Reliability Characteristics of a Server System with Asynchronous and Synchronous Replications

Abstract

Recently, replication mechanisms for a disaster recovery have been widely used for the server system. This paper considers the reliability in server systems with synchronous and asynchronous replications for the disaster recovery. We formulate two stochastic models of server systems with synchronous and with asynchronous replications: In synchronous replication, the server transmits the database content to a backup site as soon as a main site updates the storage database. In asynchronous replication, the server transmits the database content to a backup site after a constant time. We derive the expected number of the replication and the probability of migrating routine work to the backup site and the probability of the system down. Further, in asynchronous model, we calculate the cost effectiveness and discuss an optimal policy to minimize it. Finally, in asynchronous and in synchronous models, numerical examples are given to compare the performance of them.

Key Words:

• Asynchronous
• cost effectiveness
• disaster recovery
• replication
• synchronous

Additional information

Notes on contributors

Kimura Mitsutaka

Mitsutaka Kimura is an Associate Professor at the Department of International Culture Studies, Gifu City Women’s College. He received his Ph.D. in Engineering from Nagoya Institute of Technology. His research interests include reliability of network systems.

Imaizumi Mitsuhiro

Mitsuhiro Imaizumi is an Associate Professor at the College of Business Administration, Aichi Gakusen University. He received his Ph.D. in Engineering from Aichi Institute of Technology. His research interests include reliability of computer systems.

Nakagawa Toshio

Toshio Nakagawa is a Professor at the Department of Business Administration, Aichi Institute of Technology. He received his Ph.D. in Engineering from Kyoto University. His research interests include reliability theory and reliability of computer systems.