ANALYSIS OF RECOVERY PROTOCOLS IN DISTRIBUTED ON-LINE TRANSACTION PROCESSING SYSTEMS.

To meet the growing demand for online transaction processing, several DB (database management) and DC (data communication management) subsystems can be coupled together to form a distributed DB/DC system. A recovery protocol is needed not only to provide for the recovery of transactions affected by the failure, but also to localize recovery operations. Two such protocols based on a progressive approach, namely, a synchronous progressive and an asynchronous progressive protocol, along with a pessimistic protocol, are analyzed. Their performance during normal transaction processing is contrasted with that of a transaction processing system without any recovery protocol. A queuing model is developed and simulated to predict the transaction response time. The progressive recovery approach is found to reduce normal processing overhead and lead to performance improvement over the pessimistic approach.