| 摘要 |
PROBLEM TO BE SOLVED: To obtain an effect of enhancement of performance by a log structured data writing method simply by preparing a minimum memory and idle area. SOLUTION: This disk controller 12 controls disk devices 110-0, 110-1 in which plural identifiable logical disks are allocated from a host computer 20 and the smaller number of buffer areas than the plural logical disks are allocated. The disk controller 12 secures unused buffer areas and switches the disk controller to the log mode in which an area formed by integrating an area on the disk device to which a specified logical disk is allocated and a secured buffer area is used as a data storage area when switching of the logical disks from use in a normal mode to the use in a log mode is instructed from the host computer 20. In addition, a corresponding buffer area is released from the logical disk when the logical disk in the log mode is switched to the use in the normal mode.
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