1. Field
One embodiment of the present invention relates to a disk array control device which manages a plurality of drives as a single logical drive, and a storage device including the disk array control device.
2. Description of the Related Art
In recent years, in an information processing apparatus such as a server or a personal computer, use is made of a disk array control system such as a redundant array of inexpensive disks (RAID).
The disk array control system is a system which handles a plurality of drives, such as hard disk drives, as a single logical drive. In the disk array control system, data is distributively written in a plurality of drives in units of a data block. Accordingly, the performance of data write and read can be improved.
Jpn. Pat. Appln. KOKAI Publication No. 2007-188372 discloses a disk array controller which controls an array disk that comprises a plurality of disk drives. In order to make it possible to update the firmware of each disk drive, the disk array controller includes a memory module which stores a flag designating whether the plural disk drives are used as an array disk or are used as unit disk drives. In the case where the flag is “1”, the disk array controller executes a process for array-controlling the plural disk drives. On the other hand, in the case where the flag is “0”, the disk array controller enables a system apparatus to access each disk drive as a unit disk drive.
In the disk array controller of Jpn. Pat. Appln. KOKAI Publication No. 2007-188372, however, in the case where the flag is “0”, no process for array control is executed, and all commands from the system, which include data read/write commands, are directly sent to a certain disk drive. Thus, if the flag is set to “0” during the operation of the system in which the plural disk drives are array-controlled, the data structure, which is constructed on the array disk, may possibly be destroyed. Consequently, it is practically difficult to update the firmware during the operation of the system.
Therefore, it is necessary to realize a novel function which can execute a process relating to the maintenance of each of the drives even in the state in which the operating system is running.