Abstract
In large-scale grids, the replication of files to different sites and the appropriate scheduling of jobs are both important mechanisms which can reduce access latencies and give improved usage of resources such as network bandwidth, storage and computing power. In the search for an optimal scheduling and replication strategy, the grid simulator OptorSim was developed as part of the European DataGrid project. Simulations of various high energy physics (HEP) grid scenarios have been undertaken using different job scheduling and file replication algorithms, with the emphasis being on physics analysis use-cases. An economy-based strategy has been investigated as well as more traditional methods, with the economic models showing advantages for heavily loaded grids.