File System Backup to Object Storage for On-Demand Restore

A new backup method, which achieves on-demand restore as part of file system backup to object storage, is proposed. On-demand restore is a function that restores only a certain directory or file according to the request from an end user. The proposed method backs up relationships between a file and an object on a directory basis in order to efficiently handle the relationships in the restore. It is experimentally shown that the proposed method reduces the response time of file access involving restore by over an order of magnitude.