PROBLEM TO BE SOLVED: To improve an efficiency for applying a data transfer function such as a remote copy to data.SOLUTION: Improvements of the network efficiency for the remote copy are to: receive from a host computer, a data write input/output (I/O) command including an application ID that identifies an application for transmitting a write I/O request and operating on a host computer; retain a record of a relationship between the application ID in the write I/O command and a storage location of the data to be written in a first volume of a storage system; determine, based on the application ID, whether a data transfer function between the first volume and a second storage volume is to be performed on the data beyond writing the data to the storage location in the first volume; and if the data transfer function is to be performed on the data, then perform the data transfer function on the data to the second volume.