Patent ID: 6816981
Filing Date: 2004-11-09
Classification: G06F

Abstract:
A disk array device comprising:a subsystem control module comprising a memory backed up with a battery; disks; and a device control module controlling said disks and comprising a buffer storing redundant data, wherein when data is to be written to said disks, the disk array device allocates and writes the data to the respective disks, generates redundant data from said allocated data and corresponding to said allocated data, and writes said redundant data onto disks of said disks not storing the corresponding allocated data, and wherein when writing data to said disks, the data written to the memory of said subsystem control module is held until a writing process is completed and when at least one of said disks is broken or degenerated, the disk array device transfers and stores the redundant data stored in the buffer of the device control module to the memory of the subsystem control module, wherein the subsystem control module instructs the device control module to be in a first mode if the disks are in a normal state, a second mode if at least one of the disks is in a degeneration state, a third mode upon restoration of power after an unexpected loss of power while writing and the at least one of the disks is not in a degeneration state, and a fourth mode upon restoration of power after an unexpected loss of power while writing and the at least one of the disks is in a degeneration state.