Information storage system

An information storage system comprising a control unit for receiving a data write request from another information storage system and a storing unit connected to said control unit,

• said control unit further comprising a control module for comparing a time difference between the latest write time among write time of the write data transferred from another information storage system and the write time of write data which has been copied at last among the transferred write data with a preset allowance time and regulating the data write request when the time difference exceeds said allowance time.

An information storage system comprising a master control unit for receiving a data write request from an information processor, a storing unit connected to the master control unit, a remote control unit to which the write data is transferred from said master control unit, and a storing unit connected to said remote control unit,

• wherein said master control unit has a control module for comparing a time difference between the latest write time and the oldest write time in a group of pending write data, which has been write completion reported to said information processor, to be transferred to said remote control unit with a preset allowance time and regulating new data write requests from said information processor when the time difference exceeds said allowance time,
• wherein the write completion reports to the information processor and the regulating new data write requests from the information processor occur a synchronously and independently of each other.

A data transfer method of an information storage system comprising a master control unit for receiving a data write request from an information processor, a storing unit connected to said master control unit, a remote control unit to which the write data is transferred from said master control unit, and a storing unit connected to said remote control unit,

• wherein said master control unit compares a time difference between the latest write time and the oldest write time in a group of write data which has been write completion reported to said information processor and has not been transferred but should be transferred to said remote control unit as a destination of the write data with a preset allowance time and regulates new data write requests from said information processor when the time difference exceeds said allowance time,
• wherein the write completion reports to the information processor and the regulating new data write requests from the information processor occur a synchronously and independently of each other.

An information storage system comprising a control unit for receiving a data write request from an information processor and a storing unit connected to said control unit,

• said control unit further comprising a control module for comparing the number of data which has been write completion reported to said information processor and has not been copied to said other information storage system with a preset data pending allowance number and regulating new data write requests from said information processor when said number of data exceeds said data pending allowance number,
• wherein the write completion reports to the information processor and the regulating new data write requests from the information processor occur a synchronously and independently of each other.