Data storage apparatus, recording medium and method for selectively duplicating data blocks to another medium based on data block size and dimension information or an axis of obtaining data

摘要

A processor controls a second storage device including a plurality of media that store data stored in a first storage device. The processor calculates a ratio of the size of each of a plurality of data blocks, which are classified according to a plurality of pieces of dimension information in data stored in two or more of the plurality of media, to the amount of data stored in the two or more of the plurality of media. The processor determines, based on a calculated ratio, whether a data block is to be duplicated, generates a duplicate of the data block determined to be duplicated, and stores the generated duplicate of the data block into another medium of the plurality of media, except for the two or more media. This can reduce the number of times of changing a medium, and suppress a lowering in the capacity efficiency. Dimension information may be an axis of obtaining data. In additionally disclosed embodiments, data may be arranged based on data blocks originally generated for reliability and considering the axis of obtaining data, and data at an end portion of a medium may be redundantly stored in the front or top portion of a subsequent medium.