Abstract: A storage apparatus includes: storage modules for storing data, each of the data including meta data for identifying an attribute of the data, each of the storage modules having a characteristic different from one another; a memory for storing information of the characteristic of each of the storage modules; and a controller for controlling the storage modules so as to optimize allocation of the data among the storage modules, including: a receiving module for receiving external information having meta data and condition information, a selecting module for selecting data having meta data corresponding to the meta data included in the external information among data stored in the storage modules, a determining module for determining a storage module having a characteristic optimum for the condition information, and a updating module for updating location of the selected data so as to be stored in the determined storage module.

Abstract: A file control device having physical storage devices and logical storage devices, which prevents competition for access to the physical storage device and avoids a decline in performance. When adding a new block to the cache memory or when ejecting a block from cache memory, a block with the lowest access frequency out of data retained in a physical storage device having the lowest access frequency is determined for ejection. The file control device concurrently monitors storage device priority information in addition to data priority information to control transfer of data between the storage device and the cache memory.

Abstract: A parity which is used to a disk array is formed by using a cache memory. A storing method of the cache memory is classified into three methods such that: only data is stored; only redundant information is stored; and both of the data and the redundant information are stored. Even when a power source is shut off during the data writing process, the processing stages of the data writing and parity updating and the necessary data are stored into a non-volatile memory and are used for recovery.

Abstract: A parity which is used to a disk array is formed by using a cache memory. A storing method of the cache memory is classified into three methods such that: only data is stored; only redundant information is stored; and both of the data and the redundant information are stored. In order to save processing time, a new set of redundant information (or parity data) is not calculated for every data update. Instead, the new parity data is only calculated after there have been a predetermined number of data updates. In addition, even when a power source is shut off during the data writing process, the processing stages of the data writing and parity updating and the necessary data are stored into a non-volatile memory and are used for recovery.