On the Optimum Checkpoint Interval

One of the basic problems related to the efficient and secure operation of a transaction oriented file or database system is the choice of the checkpoint interval In this paper we show that the optimum checkpoint interval (i e the time interval between successive checkpoints which maximizes system avadabihty) is a function of the load of the system We also prove that the total operating time of the system (and not the total real time) between successive checkpoints should be a deterministic quantity in order to maximize the availability An explicit expression for this time interval Is obtained These results are a significant departure from previous work where load independent results have been obtained We also present a rigorous analysis of the queuelng process related to the requests for transaction processing arriving at the system, and prove the ergodiclty conditions for the system