Patent ID: 8762643

Claim:
A control method of a disk array apparatus having first and second control modules, and a disk array for storing data which is written or read by the first and second control modules, the control method comprising: controlling, by a first processor in the first control module, a first cache memory, a first battery that supplies electric power to the first cache memory during an electric power failure of a main power supply for the disk array apparatus, a first memory controller that writes data in the first cache memory, and a first nonvolatile memory to which the data of the first cache memory is saved; controlling, by a second processor in the second control module, a second cache memory, a second battery that supplies electric power to the second cache memory during an electric power failure of the main power supply for the disk array apparatus, a second memory controller that writes data in the second cache memory, and a second nonvolatile memory to which the data of the second cache memory is saved; acquiring, by the first processor of the first control module, second system state information describing a state of the second battery and a state of the second nonvolatile memory and indicating whether data may be saved from the second cache memory to the second nonvolatile memory; and determining, by the first processor of the first control module, based on combination of the acquired second system state information and first system state information of the first control module, whether the disk array apparatus is set in a write-back state or a write-through state, the first system state information describing a state of the first battery and a state of the first nonvolatile memory and indicating whether data may be saved from the first cache memory to the first nonvolatile memory.