Storage system making possible data synchronisation confirmation at time of asynchronous remote copy

摘要

A synchronization confirmation method required for operation of a database is provided to a host device (1a) connected to a disk device which provides remote asynchronous data transfer. Immediately after commit of write data, an application (2a) of the host device (1a) issues a sync command which requires synchronization confirmation. A disk control device (130a) notifies the host device (1a) of a number (204) concerning latest data received from the host device of a local side and a number (206) concerning latest data received by a remote side. When the two numbers have coincided with each other, the host device judges the commit operation to have been completed.