Dynamic reliability as an alternative to overall data base restoration

A model and mechanism for the dynamic reliability and recovery of data base search failures is described. This is an alternative to a complete data base restoration needed in most cases of hardware or software conditions that cause failures of search processes. The model, based on Petri Nets and Statecharts, facilitates the description of search processes and failure conditions and is applicable to hierarchical and network data bases. It is the basis of a recovery mechanism which bypasses the faulted area and routes the search to its destination in an alternate way. Implementation considerations are discussed. A comparison of the model against recovery features of a commercial DBMS package suggests a significant improvement in system reliability.