1. A computer system comprising: a computer for receiving a request and outputting a result in response to the request; and a storage system for storing data which is output based on the request, the computer including a first processor, a first memory coupled to the first processor, and a first network interface coupled to the first processor, the storage system including a second processor, a second memory coupled to the second processor, a plurality of storage devices coupled to the second processor, each exclusively storing a different category, of one or more categories, of a plurality of pieces of the data, and a second network interface coupled to the second processor, the first memory storing instructions, that when executed by the first processor, cause the first processor to execute: a request reception module for receiving the request; a processing procedure generation module for generating, based on the request, a plurality of processing procedures, each defining an order of access to the one or more categories of data of the plurality of categories, that are each stored in different storage devices, wherein the plurality of processing procedures are different from each other; a data division module for dividing the categorized data stored in the plurality of storage devices; an information obtaining module for obtaining load information including a plurality of loads on the storage devices of the storage system; an allotment determination module for determining, based on the obtained load information, allotments for allocating the divided categorized data to be processed by the generated plurality of processing procedures; and a processing execution module for executing, based on the determined allotments, a subset of a plurality of subsets of the generated plurality of processing procedures according to the order of access to the plurality of pieces of categorized data that are stored in different storage devices, in parallel, wherein the obtained load information further includes a plurality of upper-limit load values representing upper limits for the loads on each of the plurality of storage devices of the storage system, and wherein execution of the allotment determination module programs the first processor to: calculate the allotments so that expected loads on each of the respective plurality of storage devices do not exceed the upper-limit load values for each of the respective plurality of storage devices and a total of the expected loads is maximized for the categorized data to be processed by a subset of the generated plurality of processing procedures, by considering all subsets of the generated plurality of processing procedures; generate the plurality of subsets by grouping together processing procedures selected from among the generated plurality of processing procedures, wherein the processing procedures included in each respective subset first access common categorized data stored in one of the storage devices and subsequently access other categorized data in an order different from one or more other processing procedures included in a different subset of the plurality of subsets; calculate the allotments, for each subset of the plurality subsets, so that the expected loads on each of the respective plurality of storage devices do not exceed the upper-limit load values for each of the respective plurality of storage devices, and a total of the expected loads is maximized for the categorized data to be processed by the processing procedures included in the subset; and select, for execution, one subset of the plurality of subsets providing a maximum calculated total of the expected loads, wherein the subset executed by execution of the processing execution module is the selected subset of the plurality of subsets providing the maximum calculated total of the expected loads.