| 摘要 |
PROBLEM TO BE SOLVED: To provide a data storage system which provides the advantages of a synchronous mode and an asynchronous mode, i.e, enables primary (P) and secondary (S) systems to be placed far apart without loosing data, by solving the problem, wherein if the P system goes down, data is possibly lost since a P VOL and an S VOL do not maintain the same data at all times during the asynchronous mode. SOLUTION: Primary storage subsystems (SSs) synchronously send write data to an intermediate SS. Upon receiving the write data, the intermediate SS generates control data designating the write order. A portion of the control data, e.g., a sequence number, is generated and attached to the control data of the write data. The intermediate SS sends the write data along with its control data to the secondary SSs asynchronously. The secondary SSs store the write data to the secondary volumes based on the control data. The write order is maintained using the sequence number generated by the intermediate SS. COPYRIGHT: (C)2006,JPO&NCIPI
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