Studies on Stochastic model of Server Systems with Replication

近年来，复制被广泛应用于企业数据库的保护。当主站点因飓风、地震等原因出现故障时，备份站点会等待警报。服务器通过网络将数据库内容从主站点传输到备份站点。这称为复制。本研究使用数据库文件和日志文件相结合的备份方法，建立了具有复制的服务器系统的随机模型。另一方面，为了缩短响应时间和平滑通信负载，采用复制缓冲中继法建立了服务器系统的随机模型。此外，我们还解析地推导了复制和故障恢复的预期成本。此外，我们还讨论了数据库备份方法的优化策略。研究成果已在多个国际会议和国际期刊上发表。

Recently, the replication has been widely used to protect enterprise database. The backup site stands by the alert when a main site has broken down due to hurricanes, earthquakes, and so on. The server transmits the database content from the main site to the backup site through networks. This is called replication. This research has formulated stochastic models of a server system with replication using a backup method combined database files with journaling files. The other hand, we have formulated stochastic models of a server system with the replication buffering relay method for shortening response time and smooth communication load. Moreover, we have derived the expected costs of the replication and failure recovery analytically. Further, we have discussed optimal policies about database backup method. Research results have been published many international conferences and international journals.