Abstract: A file server is coupled to a plurality of user terminals and a remote file server. The file server, stores, in a storage device, data of files received from the plurality of user terminals, replicates the files to the remote file server, stubs the files stored in storage, and, upon receiving an access request from the user terminal, reads out data of the file from storage and transmits the data to the user terminal if a file related to the access request is not stubbed. If a file related to the access request is stubbed, the file server recalls data of the file from the remote file server and transmits data of the file to the user terminal. The file server replicates, to the remote file server, data of a user who performs a session disconnection request to the file server within a certain time in preference to another user.

Abstract: A file server is coupled to a plurality of user terminals and a remote file server. The file server, stores, in a storage device, data of files received from the plurality of user terminals, replicates the files to the remote file server, stubs the files stored in the storage device, and, upon receiving an access request from the user terminal, reads out data of the file from the storage device and transmits the data to the user terminal if a file related to the access request is not stubbed, and, recall data of the file from the remote file server and transmits data of the file to the user terminal if a file related to the access request is stubbed. The file server replicates, to the remote file server, data of a user who performs a session disconnection request to the file server within a certain time in preference to another user.

Abstract: A computer system and reclamation control method capable of effectively utilizing storage resources of a storage system even under the circumstance where the storage system is operated according to thin provisioning and a file server can obtain snapshots. The present invention is designed so that if a block, to which a host does not refer, but reference from a snapshot remains, exists in a virtual volume of an operation volume, temporary data is written to this block; and as triggered by this writing, data before writing is saved to a difference volume, so that the reference from the snapshot to this block is released and then this block can be reclaimed.

Abstract: A computer system and reclamation control method capable of effectively utilizing storage resources of a storage system even under the circumstance where the storage system is operated according to thin provisioning and a file server can obtain snapshots. The present invention is designed so that if a block, to which a host does not refer, but reference from a snapshot remains, exists in a virtual volume of an operation volume, temporary data is written to this block; and as triggered by this writing, data before writing is saved to a difference volume, so that the reference from the snapshot to this block is released and then this block can be reclaimed.