In Mobile Distributed systems, we come across some issues like: mobility, low bandwidth of wireless channels and lack of stable storage on mobile nodes, disconnections, limited battery power and high failure rate of mobile nodes. Fault Tolerance Techniques enable systems to perform tasks in the presence of faults. The likelihood of faults grows as systems are becoming more complex and applications are requiring more resources, including execution speed, storage capacity and communication bandwidth. A checkpoint is a local state of a process saved on stable storage. In a distributed system, since the processes in the system do not share memory, a global state of the system is defined as a set of local states, one from each process. In case of a fault in distributed systems, checkpointing enables the execution of a program to be resumed from a previous consistent global state rather than resuming the execution from the beginning. In this way, the amount of useful processing lost because of the fault is significantly reduced. Checkpointing is an effective fault tolerant technique in distributed system as it avoids the domino effect and require minimum storage requirement. Most of the earlier coordinated checkpoint algorithms block their computation during checkpointing and forces minimum-process or non-blocking even though many of them may not be necessary or non-blocking minimum-process but takes useless checkpoints or reduced useless checkpoint but has higher synchronization message overhead or has high checkpoint request propagation time. In this paper, we present a survey of some checkpointing algorithms for distributed systems.
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