1. A method of controlling a computer system, which includes a host computer and one or more storage systems coupled to the host computer via a network, wherein the host computer includes a first interface coupled to the network, a first processor coupled to the first interface, and a first memory coupled to the first processor, wherein each of the storage systems includes a port coupled to the network, a second processor coupled to the port, and a second memory coupled to the second processor, wherein at least one of the one or more storage systems includes a physical storage device for storing data written by the host computer, wherein a physical storage area of the physical storage device is allocated to a logical storage area, wherein the first processor executes an application program stored in the first memory to execute an application job which executes data I/O in the logical storage area via the first interface, wherein the second processor executes a management program stored in the second memory to execute a management job which executes the data I/O in the logical storage area for managing the storage systems, the managing job relating to execution of a migration, and wherein the method comprises: determining whether at least one of resources of the computer system used for the data I/O of the application job is also used for the data I/O of the executed management job when performance of the application job drops below a predetermined first threshold value; and displaying information indicating the executed management job when it is determined that at least one of the resources used for the data I/O of the application job is also used for the data I/O of the executed management job, determining whether to limit the execution of the management job when it is determined that at least one of the resources used for the data I/O of the application job is also used for the data I/O of the management job; limiting the execution of the management job according to a result of the determination, wherein the second processor executes data copying processing from a first logical storage area of the logical storage areas of the at least one storage system to a second logical storage area of the logical storage areas as the management job, wherein the data I/O of the management job is data I/O for the data copying processing, wherein the management job is divided into a plurality of copy jobs, which are executed in parallel for execution of the data copying processing, each of the plurality of copy jobs copying a part of the data from the first logical storage area to the second logical storage area, and wherein the step of limiting execution of the management job is performed by reducing the number of copy jobs executed in parallel.