Patent ID: 8239621

Claim:
A distributed data storage system for splitting content-data into a plurality of split data and storing a plurality of copy data corresponding to at least one of the plurality of split data in a plurality of memory devices, the system comprising: a copy number planner configured to determine a number of copies for each of the split data based on a system situation including at least one of a demand for the content-data, a predicted demand for the content-data, and an available number of the split data; a copying management information storing unit for storing copying management information indicating a storage location of the copy data corresponding to the split data; an access location determining unit for determining at least one of the plurality of memory devices storing the copy data corresponding to the split data as an access location for accessing split data; and a split data manager for dividing content-data into a plurality of split data and determining a plurality of memory devices as storage locations of a plurality of copy data corresponding to at least one of the plurality of split data, wherein the access location is determined so that the copy data and the corresponding split data are stored in different memory devices, and so as to reduce correlation between the memory devices; the copying management information storage unit stores copying management information indicating the storage locations of the plurality of copy data determined by the split data manager; the split data manager determines assignment locations of copy data so as to uniformize the share numbers of combinations of memory devices, the share number being the number of copy data corresponding to same split data shared by two memory devices; when determining an assignment location of copy data while the assignment location of copy data corresponding to the same split data is already determined, the split data manager determines the memory device showing the smallest share number when combined with the memory device already determined as assignment location of the copy data out of the memory devices except the memory device already determined as assignment location; and the split data manager determines the assignment locations of copy data using a table that shows a two-dimensional arrangement n×n memory devices.