Rejuvenation is a technique expected to mitigate failures in HPC systems by replacing, repairing, or resetting system components. Because of the small overhead required by software rejuvenation, we primarily focus on OS/kernel rejuvenation. In this paper, we propose three rejuvenation scheduling techniques. Moreover, we investigate the claim that software rejuvenation prolongs failure times in HPC systems. Also, we compare the lost computing times of the checkpoint/restart mechanism with and without rejuvenation after each checkpoint.