Open Access

Nizar Msadek, Theo Ungerer

• Replication typically occurs in a wide range of open distributed systems, especially in self-healing systems (i.e., mainly for fault-tolerance purposes) and in high-performance computing (i.e., mainly for fast response times). All these systems face a common issue: how can replicas automatically and efficiently be managed in a system despite changing requirements of their environment? One way to overcome this issue is trust. The contribution of this paper is a novel approach based on trust that provides a good management of replicas --- especially for those of important services --- despite uncertainties in the behavior of nodes. Depending on the importance level of a service possessing the replicas and the assessment of the trustworthiness of a node, we can optimize the trust distribution of replicas at runtime. For evaluation purposes we applied our approach to an evaluator based on the TEM middleware. In this testbed, the usage of trust reduced the replication overhead by about 1 4%Replication typically occurs in a wide range of open distributed systems, especially in self-healing systems (i.e., mainly for fault-tolerance purposes) and in high-performance computing (i.e., mainly for fast response times). All these systems face a common issue: how can replicas automatically and efficiently be managed in a system despite changing requirements of their environment? One way to overcome this issue is trust. The contribution of this paper is a novel approach based on trust that provides a good management of replicas --- especially for those of important services --- despite uncertainties in the behavior of nodes. Depending on the importance level of a service possessing the replicas and the assessment of the trustworthiness of a node, we can optimize the trust distribution of replicas at runtime. For evaluation purposes we applied our approach to an evaluator based on the TEM middleware. In this testbed, the usage of trust reduced the replication overhead by about 1 4% while providing a much better placement of important replicas than without trust.…