Testbed architecture

The Web cluster consists of a Web switch node, and up to seven Web servers. Each machine is a Dual PentiumIII-833Mhz PC with 512MB of memory. All nodes of the cluster use a 3Com 3C905C 100bTX network interface. They are all equipped with a Linux operating system (kernel release 2.4.18). Apache 2.0 is used as the Web server software. Dynamic pages are implemented by means of PHP scripts which stress various system components, such as the CPU or the disk. The clients and servers of the system are connected through a switched 100Mbps Ethernet. We used a modified version of the httperf tool [20] (version 0.8) as a benchmarking tool.