In real-time database systems, data is replicated to enhance the response time in processing transactions. When the data is replicated, the one-copy serializability must be maintained. In maintaining serializability, blocking delay of transactions has a major effect on the response time of transactions. In this thesis, a method using distinct copies is proposed for enhancing the response time of transactions, and the performance of the proposed method is analyzed. The proposed method eliminates read-write conflicts by sacrifying complete serializability. Based on the simulation results, the average response times of the proposed method was smaller than those of the read-one/write-all method, which is a wellknown concurrency control method in replicated database systems. In addition, the consuming time for site recovery is mostly eliminated by treating the recovered site as a writable site.
