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What Is Network-Attached Storage?

What Is Network-Attached Storage

Date First Published: 20th April 2022

Topic: Computer Networking

Subtopic: Network Hardware

Article Type: Computer Terms & Definitions

Difficulty: Medium

Difficulty Level: 6/10

Learn more about what network-attached storage is in this article.

Often abbreviated to NAS, network-attached storage is a single storage device that connects to a LAN. Instead of computers sharing their files separately, all of the shared data is stored on a single NAS server, which provides a simpler and more reliable way of transferring files. NAS servers are much more reliable since they provide one place for sharing files on a network. If a computer is turned off or disconnected from the network, its files will be unavailable to other systems. The aim of NAS was to resolve this issue.

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NAS servers have a large amount of shared storage space, since they usually consist of multiple hard drives.


NAS connects to a network through the use of Ethernet and it can be configured to share files with multiple computers on the network together as well as which computers have access to the server. For example, NAS may allow all computers to access or it may only allow access to a limited number of authenticated computers.

NAS servers do not normally have a keyboard or display and are configured and managed with a browser-based application. Each NAS belongs on the LAN as a node, which is identified by its unique IP address.

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NAS servers are mostly used in business networks. However, they can also be used in home networks, providing a way for a household to share their data with each other and store backups.

Types Of NAS

  • Low-end NAS - This provides low cost, fast and simple file storage with simplified backup. It combines desktop storage together.
  • Midmarket NAS - This provides low cost, shared access to large amounts of files. It combines multiple file servers together.
  • High-end NAS - This provides shared access to large amounts of files and it integrates with a SAN. It is low-cost and integrates a large number of file servers together.

Difference Between NAS and SAN

NAS servers and SANs (Storage Area Networks) are not the same. SANs consist of several data storage devices and a NAS server is a single storage device that connects to a LAN and provides one place for shared storage space.

Also, a SAN provides full block-level access to the disk space of a server. NAS would be viewed as a file system by an operating system and a SAN would appear on the disk as the operating system.

NAS moves traffic over the TCP/IP protocol and SANs route network traffic over the Fibre Channel Protocol. That protocol is specifically designed for storage networks.

Scale-Up NAS, Scale-Out NAS, and Object Storage

Two versions of NAS exist, called scale-up and scale-out. For handling structured data, object storage can be used as an alternative. Note that the NAS head is the hardware that carries out the control functions.

  • Scale-up NAS - The NAS provides access to a backend system through an internet connection. The capacity is extended by a two-controller system with added drive shelves depending on the scalability of the controller.
  • Scale-out NAS - Larger heads and more hard disks are stored for the purpose of increasing storage capacity. Scale-out NAS provides the flexibility to fit the needs of a business.
  • Object storage - A new way for easily scalable storage in web-scale environments. POSIX or other file systems are not used and all objects are presented in a flat address space. Every object is described by bits of metadata, which allows for quick identification with a flat address namespace. It is believed that object storage will overtake scale-out NAS.


The Newcastle Connection by Brian Randell and his colleagues at Newcastle University gave a demonstration of remote file access across a number of UNIX machines in the early 1980s. In 1983, Novell’s NetWare operating system and NCP protocol were introduced. Sun Microsystems’ introduction of NFS allowed network servers to share their storage space with networked clients together after the Newcastle Connection. In addition to this new requirement, the LAN Manager software and protocol were developed by 3Com and Microsoft.


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