Patent ID: 8578206

Claim:
A disk controller to control a plurality of disk devices to store redundant data distributed there across, the disk devices providing at least one logical volume across the disk devices, the disk devices including a plurality of pool volumes allocatable to one of the logical volumes in accordance with an access from a host to the logical volume, the disk controller comprising: a memory to store information indicating a relationship between the pool volumes and the logical volume, the information used to allocate the pool volumes to the logical volume when a real area of the pool volumes used for the logical volume is not previously allocated to a logical volume before a host makes a request; and a processor to perform data reconstruction in accordance with a failure of the disk devices, a process of the data reconstruction including reading data from a plurality of the pool volumes included in the other disk devices, the processor configured to execute: detecting an error in a part of the pool volumes included in the other disk devices when the processor reads data from the pool volumes; determining whether the pool volume in which the error is detected is allocated to the logical volume or not in reference to the information; and formatting the part of the pool volume in which the error is detected when the pool volume in which the error is detected is unallocated to the logical volume in accordance with the information.