Patent ID: 8285749

Claim:
A computer system, comprising: a file access controller; a first storage device storing first file data of a first file; a second storage device storing second file data of a second file, which is moved from the first storage device by the file access controller based on a predetermined moving condition; and at least one client computer sending access requests of the first file and the second file, wherein the file access controller stores configuration information about a virtual directory tree and provides a normal directory tree and the virtual directory tree to the at least one client computer based on the configuration information, wherein the file access controller provides the first file to the at least one client computer through both of the normal directory tree and the virtual directory tree, wherein, based on the configuration information, the file access controller switches providing of the second file to the at least one client computer, depending on a used directory tree, which is used by the at least one client computer, and which is the normal directory tree or the virtual directory tree, wherein, in case of the used directory tree being the normal directory tree, the file access controller provides the second file to the at least one client computer, as the providing of the second file, and wherein, in case of the used directory tree being the virtual directory tree, the file access controller prevents to provide the second file to the at least one client computer, as the providing of the second file.