Abstract
OptorSim is a Data Grid simulator, written in Java, which was initially developed by Work Package 2 of the European DataGrid project. The goal of OptorSim is to allow experimentation with and evaluation of various replica optimisation strategies. Using a Grid configuration and a replica optimisation algorithm as input, OptorSim runs a number of grid jobs on the simulated Grid. It also allow a user to visualise the performance of the algorithm. This document describes the installation and use of OptorSim.