Abstract: Upon a receipt of an advance notice, an active system computer on which asynchronous replication is performed with a standby system computer stops a business application and transmits to the standby system computer transmission start information indicating start of data synchronization, data accumulated in a transmission queue 118, and transmission completion information indicating completion of the data synchronization in this order. The standby system computer generates and holds first reliability guarantee information indicating that the data received before the transmission start information upon a receipt of the transmission start information, and generates and holds second reliability guarantee information indicating that the data received before the transmission completion information is reliable data upon a receipt of the transmission completion information.

Abstract: A computer node connected with an upstream computer node and a downstream computer node so as to be capable of communicating therewith has a replication file system of a master file system, a storing unit, and a controlling unit. The controlling unit receives incremental data showing a changed part of the master file system from the upstream computer node, stores the incremental data into the storing unit, reflects the incremental data on the file system, and transfers the incremental data to the downstream computer node. Moreover, in a case that incremental data for plural times having received from the upstream computer node and having not transferred to the downstream computer node yet are accumulated in the storing unit, the controlling unit merges, with last received incremental data among the incremental data for plural times, the rest of the incremental data for plural times.

Abstract: Upon a receipt of an advance notice, an active system computer on which asynchronous replication is performed with a standby system computer stops a business application and transmits to the standby system computer transmission start information indicating start of data synchronization, data accumulated in a transmission queue 118, and transmission completion information indicating completion of the data synchronization in this order. The standby system computer generates and holds first reliability guarantee information indicating that the data received before the transmission start information upon a receipt of the transmission start information, and generates and holds second reliability guarantee information indicating that the data received before the transmission completion information is reliable data upon a receipt of the transmission completion information.

Abstract: A computer node connected with an upstream computer node and a downstream computer node so as to be capable of communicating therewith has a replication file system of a master file system, a storing unit, and a controlling unit. The controlling unit receives incremental data showing a changed part of the master file system from the upstream computer node, stores the incremental data into the storing unit, reflects the incremental data on the file system, and transfers the incremental data to the downstream computer node. Moreover, in a case that incremental data for plural times having received from the upstream computer node and having not transferred to the downstream computer node yet are accumulated in the storing unit, the controlling unit merges, with last received incremental data among the incremental data for plural times, the rest of the incremental data for plural times.