Patent ID: 7222194

Claim:
A backup system comprising: a network attached storage including a primary volume and a secondary volume; and a backup server connected to the network, which accepts inputs of a backup request or a restore request, along with at least one identifier of backup/restore target from an operator, wherein: said network attached storage comprises: resynchronization means for performing a resynchronization process when the backup request is received at a time point that consistency of a file system can be guaranteed, the resynchronization process making the contents of the primary and secondary volumes coincide with each other; data transferring means for splitting the secondary volume from the primary volume and transferring data identified with the backup target identifier of the secondary volume to said backup server; and agent means for communicating with the backup server to receive therefrom a file list request with the identifier of backup/restore target and for controlling the resynchronization means and the data transferring means, the agent means configured to send a file list to the backup server in response to receiving the file list request from the backup server, the file list including identifiers of files stored on the secondary volume and information for each file indicating whether or not said each file has been backed up, wherein the backup server sends backup operation commands to the agent means, based on files identified in the file list, in order to perform a backup operation of the files stored in the secondary volume.