Patent ID: 6643750
Filing Date: 2003-11-04
Classification: G06F,Y10S

Abstract:
For use in an information processing system including a host computer, a main storage apparatus, and a sub storage apparatus in data communication with the main storage apparatus, a method to back up data from the main storage apparatus to the sub storage apparatus, comprising steps of:sending, from the host computer to the main storage apparatus, an instruction to maintain firs data stored in a first storage area of the main storage apparatus; in response to the instruction, transferring the first data to the sub storage apparatus; if during transferring the main storage apparatus receives second data from the host computer for updating corresponding data stored in the first storage area and the corresponding data has been already transferred to the sub storage apparatus, then storing the second data into the first storage area; if the corresponding data has not been transferred to the sub storage apparatus, then storing the second data into a second storage area of the main storage apparatus; transferring the second data into a third storage area in the sub storage apparatus; after completion of transferring the first data and transferring the second data, communicating a first signal from the main storage apparatus to the sub storage apparatus indicative of the completion; and in response to the first signal, copying data stored in the third storage area to a fourth storage area in the sub storage apparatus.