In this paper, we propose a new block based storage system. In the proposed storage system, a remote volume is virtualized to the users' information devices as local hard disks or a memory cards. With devices supporting U-Storage, users can read and write their data anytime and anywhere without downloading and uploading operation. Also, the proposed storage system allows multiple clients to access the same volume. It employs a session based locking approach to guarantees file consistency while multiple clients read and write the same volume concurrently.