Optimal checking time of backup operation for a database system

When a failure occurs in the process of a database system, we execute the rollback operation until the latest checking time and make the recovery of database of files. This paper proposes the modified inspection model where the backup is carried out until the latest checking time when some failure was detected. The expected cost until the backup operation is made to the latest checking time is derived, and optimal inspection policies, which minimize it for two cases of periodic and sequential checking times, are analytically discussed. Some further modified models where the operating time is finite and a fault remains hidden are proposed.