USENIX Technical Program - Abstract - Windows NT Symposium 99
HACC: An Architecture for Cluster-Based Web Servers
Xiaolan Zhang, Michael Barrientos, J. Bradley Chen, and Margo Seltzer, Division of Engineering and Applied Sciences, Harvard University
This paper presents the design, implementation, and performance of the
Array of Clustered Computers (HACC), a cluster-based design for
scalable, cost-effective web servers. HACC is designed for locality
enhancement. Requests that arrive at the cluster are distributed
among the nodes so as to enhance the locality of reference that occurs
on individual nodes in the cluster. By improving locality on
individual cluster nodes, we can reduce their working set sizes and
achieve superior performance for less cost than conventional
approaches. We implemented HACC on Windows NT 4.0 and evaluated its
performance for both static documents and workloads of dynamically
generated documents adapted from logs of commercial web servers. Our
performance results show that HACC's locality enhancement can improve
performance by up to 121% for our stochastically generated static file
case, by up to 40% for our trace-based static file case, and by up to
52% for our trace-based dynamic document case, compared to an IP-
Sprayer approach to building cluster-based web servers.
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