Compositions and methods for reducing the rate of loss of oxygen from a solution and increasing the effective life span of oxygen-containing calibration solutions. The method includes dividing control information into two or more portions, each portion being associated with a unique control sequence number. The backup processing is performed by distributing each of the file data in the file data group to the backup data holding area in turn from a least backup data holding area where a file data being currently stored is least among the matching nodes.