Disk array device and maintenance method for disk array device

A disk array comprising:

• channel adapters which control exchange of data with host apparatuses;
• disk adapters which control exchange of data with storage devices;
• cache memory packages which are used by the channel adapters and the disk adapters and have cache memories storing data;
• first control memory packages which are used by the channel adapters and the disk adapters and have first control memories storing management information which is used for controlling the operation of the disk array device;
• and
• second control memory packages which are used by the channel adapters and the disk adapters and have second control memories storing storage structure information with regard to a storage structure of the cache memory,
• wherein the management information is stored in the first control memories, respectively, and multiplexed, and at least one maintenance control unit which, in the case in which a failure has occurred in one of the second control memories, restores the storage structure information stored in the second control memory in which the failure has occurred,
• wherein the maintenance control unit restores the storage structure information stored in the second control memory, in which the failure has occurred, using a storage area of the first control memories, and
• wherein the maintenance control unit executes at least one of (1) a first maintenance mode which is executable in the case in which no usable free space exists in the first control memories, (2) a second maintenance mode which is executable in the case in which a usable free space exists as a predetermined value or more in the first control memories, and (3) a third maintenance mode which is executable in the case in which a usable free space exists as less than the predetermined value in the first control memories, and
• (1) the first maintenance mode is a mode for,
• (1-1) in the case in which a failure has occurred in one of the first control memories, if the first control memory, in which the failure has occurred, has been replaced with a normal product, restoring the management information by copying the management information multiplexed in the other first control memories to the replaced the first control memory, and
• (1-2) in the case in which a failure has occurred in the second control memory, reestablishing the storage structure information overwriting the storage structure information on the first control memory, and
• if the second control memory, in which the failure has occurred, has been replaced with a normal product, reestablishing the storage structure information in the replaced second control memory, and
• restoring the management information by copying the management information multiplexed in the other first control memories to the first control memory on which the storage structure information has been overwritten,
• (2) the second maintenance mode is a mode for,
• (2-1) in the case in which a failure has occurred in one of the first control memories, if the first control memory, in which the failure has occurred, has been replaced with a normal product, restoring the management information by copying the management information multiplexed in the other first control memories to the replaced first control memory, and
• (2-2) in the case in which a failure has occurred in the second control memory, reestablishing the storage structure information in a free space of the first control memory, and permitting replacement of the second control memory, in which the failure has occurred, with a normal product, and
• (3) the third maintenance mode is a mode for,
• (3-1) in the case in which a failure has occurred in one of the first control memories, if the first control memory, in which the failure has occurred, has been replaced with a normal product, restoring the management information by copying the management information multiplexed in the other first control memories to the replaced first control memory, and
• (3-2) in the case in which a failure has occurred in the second control memory, partly reestablishing the storage structure information by a range which can be reestablished in a free space of the first control memory, and
• if the second control memory, in which the failure has occurred, has been replaced with a normal product, reestablishing a remaining part, which is not reestablished, of the storage structure information in the replaced second control memory.