View source for Network Attached Storage

[[Image:San-vs-nas.jpeg|thumb|Perbandingan secara visual NAS vs. [[Storage area network|SAN]] di arsitektur jaringan]]

'''Network-attached storage''' ('''NAS''') adalah file level [[computer data storage]] yang tersambung [[computer network]] providing data access to [[Heterogeneous computing|heterogeneous]] clients.

==Description ==

A NAS unit is a computer connected to a network that only provides file-based data storage services to other devices on the network. Although it may technically be possible to run other software on a NAS unit, it is not designed to be a general purpose server. For example, NAS units usually do not have a keyboard or display, and are controlled and configured over the network, often using a browser.

A fully-featured operating system is not needed on a NAS device, so often a stripped-down operating system is used. For example, [[FreeNAS]], an [[open source]] NAS solution designed for commodity PC hardware, is implemented as a stripped-down version of [[FreeBSD]]. 

NAS systems contain one or more hard disks, often arranged into logical, redundant storage containers or [[RAID]] arrays (redundant arrays of inexpensive/independent disks). NAS removes the responsibility of file serving from other servers on the network.
  
NAS uses file-based protocols such as [[Network File System (protocol)|NFS]] (popular on [[UNIX]] systems), SMB/CIFS ([[CIFS|Server Message Block/Common Internet File System]]) (used with MS Windows systems), or [[Apple Filing Protocol|AFP]] (used with [[Macintosh|Apple Macintosh]] computers). NAS units rarely limit clients to a single protocol. 

===NAS vs SAN===

NAS provides both storage and a [[file system]]. This is often contrasted with SAN ([[Storage Area Network]]), which provides only block-based storage and leaves file system concerns on the "client" side. SAN protocols are [[SCSI]], [[Fibre Channel]], [[iSCSI]], [[ATA over Ethernet]] (AoE), or [[HyperSCSI]].

Despite their differences, SAN and NAS are not mutually exclusive, and may be combined as a [[Storage area network#SAN-NAS hybrid|SAN-NAS hybrid]], offering both file-level protocols (NAS) and block-level protocols (SAN) from the same system. An example of this is [[Openfiler]], a free software product running on Linux.

==History==
In the early 1980s, the 'Newcastle Connection' by [[Brian Randell]] and his colleagues at [[Newcastle University]] demonstrated and developed remote file access across a set of UNIX machines.[[Novell]]'s [[NetWare]] server operating system and [[NetWare Core Protocol|NCP]] protocol was released in 1983. Following the Newcastle Connection, [[Sun Microsystems]]' 1984 release of [[Network File System (protocol)|NFS]] allowed network servers to share their storage space with networked clients.  3Com and [[Microsoft]] would develop the [[LAN Manager]] software and protocol to further this new market.  [[3Com]]'s [[3Server]] and [[3+Share]] software was the first purpose-built server (including proprietary hardware, software, and multiple disks) for open systems servers.  Inspired by the success of [[file server]]s from Novell, [[IBM]], and Sun, several firms developed dedicated file servers.  While 3Com was among the first firms to build a dedicated NAS for desktop operating systems, [[Auspex Systems]] was one of the first to develop a dedicated NFS server for use in the UNIX market.  A group of Auspex engineers split away in the early 1990s to create the integrated [[NetApp filer]], which supported both Windows' CIFS and UNIX'es NFS, and had superior [[scalability]] and ease of deployment. This started the market for [[Proprietary hardware|proprietary]] NAS devices now led by NetApp and EMC Celerra.

Starting in the early 2000s, a series of startups emerged offering alternative solutions to single filer solutions in the form of clustered NAS &ndash; Spinnaker Networks (acquired by [[NetApp]] in February 2004), [[Exanet]] (acquired by [[Dell]] in February 2010), [[ONStor]] (acquired by LSI in 2009), [[IBRIX]] (acquired by HP), [[Isilon]], [[PolyServe]] (acquired by HP in 2007), and [[Panasas]], to name a few.

In [[2009]], NAS vendors (notably [[CTERA Networks]] and [[NETGEAR]]) began to introduce [[Online Backup]] solutions integrated in their NAS appliances, for online disaster recovery.

==Benefits==
The key difference between [[direct attached storage]] (DAS) and NAS is that DAS is simply an extension to an existing server and is not networked while NAS sits on a network as its own entity; it is easier to share files with NAS.

Availability of data might potentially be increased with NAS if it provides built-in [[RAID]] and [[Cluster (computing)|clustering]] capabilities.

Performance can be increased by NAS because the file serving is done by the NAS and not done by a server responsible for also doing other processing. The performance of NAS devices, though, depends heavily on the speed of and traffic on the network and on the amount of cache memory on the NAS computers or devices.

