Patent ID: 7899985

Claim:
A file storage method for a computer system having one first file server which is accessed by a client computer, a plurality of second file servers which are coupled to the first file server via a network, and a plurality of storage subsystems which are coupled to the second file servers, comprising: applying to a first file, whose file size is less than a first threshold, stored in the storage subsystems a first file storage mode in which the first file is stored in one of the storage subsystems; applying to a second file, whose file size is more the first threshold, stored in the storage subsystems, one of a second file storage mode in which the second file is stored in two or more of the storage subsystems that are coupled to different second file servers in a distributive manner, and a third file storage mode in which the second file is stored in two or more of the storage subsystems which are coupled to one of the second file servers in a distributive manner; integrating, by the first server, directory structures that are unique throughout the respective second file servers to provide the integrated directory structures as a directory structure that is unique throughout the computer system to the client computer; analyzing, by at least one of the first file server and the second servers, a write frequency of the first file and the second file; switching a file storage mode that is currently applied to the second file to the second file storage mode in a case that the analyzed write frequency of the second file is more than a second threshold; and switching the file storage mode that is currently applied to the second file to the third file storage mode in a case that the analyzed write frequency of the second file is less than the second threshold.