Patent ID: 8433882

Claim:
A disk array control device adapted to manage a plurality of drives as a single logical drive, the disk array control device being coupled to a host via a first interface operating in accordance with a first standard and coupled to the plurality of drives via a plurality of second interfaces each operating in accordance with the first standard, comprising: a first register configured to store a value designated by the host, the value indicating a destination device to which a predetermined command is to be passed, the predetermined command being used for maintenance of the disk array control device or maintenance of at least one of the plurality of drives, the destination device being either the disk array control device or any one of the plurality of disk drives, an initial value of the value stored in the first register indicating the disk array control device, wherein the value stored in the first register is set to the initial value when the first register is cleared; and a control module configured to (i) receive a command from the host, (ii) determine whether the received command is the predetermined command, (iii) execute a RAID control process for executing a data read among the plurality of drives if the received command is a data read command or a data write among the plurality of drives if the received command is a data write command, (iv) perform, in a case where the received command is the predetermined command and the value stored in the first register indicates one of the plurality of drives, a pass-through process of sending the received command which is the predetermined command to the one of the plurality of drives, and (v) execute the predetermined command in order to perform an operation for maintenance of the disk array control device in a case where the received command is the predetermined command and the value stored in the first register indicates the disk array control device.