WORM-Based Data Protection Approach

In this paper we present a WORM-based data protection mechanism in the WOWSnap file system. In the WOWSnap, once the WORM files have been created, only the privileged read requests to them are allowed to access, to protect the WORM files against any intentional or accidental deletion or modification. Different from the past works, the WOWSnap provides a capability of efficiently managing the WORM files that have a limited protection period. Once their protection period is expired, to save the costly WORM disk section, the WOWSnap automatically moves those files to the general disk section without any user interference. Also, the WOWSnap provides a snapshot scheme to protect files, including WORMs, against data crash. In the snapshot of WOWSnap, we attempted to minimize I/O processing overhead, by pre-allocating inode and data blocks for the following snapshot image. Also, by using the snapshot spatial algorithm implemented in the WOWSnap, we tried to maintain the disk space allocated for snapshot images as small as possible. A series of measurements were conducted to verify our scheme.