Method of switching distributed storage modes in GNS

A computer system, comprising:

• one first server which is accessed by a client computer;
• a plurality of second servers which are coupled to the first server via a network;
• and
• a plurality of storage subsystems which are coupled to the second servers,
• wherein at least one of the first server and the second servers applies to each file stored in the storage subsystems one of a first file storage mode in which one file is stored in one of the storage subsystems and a second file storage mode in which one file is stored in two or more of the storage subsystems in a distributive manner,
• wherein the first server integrates directory structures that are unique throughout the respective second servers to provide the integrated directory structures as a directory structure that is unique throughout the computer system to the client computer, and
• wherein at least one of the first server and the second servers analyzes a utilization state of the file and switches a file storage mode that is currently applied to the file to the other file storage mode based on a change in the analyzed file utilization state.