Conventional distributed and domino effect-free failure recovery techniques are inappropriate for mobile computing systems because each mobile host is forced to take a new checkpoint (based on coordinated checkpointing). Otherwise, multiple local checkpoints may need to be stored in stable storage (based on communication-induced checkpointing). Hence, this investigation presents a novel domino effect-free failure recovery technique that combines the merits of the above two checkpointing technologies for mobile computing systems. The algorithm is a three-phase protocol that ensures a consistent checkpoint. The first phase uses a coordinated checkpointing protocol among mobile support stations. In the second phase, a communication-induced checkpointing protocol is used between each mobile support station and its mobile hosts. In the last phase, each mobile support station sends a checkpoint request to its mobile host which hasn¡¦t received any message from the mobile support station during the second phase. Numerical results are provided which compare the proposed algorithm with both a quasi-synchronous failure recovery algorithm and a hybrid checkpoint recovery algorithm for mobile computing systems. According to the comparison, our scheme outperforms other schemes in terms of checkpoint overhead. Moreover, the proposed algorithm has several merits: domino effect-free, nonblocking, twice the checkpoint size, and scalability.

Keywords: mobile computing systems, checkpointing, failure recovery, domino effect, consistent global checkpoints

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Received May 3, 1999; revised December 17, 1999 & March 20, 2000; accepted June 12, 2000.
Communicated by Yi-Bing Lin.
^* This work is partially supported by National Science Council of the Republic of China under contract NSC-88-2213-E035-039.