An information system according to one embodiment of this invention includes a first computer which is an SDS (Software Defined Storage) having a virtualization function and a second computer which is an SDS. The first computer can provide a logical volume using a volume in the second computer as a storage region by the virtualization function. When the information system receives a direction to install a storage control program to the second computer, the information system specifies the logical volume using the volume of the second computer as the storage region among logical volumes in the first computer, and then moves data stored in the volume of the second computer used by the specified logical volume as the storage region to a storage device in the first computer. Thereafter, the storage control program is installed in the second computer.