Prestaging method, buffer management method and file system

Abstract

A prestaging method is adapted to a computer system comprising a central processing unit, a buffer and a secondary storage, where the prestaging method reads input data of a submitted job into the buffer from the secondary storage before executing the submitted job so as to carry out a prestaging. The prestaging method includes the steps of (a) obtaining a number of jobs for which prestagings are to be carried out simultaneously as the prestaging for the submitted job, (b) obtaining an effective data transfer speed based on the number of jobs and a data transfer speed of the secondary storage which stores the input data of the submitted job for which the prestaging is to be carried out, and (c) setting a prestaging start time from which the prestaging for the submitted job is to start by subtracting an effective data transfer time from a scheduled job start time from which the submitted job is to start, where the effective data transfer time is defined as a time which is obtained by dividing an amount of the input data by the effective data transfer speed.