|Network attached storage (NAS)|
|Sunday, 19 November 2006|
A network attached storage (NAS) device is a self-contained, intelligent storage appliance that attaches directly to a local area network (LAN) and transfers data typically over network standard protocols such as transmission control protocol/internet protocol (TCP/IP) or internet packet exchange (IPX), and using industry standard file sharing protocols such as server message block (SMB), common internet file system (CIFS), network file system (NFS), network control protocol (NCP), apple file protocol AFP, or hypertext transfer protocol (HTTP). The network attached storage is arranged to connect a plurality of storage device systems with the information processing apparatus through the network configured according to the TCP/IP so that the access to the storage device system may be realized on the file basis. Each NAS device is associated with a unique Internet Protocol (IP) address on the network. IP provides the basic communication protocol for a wide variety of computer networks including the Internet. A NAS device typically consists of an engine, which implements the file access services, and one or more storage devices, on which data is stored. A computer host system that accesses NAS devices uses a file system device driver to access the stored data. The file system device driver typically uses file access protocols such as NFS or CIFS. The NAS device having a file-system function is connected with the storage device system, so that the information processing apparatus may access to the storage device system on the file basis. NAS devices interpret these commands and perform the internal file and device input/output (I/O) operations necessary to execute them. In the network attached storage system, a dedicated server that provides file service via a network is provided on a disk array such that storage apparatuses can be directly accessed from the network. The file level access from the information processing apparatuses is allowed because the storage system is coupled to an apparatus having a file system function. The NAS system is equally accessible from any computing device on the network thereby greatly increasing the ability to scale and optimize the storage needs of the network. NAS devices allow the decomposition of server networks to storage-only components and diskless server components. This decomposition offers tremendous advantages to system administrators, including ease of deployment, system management, and enhanced scalability and reliability.
A typical NAS system involves several client computers and a dedicated file server attached via a local area network (LAN). NAS couples a plurality of storage systems managed in a RAID (redundant arrays of inexpensive disks) and information processing apparatuses through a network using TCP/IP to implement file level access to the storage systems. RAID is a method of creating one or more pools of data storage space from several hard drives. RAID combines multiple hard drives in a system, thus ensuring availability of data even if one or more hard drives fail. The function of a NAS system is to increase the overall performance of the system while reducing the total cost of ownership (TCO). The deployment of the NAS equipment provides advantages of the capability of centralized management of data, shared storage among a number of client computers, separate storage from an application server, and higher reliability and higher accessing speeds than hard disks that are employed by personal computers. The NAS system is independent of an operating system of the client computers, enabling the file server to be shared by heterogeneous client computers and application servers. This approach is also scalable and accessible, enabling additional storage to be easily added without disrupting the rest of the network or application servers. Network-attached storage (NAS) provides a solution to improve scalability of existing distributed file systems by removing the server as a bottleneck in using the network as bandwidth to allow parallelism by using striping and more efficient data pass. Network-attached storage offers convenient placement of storage devices. New functionality, such as the appearance of infinite disk capacity and plug-and-play configuration, can be incorporated. Improved performance and functionality at a reduced TCO are made possible by the ever increasing disk and switch device capabilities. An NAS system typically has a backup system for data recorded in a storage apparatus to periodically copy and preserve the data so that lost data can be recovered in the event there is a breakdown of an apparatus, and defect in a software, or when data is lost through erroneous operation.