Patent ID: 7020668

Claim:
A data storage device in an information equipment, comprising: a data storage unit storing a plurality of files each having a plurality of attributes; a rule setup unit storing a ranking rule for ranking the files for each of the attributes; an assignment unit assigning reduction ranking to each of the files on the basis of ranking rules associated with the attributes; a reduction unit reducing data in each file according to the reduction ranking when a storage capacity of the data storage unit is insufficient for new data storage; and a data reduction speed storage unit storing data reduction speed for each of a plurality of combinations of a reduction processing algorithm and a file whose data is to be reduced, and wherein the reduction unit calculates a target reduction speed and makes a comparison between the target reduction speed and the data reduction speed stored in the data reduction speed storage unit to determine a combination of a reduction processing algorithm and a file whose data is to be deleted, wherein the rule setup unit further stores application ranking of each of the ranking rules associated with the attributes, and the assignment unit applies the ranking rules in the application ranking order to determine the reduction ranking of the files.