The technique of the present invention enhances reading speed of data from a disk device in a computer system capable of transmission and reception of the data via a node device 200 between a client 100 and a storage device 300. A share volume PDc and specific volumes PDa and PDb are defined in the disk device on the storage device 300. Common data among respective clients and specific data corresponding to the individual client are stored in the share volume and specified volumes, respectively. Once respective clients request virtual volumes VDa and VDb to read the data, the storage device reads out the corresponding data from the share volume or the specific volume. This application avoids lowering the reading speed regardless of the concentration of accesses from a plurality of clients because most data can be read from the share volume.