Preventing useless checkpoints in MANETs

A global checkpoint of a distributed computation is formed by a set of local checkpoints, one from each process in the system. However, a local checkpoint taken by a process may be useless if it cannot be part of any consistent global checkpoint. Since checkpointing is expensive in MANETs due to the limitation of available resources, such useless checkpoints need to be prevented for an efficient checkpointing procedure. This paper presents an independent checkpointing protocol for MANETs which prevents useless checkpoints and thus, avoids domino effect during rollback recovery. The proposed protocol is based on the results of zigzag paths and zigzag cycles by Netzer-Xu [3]. A checkpoint is useless if it is involved in a z-cycle which happens when there is a dependency from the checkpoint to itself. The protocol uses the popular graph theoretic construct called Connected Dominating Set (CDS) to track dependencies between checkpoints in order to eliminate z-cycles.