Service Policies for a Storage Services Dispatcher in a Distributed Fault-Tolerant Storage Network and their Performance Evaluation

摘要

In this paper we consider an experimental low-cost fault-tolerant storage network. One station of the system is in charge of receiving service requests coming from the users (i.e., file storage or retrieval). We call this station a storage services dispatcher. We propose and evaluate two different service policies to be implemented at the dispatcher. In the first one the dispatcher processes each file to be stored and retrieved. In the second service policy the dispatcher assigns some of these tasks to the computers of the storage network. We detail the protocols that implement both service policies and evaluate their performance through discrete-event simulations. From the obtained results we concluded that even though the second service policy leads to higher link congestion in the storage network, overall it turns out to be more appropriate in order to diminish performance degradation resulting from overload at the dispatcher.