High Availability Transactions

This thesis presents a framework of a passively replicated transaction manager. By integrating transactions and replication, two well known fault tolerance techniques, the framework provides high availability for transactional systems and better support for non-deterministic execution for replicated systems. A prototype Java implementation of the framework, based on Jgroup/ARM and Jini, has been developed and performance tests have been executed. The results indicate that the response time for a simple credit-debit transaction heavily depends on the degree of replication for both servers and the transaction manager. E.g. a system with two replicas of the transaction manager and the servers quadruples the response time compared to the nonreplicated case. Thus, the performance penalty of replication should be weighed against the increased availability on a per application basis