| 摘要 |
PURPOSE:To contrive to improve the storage efficiency of data by setting a flag for showing whether a size is to be reduced or not at every data file, and eliminating an unused area with regard to the data file whose size is to be reduced, by referring to the flag, when the unused area is detected at the time of data compression processing. CONSTITUTION:Use areas of data files 3, 4, 6 and 8 of a file volume 1a before the processing are denoted as 3a, 4a, 6a and 8a, and their unused areas are denoted as 3b, 4b, 6b and 8b, and to a directory part 2, a flag part 2a for discriminating whether a reduction of a size of the files 3, 4, 6 and 8 is to be executed or not is set by a flag control means 11. In this state, when it is detected that a data to be compressed, of the volume 1a remains behind, by a file processing means 10, its information is read from the directory part 2. Also, when it is necessary to reduce the size, a reduction processing is executed with regard to the areas 3b, 4b, 6b and 8b, and idle areas 5, 7, and by executing a transfer and a front justification of its file, information is written in the directory part 2.
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