers
    OFF and ON according to the load.
    This research tries to achieve power conservation while preserving the performance of the
    system. First, we prove that using both power-aware and locality-aware request
    distribution together provides optimum power conservation, while still maintaining the
    required QoS of the system. We apply the usage of pinned memory in the backend servers to boost performance along with a request distributor design based on power and locality
    considerations. Secondly, we employ an intelligent-proactive-distribution policy at the
    front-end to improve the distribution scheme and complementary pre-fetching at the backend
    server nodes. The proactive distribution depends on both online and offline analysis of
    the website log files, which capture user navigation patterns on the website. The prefetching
    scheme pre-fetches the web pages into the memory based on a confidence value of
    the web page predicted by backend using the log file analysis. Designed to work with the
    prevailing web technologies, such as HTTP 1.1, our scheme provides reduced response
    time to the clients and improved power conservation at the backend server cluster.
    Simulations carried out with traces derived from the log files of real web servers witness
    performance boost of 15-45% and 10-40% power conservation in comparison to the
    existing distribution policies.

ETD Chair

  • Kim, Eun  Associate Professor - Term Appoint

publication date

  • December 2005