Patent ID: 7047256

Claim:
A storage system, for use in a computer system having a plurality of host devices and a plurality of said storage systems, for receiving write-in data from at least one of the host devices, said storage system comprising: a physical storage device having a logical volume for storing data, wherein said storage system is controlled so that identical data is saved across a plurality of storage systems; a device for saving a time of reception on which write-in data was received from a host device in a data consistency holding table; wherein said data consistency holding table includes a plurality of entries each indicating a corresponding relation between a reception time of write-in data, an identifier of a host which sent the write-in data to said storage system, an address at which the write-in data is to be stored, an identifier of a storage system in which the write-in data is stored and an address in a temporary storage device within which the write-in data is temporarily stored; a communication interface device for conducting bi-directional transmission of write-in data including transmitting write-in data addressed to the logical volume and a corresponding reception time to another storage system and receiving write-in data addressed to the logical volume and the corresponding reception time from the another storage system; and a data consistency holding control device for effecting control, based on said data consistency holding table, to write write-in data which was received from the host device and write-in data which was received through the communication interface device into the physical storage device after such write-in data has been made to wait in the temporary storage device for more than a predetermined time as measured from the reception time corresponding to the write-in data to the logical volume, so that, when write-in data which was received from the host device and write-in data which was received through the communication interface device are written in an overlapped manner into the same storage location of the physical storage device, they are written in an order as indicated by their respective reception times.