| 摘要 |
PROBLEM TO BE SOLVED: To efficiently generate a remote copy through the use of a snapshot function. SOLUTION: As shown in A, conversion is performed from data for the snapshot into the first bit map of difference data for the remote copy. The conversion is preliminarily performed in a proper period. The second bit map of cascade difference data of the new differential data is generated simultaneously with the generation of the data for the snapshot as showed in B in the case of splitting the snapshot function. The second bit map of the cascade differential data is generated in a form being the same as that of the first bit map of the differential data for the remote copy. In the case of transition from the split state to pair state of the snapshot function as showed in C, the second bit map of the cascade differential data is added (OR) to the first bit map of the difference data for the remote copy so as to generate the remote copy, on the basis of the added bit maps. COPYRIGHT: (C)2005,JPO&NCIPI |
