STEUERVERFAHREN FUER EINGABE/AUSGABEEINHEITEN

摘要

In an input/output (I/O) scheduling method wherein I/O units (14) perform pre-processes of fixed time interval off-line from a controller (13) before data transfer processes, wherein a plurality of blocks are prefetched/postwritten between the I/O units and a buffer (21) disposed within the controller, and wherein a schedule process for determining a prefetch/postwrite data amount and a prefetch/postwrite data transfer start time of one I/O unit is executed at one schedule point, a next 28 schedule point is set to be earlier by the pre-process time interval than a time at which a prefetch/postwrite data transfer process scheduled at a present schedule point ends, and whether the transfer process of the I/O unit scheduled at the present point is executed or that of another I/O unit is executed is further determined depending upon an operating situation at the next schedule point. Allowance is thus made for e.g. the (off-line) start/stop/repositioning intervals of magnetic tape units. <IMAGE>