In the paper, based on the job characteristics and resources availability, an optimistic checkpoint mechanism for dynamic grids（OCM4G） is proposed. It can determine whether to checkpoint a given job running on a given resource node and establish optimal aperiodic checkpoint intervals by applying the knowledge of job characteristics and resource availability. We evaluate OCM4G over a real grid environment （ChitlaGrid） and the results show that OCM4G achieves better performance than the periodic checkpoint and the analytical method of calculating aperiodic checkpoint intervals.
