Patent ID: 8015157

Claim:
A file-sharing system comprising: a storage device that has one or more volumes; and a file server that manages files stored in the volumes by using one or more file systems created for the volumes, a unified file system which virtually integrates the file systems, and snapshots of at least one of the file systems which are acquired at one or more time points, wherein the storage device and the file server are communicably coupled to each other, and wherein the file server comprises: a memory that stores snapshot management information which includes mount paths of the snapshots, and represents the snapshots acquired at respective time points, and file storage location management information which includes file paths of the files, and represents storage locations of the files when the unified file system manages the files; and a processor that executes a snapshot management information modification control for acquiring a snapshot for a file system having the snapshot when receiving a snapshot acquisition request including a mount path of the snapshot from a computer, and modifying the snapshot management information by using the acquired snapshot, a file rewrite control for copying the file storage location management information at a time point when the snapshot is acquired, and rewriting file paths of files included in the copied file storage location management information by using a mount path of the acquired snapshot, and a file access control for performing a file access to the file managed by the acquired snapshot when receiving a file access request from a computer to the rewritten file which is stored in a volume for which a file system not having a snapshot is created.