A special feature of the Online file sharing and storage (pay $5/user/month) ,for example, file locking prevents this problem by enforcing the serialization of update processes to any given file. Most operating systems support the concept of record locking, which means that individual records within any given file may be locked, thereby increasing the number of concurrent update processes. Auto-Expiration can automatically expire. On the other hand a free Online file sharing and storage can get 10GB secure storage with 250MB file upload size but there is no file locking and auto-expiration.