Impact of QoS on Replica Placement in Tree Networks

Abstract

Abstract. This paper discusses and compares several policies to place replicas in tree networks, subject to server capacity and QoS constraints. The client requests are known beforehand, while the number and location of the servers are to be determined. We study three strategies. The first two strategies assign each client to a unique server while the third allows requests of a client to be processed by multiple servers. The main contribution of this paper is to assess the impact of QoS constraints on the total replication cost. In this paper, we establish the NP-completeness of the problem on homogeneous networks when the requests of a given client can be processed by multiple servers. We provide several efficient polynomial heuristic algorithms for NP-complete instances of the problem.

Modeling the Web as a Forest of Trees

“…Each server s knows the preference path from itself to any client c . This information can be extracted and periodically refreshed from the routing database kept by the routers (Anne Benoit et al, 2006). The routing information allows the comparison of network distances (e.g.…”

“…Replication is a technique of storing copies of shared objects on servers where they are frequently accessed. It is used to address the scalability problem of popular sites (Anne Benoit et al, 2006). Replication improves efficiency by allowing operations to use local replicas instead of remote ones (Anne Benoit et al, 2006, F. Tenzakhti et al, 2003.…”