Network Attached Storage (NAS) is a computer data storage server, which is attached to a computer network. The file-level server provides data access to a diverse group of clients. It consists of one or many storage drives, which are arranged in redundant storage containers (RAID). It is a specialized computer, which is designed to act as a purpose-built server and helps in sharing files over the network. NAS acts as both, file system and storage system. This feature makes it a better option than SAN (Storage Area Network), which offers just block-based storage.
NAS devices can be broadly divided into three categories – Computer-Based NAS, ASIC based NAS, and Embedded System Based NAS. Along with providing the centralized storage to client computers, NAS also helps lower-cost systems, such as, fault-tolerant and load-balancing emails, and web server systems.
Network Attach Storage is a type of server with a storage capacity which is connected directly to the network and can be located anywhere. It is one of the complete storage system which is designed to be attached to a traditional data network. NAS is less expensive and less complicated to understand it.
NAS is a self-enclosed system containing the ability to connect to the network and manage the disks. It is easily added as needed. Because the data stored on NAS is generally more static, lower priced and slightly slower IDE disk drives can be used. For an end user, they are unlikely to notice the difference in speed between NAS and SAS.
Server Attach Storage (SAS) are units containing one or many disk drives. These attach to a network file server. The server controls access to the disks. Generally, the server has to be taken down in order to add SAS. Seeing as servers work with highly volatile data, the drives used in SAS are expensive, high transfer rate drives. The data stored on a server is often used to feed applications running on that server.
Storage Area Networks (SAN) are generally very large storage networks. Basically, a SAN has its own network for transferring data within the SAN. It may be comprised of many individual storage units. A NAS unit can be part of a SAN. SANs generally have many protocols and structures for managing large amounts of data quickly and reliably. NAS units are generally smaller.
A Network Attached Storage device is a box that allows the storage of large amounts of data outside the personal computer. NAS box does not require the computer to be switched onto access the content as the NAS box is a self-contained computer with its own operating system, with the sole purpose of providing the storage. It is just like an external hard drive but instead of being attached to a single computer, it attaches itself to the personal network so it can be accessed by any devices on it.
NAS server are typically attached to the network via Ethernet. However, NAS devices are also available which connect to Fibre Channel networks.
Wireless 802.11 Network Attached Storage devices are now appearing on the market.