| 摘要 |
PURPOSE:To remove I/O operation to an unnecessary disk device by forming a buffer control information referring means for selecting a buffer having the lowest residence degree in a buffer control information area while referring the residence degree when the buffer is newly required. CONSTITUTION:A buffer control information area 21 stores a numeral indicating the residence degree of each buffer 14 and the contents of the area 21 are set up and updated by a buffer control information updating means 22 and referred by the buffer control information referring means 23. The updating means 22 sets up the residence degree of the buffer in the area 21. The residence degree of the buffer is set up to '0' at a time when the contents of a record in a virtual disk device are entered to the buffer 14 and then updated. When the contents of an accessed track do not exist in any buffer 14 and a new buffer is required, the means 23 selects a buffer having the lowest residence degree out of the plural buffers 14.
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