The present invention provides a data file system with the processing speed being improved, a data access node, a brain node, a data access program storage medium and a brain program storage medium. A brain node receives a data access request a from a NAS client computer, refers to an association table in a hard disk to identify a data access node among data access nodes, and transmits a data access request to the data access node. The data access node accesses data designated by the data access request stored in a hard disk which the node is responsible for accessing and transmits the access result to the requesting NAS client computer.