Patent ID: 8364890

Claim:
A RAID control apparatus comprising: a plurality of disk devices; and a plurality of disk control devices, wherein each of the disk control devices includes a cache memory that stores cache data of a logical unit and at least one of the disk control devices accesses a plurality of logical units in different disk devices of the plurality of disk devices being concatenated to each other, transfers management information of the cache data of the logical unit to be moved to another one of the plurality of disk control devices that is in charge of access to the plurality of concatenated logical units when a logical unit, of which one of the plurality of disk control devices is in charge, is moved to the another one of the plurality of disk control devices is in charge, is moved to the another one of the plurality of disk control devices, and transfers the cache data of the logical unit to be moved from the disk control device to the another disk control device when an I/O request is received from a host computer, without writing back the cache data stored in a cache memory of the disk control device that controls a source disk of the plurality of disk devices, to the source disk device.