| 摘要 |
PROBLEM TO BE SOLVED: To reduce a resource for a disk prepared as a hot spare. SOLUTION: A plurality of physical disks are managed as one logic disk, or one portion of an area in the one physical disk is managed as one logic disk, to realize a RAID function using the logic disk. Data restoration processing is allowed to be executed by this constitution when total disk capacity prepared as the hot spare is larger than trouble-generated disk capacity, even when the hot spare of capacity same to the trouble-generated disk capacity or more is not prepared. When data restorations are required at the same time by the plural RAIDs, the data restoration processing is allowed to be executed when total restored data capacity is smaller than the disk capacity prepared as the hot spare, even when only one hot spare is prepared.
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