Multiple data management method, computer and storage device therefor

A multiple data management method in a system in which a host computer and primary and secondary storage devices are connected as capable of communicating with each other via a network, said primary and secondary storage devices functioning as data storage of said host computer, said method comprising:

• transmitting, by said host computer, data to be written and a write request Wa to said primary storage device in writing of data into said primary storage device and transmitting, by said host computer, said data to be written and a write request Wb to said secondary storage device at any point in time after said foregoing transmission;
• storing said data to be written by said primary storage device upon receipt of said write request Wa;
• storing said data to be written by said secondary storage device upon receipt of said write request Wb;
• wherein said data transmitted by said host computer to said secondary storage device is not received from said primary storage device by said host computer;
• said host computer attaching a serial number to said write request Wb transmitted to said secondary storage device, said serial number being given in an order of said transmission of said write requests Wb;
• said secondary storage device storing said serial numbers attached to said write requests Wb, monitoring whether or not there is any missing serial number and, when a missing serial number is detected, transmitting to said host computer a data retransmission request of said data to be written corresponding to said missing serial number;
• upon receipt of said data retransmission request, said host computer transmitting a transmission request of said data to be written to said primary storage device;
• said primary storage device receiving said data transmission request and transmitting said data to be written to said host computer based on said transmission request;
• said host computer transmitting said data to be written to said secondary storage device upon receipt thereof;
• and
• said secondary storage device storing said data to be written upon receipt thereof.

A data management method in a system in which a host device is connected with a primary storage device and a secondary storage device, the method comprising:

• transmitting, by the host device, data to be written and a write request Wa to the primary storage device in writing of data into the primary storage device;
• transmitting, by the host device, the data to be written and a write request Wb to the secondary storage device at any point in time subsequent to transmitting the same data to the primary storage device;
• wherein the data transmitted by the host device to the secondary storage device is not received from the primary storage device by the host device;
• attaching a serial number to the write request Wb transmitted to the secondary storage device, the serial number being given in an order of transmission of the write requests Wb;
• receiving, by the host device, a data retransmission request of the data to be written corresponding to a missing serial number when the missing serial number is detected amongst the serial numbers received by the secondary storage device;
• and
• upon receipt of the data retransmission request, transmitting the data to be written, by the host computer, to the secondary storage device corresponding to the missing serial number.

A data management method in a system in which a host device is connected with a primary storage device and a secondary storage device, the method comprising:

• transmitting, by the host device, data to be written and a write request Wa to the primary storage device in writing of data into the primary storage device;
• transmitting, by the host device, the data to be written and a write request Wb to the secondary storage device at any point in time subsequent to transmitting the same data to the primary storage device:
• wherein the data transmitted by the host device to the secondary storage device is not received from the primary storage device by the host device;
• attaching a serial number to the write request Wb transmitted to the secondary storage device, the serial number being given in an order of the transmission of the write requests Wb;
• receiving, by the host device, a data retransmission request of the data to be written corresponding to a missing serial number when the missing serial number is detected amongst the serial numbers received by the secondary storage device;
• and
• upon receipt of the data retransmission request, transmitting, by the host device, a transmission request of the data to be written to the primary storage device;
• receiving, by the host device from the primary storage device, the data to be written corresponding to the missing serial number;
• and
• transmitting, by the host device, the data to be written to the secondary storage device upon receipt thereof from the primary storage device.

A data management method in a system in which a host device is connected with a primary storage device and a secondary storage device, the method comprising:

• transmitting, by the host device, data to be written and a write request Wa to the primary storage device in writing of data into the primary storage device;
• storing the data to be written in the host device;
• transmitting, by the host device, the data to be written which is stored in the host device and a write request Wb to the secondary storage device at any point in time subsequent to transmitting the same data to the primary storage device;
• attaching a serial number to the write request Wb transmitted to the secondary storage device, the serial number being given in an order of transmission of the write requests Wb;
• receiving, by the host device, a data retransmission request of the data to be written corresponding to a missing serial number when the missing serial number is detected amongst the serial numbers received by the secondary storage device;
• and
• upon receipt of the data retransmission request, transmitting the data to be written, by the host computer, to the secondary storage device corresponding to the missing serial number.

A data management method in a system in which a host device is connected with a primary storage device and a secondary storage device, the method comprising:

• transmitting, by the host device, data to be written and a write request Wa to the primary storage device in writing of data into the primary storage device;
• storing the data to be written in the host device;
• transmitting, by the host device, the data to be written which is stored in the host device and a write request Wb to the secondary storage device at any point in time subsequent to transmitting the same data to the primary storage device;
• attaching a serial number to the write request Wb transmitted to the secondary storage device, the serial number being given in an order of the transmission of the write requests Wb;
• receiving, by the host device, a data retransmission request of the data to be written corresponding to a missing serial number when the missing serial number is detected amongst the serial numbers received by the secondary storage device;
• and
• upon receipt of the data retransmission request, transmitting, by the host device, a transmission request of the data to be written to the primary storage device;
• receiving, by the host device from the primary storage device, the data to be written corresponding to the missing serial number;
• and
• transmitting, by the host device, the data to be written to the secondary storage device upon receipt thereof from the primary storage device.