Network-attached storage (NAS) is file-level computer data storage connected to a computer network providing data access to heterogeneous network clients. A NAS unit is essentially a self-contained computer connected to a network, with the sole purpose of supplying file-based data storage services to other devices on the network. The operating system and other software on the NAS unit provide the functionality of data storage, file systems, and access to files, and the management of these functionalities.