1. A system comprising: a plurality of physical calculation nodes each including a first processor; and a controller including a memory and a second processor coupled to the memory, wherein the second processor is configured to execute a process including: upon receipt of a target job, executing a type determination test on the target job by executing a part of the target job on a given number of first physical calculation nodes selected from among unused physical calculation nodes of the plurality of physical calculation nodes, and monitoring a processing load for execution of the target job, determining a type of the target job, based on the processing load obtained by the type determination test, transmitting a first instruction to the given number of first physical calculation nodes selected from among the unused physical calculation nodes to execute the target job by using the given number of first physical calculation nodes, when the determining determines the type of the target job is a first type, and transmitting a second instruction to a second physical calculation node selected from among the unused physical calculation nodes to execute the target job by using the second physical calculation node, when the determining determines the type of the target job is a second type which requires a lower processing load for the execution than the first type, wherein the second instruction activates the given number of virtual machines to run on the second physical calculation node to execute the target job by using the given number of virtual machines in parallel within the second physical calculation node to decrease a number of physical calculation nodes that are newly selected from among the unused physical calculation nodes for execution of the target job.