Web applications and dynamic reconfiguration in UNIX servers

In recent years, several large UNIX SMP Servers have added support for dynamic resource management through partitioning and dynamic resource reconfiguration. In this paper we study the ability of Dynamic Reconfiguration (DR) to accommodate fluctuating workloads and changes in operational priorities for a commercial web application. We use a WebSphere HTTP server, a WebSphere Application Server, and a DB2 Database for the application. This combination represents a popular platform for commercial computing deployments, and supports a number of common web-based application scenarios. In our study, we treat this application as a black box to provide a realistic measurement of the efficacy of the DR technology in UNIX Servers. We also use nonparametric estimation techniques to obtain an ab initio and unbiased study of the jitters in our experimental data. Our main conclusions are: (1) Resource allocations for the application (even for a complex and function-rich middleware system such as WebSphere) can be efficiently managed by DR, without the need for explicit accommodation of the DR features by the application, and (2) To obtain efficient resource utilization, the resource management system has to empirically monitor the throughput obtained from the application, rather than rely primarily on long time-scale estimations.