| 摘要 |
PROBLEM TO BE SOLVED: To provide new virtual storage control technology for achieving data maintenance for data to be successively updated according to the lapse of time. SOLUTION: Write request data are written in an empty block owned by a virtual disk for data maintenance whose unauthorized access or erroneous operation is never operated, and when rewriting has been performed and what kind of rewriting has been performed to the virtual disk according to the write request data is recorded in a rewriting information storage means, and when the data restoration request of the virtual disk is made by designating the point of time of the virtual disk, the data of the virtual disk at that point of time are read from the virtual disk for data maintenance based on the information of the rewriting information storage means so that the data of the virtual disk at that point of time can be restored. Thus, it is possible to achieve the data maintenance for the data to be successively updated according to the lapse of time. COPYRIGHT: (C)2008,JPO&INPIT
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