Abstract
Nowadays, Data Grids are can be seen as a frameworks responding to the needs large scale applications by affording varied geographically distributed resources set. The main aim here is to ensure a robust and efficient access and quality data, to improve the availability, we must improve application costs and to tolerate the faults. In such systems, these advantages are not yielded by means others than replication mechanisms. The effective use the replication technique involves several problems, in relation with the problem of the coherence maintenance of replicas. Our contribution consists new approach for the consistency management in the data grid. The proposed approach combines between pessimistic and optimistic approaches, taking into account benefits of both approaches, to find a compromise between performance and quality. In addition, our approach has been extended by c mechanism placement of replicas based on models of market economies.