Abstract: A storage apparatus includes a storage unit configured to include a plurality of tiers, a group management unit configured to manage files stored in any of the tiers in the storage unit by dividing the files into a plurality of groups, a movement target selection unit configured to select a group, out of the groups, which satisfies a tier movement condition as a movement target of the tier, and a file movement unit configured to move a subordinate file belonging to the group selected by the movement target selection unit, from a tier in which the subordinate file is stored to another tier.

Abstract: When a master name node has created a file, the master name node performs meta-information synchronization with only a slave name node, and does not perform the meta-information synchronization with a dummy name node. The master name node performs the meta-information synchronization with the dummy name node asynchronously with file creation. Furthermore, the slave name node stores the same meta-information as that stored in the master name node, and the file is stored in a data node placed in the same node as the slave name node and a data node placed in the same node as the master name node.

Abstract: A storage apparatus is disclosed, including a first storage area, a second storage area, and a controller. The controller writes data to the first storage area based on a write request. When the data are written in the first storage area, the controller sequentially writes the data to the second storage area from a beginning of a physical address thereof. The controller outputs the data to a backup apparatus by sequentially reading out the data being written in the second storage area from the beginning of the physical address.

Abstract: A disc array device for maintaining consistency of data. When write processing is interrupted and then restarted, new data may be stored in a nonvolatile memory and regeneration of parity may be impossible because data can not be read out normally from a disc device other than a disc device in which new data is to be written and a disk device for parity. In such a case, a special write executing unit overwrites the new data stored in the nonvolatile memory at a specified write position of the disk device in which new data is to be written.

Abstract: When write processing once interrupted is restarted, if new data is stored in a nonvolatile memory 34 and regeneration of parity is impossible because data can not be read out normally from a third disk device (for instance 32-2) other than a disk device (for instance 32-1) in which new data is to be written and a disk device (for instance 32-5) for parity, a data writing unit 113 in a special write executing unit 110 overwrites the new data stored in the nonvolatile memory 34 at a specified write position of an appropriate disk device (for instance 32-1).

Abstract: A disk control device is operationally connected to a high-order device and operates a plurality of disk devices. A cache is included in the disk control device for storing data including a plurality of parity data from a corresponding plurality of parity groups in the plurality of disk devices. The disk control device also includes a cache management table for indicating the positions of the data stored in the cache. Cache management means is provided for transferring a selected data request by the host control from the plurality of disk devices to the cache when the cache management table indicates that said selected data is not stored in the cache. Control means transfers the selected data from the cache to the high-order device when the cache management means informs the control means that the selected data is stored in the cache.

Abstract: In a device array system, a failure alternate device is fetched from another logic group of a higher redundancy without needing a hot spare patrol, accordingly recovering redundancy of data. In a case corresponding to a mirrored device of RAID-1, as a logic group of a device array unit, a construction control unit constructs a first logic group in which the same data is stored into (N=2) devices and duplicated and a second logic group in which the same data is stored into (N+1=3) devices and triplicated. when one device has failed in the first logic group having a lower redundancy and the redundancy is lost, a failure processing unit fetches one device from the second logic group of a higher redundancy into the first logic group and reconstructs data by using the fetched device as a failure alternate device, accordingly recovering the redundancy of the first logic group.