Abstract: In a disk array system, multiplexed clusters and multiplexed power source units for supplying power sources to the respective clusters are arranged. Each cluster has a power failure judging unit for judging the power source condition of other cluster. In response to a case where one cluster stops its operation first owing to a power failure, at the power failure, for example, MP of the cluster blocks the portion of the other cluster, and judges the power source condition of the other cluster on the basis of a signal from the power failure judging unit, and records power failure information showing the power source condition to a memory. At power recovery, if the cluster recognizes that the portion in blocked condition of the other cluster is in blockage owing to the power failure, the cluster recovers the portion.

Abstract: A storage system is configured so that it can operate based on an operation mode set by an administrator from among a memory backup mode, a destage mode, a UPS mode, and a remote copy mode. The administrator can select the operation mode according to the battery capacity of the battery module, making it possible to provide a highly-convenient storage system.

Abstract: In a disk array system, multiplexed clusters and multiplexed power source units for supplying power sources to the respective clusters are arranged. Each cluster has a power failure judging unit for judging the power source condition of other cluster. In response to a case where one cluster stops its operation first owing to a power failure, at the power failure, for example, MP of the cluster blocks the portion of the other cluster, and judges the power source condition of the other cluster on the basis of a signal from the power failure judging unit, and records power failure information showing the power source condition to a memory. At power recovery, if the cluster recognizes that the portion in blocked condition of the other cluster is in blockage owing to the power failure, the cluster recovers the portion.

Abstract: A disk array device having two or more disk units, each disk unit including at least one disk drive, at least either of said disk units having parity bits carrying data recovery information, comprises at least one backup battery provided for each of said disk unit.

Abstract: An object of the invention is to make it possible to secure data retained by a cache memory with high reliability without increasing the size or cost of a storage device. When a host-handling processor and a disk processor have recognized occurrence of a power failure, operation of a storage device is continued for about one minute on DC power that is supplied from a battery module. After a lapse of one minute from the occurrence of the power failure, the host-handling processor interrupts the connection between the storage device and a host. Then, the host-handling processor turns off a SW of a host I/F and the disk processor writes, to an HDD, data that have been written to a cache memory. After completion of this processing, the disk processor turns off a SW of the disk I/F and a SW of the HDD. Then, the disk processor causes the battery module to supply DC power only to the cache memory.

Abstract: An object of the invention is to make it possible to secure data retained by a cache memory with high reliability without increasing the size or cost of a storage device. When a host-handling processor and a disk processor have recognized occurrence of a power failure, operation of a storage device is continued for about one minute on DC power that is supplied from a battery module. After a lapse of one minute from the occurrence of the power failure, the host-handling processor interrupts the connection between the storage device and a host. Then, the host-handling processor turns off a SW of a host I/F and the disk processor writes, to an HDD, data that have been written to a cache memory. After completion of this processing, the disk processor turns off a SW of the disk I/F and a SW of the HDD. Then, the disk processor causes the battery module to supply DC power only to the cache memory.

Abstract: A disk array device having two or more disk units, each disk unit including at least one disk drive, at least either of said disk units having parity bits carrying data recovery information, comprises at least one backup battery provided for each of said disk unit.