| 摘要 |
PURPOSE:To shorten the useless waiting time for revolutions of a disk and to realize a high-speed input/output system for disk file, by processing the inside areas of the extents of data sets allocated for each track after regarding that these inside areas are partly allocated for each cylinder. CONSTITUTION:For the data sets allocated on a direct access volume for each track in a range between a cylinder (n) and a cylinder (n+3), an range e0 is divided into three areas e1-e3. These areas are stored in a control block as three extents. In this case, both areas e1 and e3 are controlled on the premise that they are allocated for each cylinder. Thus it is not required to decide an extent termination for each track boundary during the processing of cylinders (n+1)-(n+2) and therefore the useless waiting time is shortened for revolutions of a disk. Then the file input/output processing is carried out at a high speed.
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