In a computer for executing processing based on a storage management program, a management information storing unit designates, from the data blocks having the same content, main-data used as an access destination and sub-data used as a backup, and stores management information that registers storage nodes as allocation destinations of the respective main-data and sub-data; a load information collecting unit continuously collects load information on the storage nodes; a replacement object detecting unit detects a pair of the main-data and the sub-data having the same content and having a predetermined condition such that a load difference between the allocation destination of the main-data and that of the sub-data exceeds a predetermined allowable value; and a management information updating unit replaces roles of the main-data and the sub-data between the detected pair of data blocks.