Optimal Backup Policies for a Database System with Periodic Incremental Backup

This paper considers the following backup scheme for a database system: a database is updated at a nonhomogeneous Poisson process and an amount of updated files accumulates additively. To ensure the safety of data, full backup are performed at time NT=L or when the database fails, whichever occurs first, and between them, incremental backups are made at periodic times iT (i=1, 2, …, N-1) so as to make the backup efficiently. Using the theory of cumulative processes, the expected cost is obtained, and an optimal numbers N* of incremental backup which minimizes it given T or L are analytically discussed. Finally, it is shown as an example that optimal numbers are numerically computed.