RAID DEVICE

PROBLEM TO BE SOLVED: To provide a RAID device capable of restoring data of the latest cache without losing in an RAID device having a doubled RAID controller even if both the systems are stopped due to a hardware trouble. SOLUTION: The structure management part of an RAID controller 1 retains information showing which of the doubled systems newer cache data are present in. When both the systems of the RAID controller 1 are stopped, a monitoring control part 6 which detects this executes the power supply ON/OFF processing of both the systems of the RAID controller 1 to restart the RAID controller 1. The hardware trouble which temporarily occurred is restored by this restart, and in the restarting, a proper cache memory is selected in reference to the information retained in the structure management part 5 to perform the rewriting processing of the cache data to the disk. COPYRIGHT: (C)2004,JPO&NCIPI