Patent ID: 7373393

Claim:
A computer system comprising: a first computer that receives access requests to files from at least one client computer; a first storage device system that is connected to the first computer and stores file management information; a second computer that receives access requests to files containing file data from the first computer; a second storage device system that is connected to the second computer and stores the files containing file data; a third computer that manages a history of accesses to the files by the at least one client computer and charges fees to users of the at least one client computer for accessing the files based on the history of accesses to the files; and a network that connects to the at least one client computer, the first computer, the second computer and the third computer, wherein upon receiving file data from the at least one client computer, the first computer assigns first identification information to the file data, and stores the file data in the second storage device system through the second computer, wherein the first storage device system stores the first identification information assigned to the file data by the first computer, and a file name of a file having the file data designated by the at least one client computer as said file management information, wherein upon receiving, from the at least one client computer, a write request requesting write access to a file, which is the target of the write request, the first computer searches an open file table, which registers in corresponding relation file names used by the at least one client computer to designate files, first identification information of files that are open, credential information of users of the at least one client computer who can access the files that are open and information that identifies session information which is generated when a session has been established between the at least one client computer and said first computer, to obtain first identification information of the file, causes a determination whether an user of the at least one client computer has authority to execute the write request based on said credential information and said session information, and if the user of the at least one client computer has authority to execute the write request, assigns to write data received from the at least one client computer with the write request second identification information different from the first identification information assigned to the file data of the file stored in the second storage device system, wherein the first computer stores the write data, through the second computer, in a storage region within the second storage device system that is different from a storage region that stores the file data already stored in the second storage device system, and wherein the first computer correlates the second identification information to a filename of the file and to the first identification information and stores the second identification information in the first storage device system.