The rapid growth of eCommerce increasingly means busi- ness revenues depend on providing good quality of service (QoS) for web site interactions. Traditionally, system administrators have been respon- sible for optimizing tuning parameters, a process that is time-consuming and skills-intensive, and therefore high cost. This paper describes an ap- proach to automating parameter tuning using a fuzzy controller that employs rules incorporating qualitative knowledge of the effect of tuning parameters. An example of such qualitative knowledge in the Apache web server is “MaxClients has a concave upward effect on response times.” Our studies using a real Apache web server suggest that such a scheme can improve performance without human intervention. Further, we show that the controller can automatically adapt to changes in workloads.