Network-attached storage is a type of dedicated file storage device that provides local area network (LAN) users with centralized, consolidated disk storage through a standard Ethernet connection.
NAS devices are connected to the LAN as an independent network device and assigned an IP address. The primary advantage of NAS devices is that network storage is no longer limited to the storage capacity of a computing device or the number of disks in a local server. Many NAS products can hold enough disks to support RAID, and multiple NAS appliances can be attached to the network for storage expansion.
NAS devices typically do not have a keyboard or display and are configured through a web-based management utility. Some NAS boxes run a standard operating system (OS) like Microsoft Windows, while others may run their own proprietary operating systems. Although Internet Protocol (IP) is the most common network protocol, some NAS products may support other network protocols such as Network File System (NFS), Internetwork Packet Exchange (IPX), NetBIOS Extended User Interface (NetBEUI) or Common Internet File System (CIFS), an enhanced version of the Microsoft open, cross-platform Server Message Block (SMB) protocol. Some NAS products also support Gigabit Ethernet (GigE) for faster data transfers across the network.
NAS products are often categorized as being enterprise, mid-market or desktop. Such categorizations are usually based on the NAS device's number of drives, its drive support, its drive capacity and its scalability.