A storage controller for a storage system in which there are multiple storage devices and a method for recording diagnostic information are provided. The storage controller includes a storage device manager which has means for allocating a storage device in the storage system for storing diagnostic data. The storage controller also includes means for generating diagnostic data regarding the operation of the storage controller. Two buffers are used for alternately recording and writing batches of diagnostic data to the allocated storage device. The allocated storage device may be a storage device which is normally reserved for disaster recovery in the storage system.
A disk array device has: a CM separating part that, when abnormality occurs in a CM, separates the CM in which the abnormality has occurred from a storage system after write of CM operation information data to a hard disk is completed; and communication path reconfiguring parts that reconfigure communication paths between the CM in which the abnormality has occurred and DAs. When abnormality occurs in the CM, the communication paths between the CM and the DAs are reconfigured, and after the CM operation information data of the CM is written to the hard disk, the CM is separated. Therefore, the write processing is not interrupted halfway, so that the useful operation information data regarding the cause of the problem occurrence can be written to the hard disk having a sufficient storage area.
