Optimal checkpointing interval for two-level recovery schemes

It is important to design computer systems to tolerate some failures. This paper proposes two-level recovery schemes, soft checkpoint (SC) and hard checkpoint (HC), which are useful to recover from failures. Soft checkpoint is less reliable and less overhead than those of HC, and is set up between HCs to reduce the overhead of the process. The total expected overhead of one cycle from HC to HC is obtained, using Markov renewal processes, and an optimal interval which minimizes it is computed. It is shown in a numerical example that a two-level recovery scheme can achieve a good performance.