Directory-Aware File System Backup to Object Storage for Fast On-Demand Restore

With emerging “pay-as-you-go object storage” services, file system backup to object storage is an attractive option in terms of total cost of ownership. However, if a failure or a disaster occurs, a conventional backup system with object storage requires a long time to recover the necessary data since it must restore the entire directory structure of the file system from object storage before accessing the data. In this paper, 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.