==Drawbacks==
Because of the need to support multiple protocols and the shared OS layer running on shared hardware, the NAS has its limitations compared to the [[Direct Attached Storage|DAS]]/[[Storage area network|SAN]] systems.
If the NAS is occupied with too many users, too many I/O operations, or CPU processing power that is too demanding, the NAS reaches its limitations. A server system is easily upgraded by adding one or more servers into a cluster, so CPU power can be upgraded, while the NAS is limited to its own hardware, which is in most cases not upgradeable.

Certain NAS devices fail to expose well-known services that are typical of a file server, or enable them in a way that is not efficient. Examples are: ability to compute disk usage of separate directories, ability to index files rapidly (locate), ability to mirror efficiently with [[rsync]]. One may still use rsync, but through an NFS or CIFS client; that method fails to enumerate huge file hierarchies at the nominal speed of local drives and induces considerable network traffic. 

NAS is effectively a server in itself, with all major components of a typical PC – a CPU, motherboard, RAM, etc. – and its reliability is a function of how well it is designed internally.  A NAS without redundant data access paths, redundant controllers, redundant power supplies, is probably less reliable than [[Direct Attached Storage]] (DAS) connected to a server which does have redundancy for its major components.

==Uses==
NAS is useful for more than just general centralized storage provided to client computers in environments with large amounts of data. NAS can enable simpler and lower cost systems such as load-balancing and fault-tolerant email and web server systems by providing storage services. The potential emerging market for NAS is the consumer market where there is a large amount of multi-media data. Such consumer market appliances are now commonly available.  Unlike their [[rackmount]]ed counterparts, they are generally packaged in smaller form factors. The price of NAS appliances has plummeted in recent years, offering flexible network-based storage to the home consumer market for little more than the cost of a regular [[Universal Serial Bus|USB]] or [[FireWire]] external hard disk. Many of these home consumer devices are built around [[ARM architecture|ARM]], [[PowerPC]] or [[MIPS architecture|MIPS]] processors running an [[embedded Linux]] [[operating system]].

==Open source implementations==

[[Open source]] NAS-oriented distributions of [[Linux]] and [[FreeBSD]] are available, including [[FreeNAS]], [[Gluster]], [[Openfiler]] and the Ubuntu-based [[TurnKey Linux Virtual Appliance Library|TurnKey]] File Server. [http://www.turnkeylinux.org/fileserver Ubuntu-based TurnKey File Server] These are designed to be easy to setup on commodity PC hardware, and are typically configured using a web browser.

They can run from a [[virtual machine]], [[Live CD]], [[bootable]] USB flash drive ([[Live USB]]), or from one of the mounted hard drives.  They run [[Samba (software)|Samba]] (an [[Server Message Block|SMB]] daemon), [[Network File System (protocol)|NFS]] daemon, and [[FTP]] daemons which are freely available for those operating systems.

[[NexentaStor]], built on the [[Nexenta]] Core Platform, is similar in that it is built on open source foundations; however, NexentaStor requires more memory than consumer oriented open source NAS solutions and also contains most of the features of enterprise class NAS solutions, such as snapshots, management utilities, tiering services, mirroring, and end to end check summing due, in part, to the use of [[ZFS]].

== Clustered NAS ==
A '''clustered NAS''' is a NAS that is using a distributed file system running simultaneously on multiple servers.  The key difference between a clustered and traditional NAS is the ability to distribute (e.g. stripe) data and [[metadata]] across the cluster nodes or storage devices. Clustered NAS, like a traditional one, still provides unified access to the files from any of the cluster nodes, unrelated to the actual location of the data. The examples of commercial products are  [[GlusterFS]] and [[IBM]] [[Scale-out File Services]].

==See also==
*[[List of NAS manufacturers]]
*[[File Area Networking]]
*[[Storage area network]]
*[[Shared disk file system]]
*[[Disk enclosure]]
*[[Network architecture]]
*[[Network protocols]] used to serve NAS:
**[[CIFS]]
**[[Network File System (protocol)|NFS]]
**[[FTP]]
**[[SSH file transfer protocol|SFTP]]
**[[HTTP]]
**[[UPnP]]
**[[Apple Filing Protocol]] (AFP)
**[[rsync]]
**[[Andrew file system]] (AFS)
*[[Network File Control]]

==External links==
* [http://www.nas-central.org NAS-Central] - A community site detailing information on many NAS devices and associated articles


==Pranala Menarik==

* [[Western Digital MyBook World Edition]]
* [[NAS: Buffalo LinkStation Mini]]
* [[NAS: Buffalo LinkStation Mini - menu konfigurasi utama]]
* [[NAS: Buffalo LinkStation Mini - setup network]]
* [[NAS: Buffalo LinkStation Mini - setup system]]
* [[NAS: Buffalo TeraStation]]
* [[Network Attached Storage]] ([[NAS]]).
* [[Membuat Repository Ubuntu Lokal menggunakan NAS]]