Abstract: Thin-Provisioning serves effectively to improve storage utilization in a storage system by allocating space on demand. Nevertheless, in the environment of Storage Area Network (SAN), it is difficult to reclaim the storage released from applications on thinprovisioning storage devices. The paper presents a method to reclaim free space for most file system on a thin-provisioning storage device. The method includes recognizing the format of the file system, monitoring the modification to the metadata of the file system to determine unused storage and reclaiming the space after a test based on data consistency. The prototype experiments show that the method can indeed reclaim free space for NTFS effectively, and moreover, the impact on the business applications is greatly reduced.

Key words: Thin-Provisioning, reclaiming storage, SAN, file system, metadata