Centrally ac­cess­ible data is the backbone of any computer-supported group project. Many companies provide their employees with locally connected computer networks (Local Area Network, LAN) that feature shared storage platforms. Storing data this way offers many ad­vant­ages when compared with de­cent­ral­ised ap­proaches. Cent­ral­ised databases enable employees to col­lect­ively work on documents or tables, without having to create multiple versions of the same document. What’s more, ad­min­is­ter­ing data backups within a shared storage platform proves to be less strenuous than when compared to a range of in­di­vidu­al hard drives. Depending on a company’s size, the technical basis for centrally storing files is composed of file servers, storage networks (storage area networks, SAN), or so-called NAS systems (Network Attached Storage). The latter mentioned option has become in­creas­ingly popular among private users over the last few years. The increased flex­ib­il­ity to centrally manage and access content, like photos, videos, or private music col­lec­tions, through various devices is the main reason behind their pop­ular­ity. In contrast to file servers and SAN solutions, which are primarily more geared towards business customers, NAS home systems are offered as easily ad­min­is­trable, af­ford­able solutions. But what is a NAS server? And to whom are these storage concepts best suited?

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What is a NAS?

Network area storage refers to a dedicated storage device that’s stored in a local network and, com­par­at­ively speaking, more af­ford­able and easier to ad­min­is­ter.

NAS systems are sold by man­u­fac­tures with the guarantee of being complete devices, ready for immediate use. By defin­i­tion, this also means, of course, that all of the necessary hardware and software com­pon­ents are also available. Some popular providers include names like: Synology, Seagate Tech­no­logy, Netgear, QNAP, Buffalo, or Western Digital.

At its core, a NAS is nothing more than a normal computer. Un­der­neath its exterior, you’ll find a CPU, RAM, and a mother board. What’s more, the network storage also has in­ter­faces, like LAN, USB, and WLAN. The central hardware com­pon­ents for the NAS’ storage function are comprised of a certain number of mass storage media, like hard drives and SSD (Solid State Drives) and a RAID con­trol­ler (Redundant Array of In­de­pend­ent Disks), which organises these multiple physical com­pon­ents into a virtual drive. In terms of the software, an operating system (generally, this is Linux) and the NAS software are used.

How a NAS system works

NAS systems are es­sen­tially file servers that have been optimised for storing data on local networks. Access to LAN is carried out via the Windows network protocol SMB (Server Message Blocks). NFS (Network File System) or FTP (File Transfer System) are used as the system’s transfer protocols. Apple hardware relies on AFP (Apple Filing Protocol). Ad­di­tion­ally, many NAS systems can also be used to help store Time Machine backups. One of the central functions of network attached storage is the control it offers users when it comes to accessing saved data. This feature is par­tic­u­larly useful for pro­fes­sion­al ap­plic­a­tions; files from different users can be separated from one another while still being saved on the same storage platform. Working in groups is made possible with the support of the proper clearance.

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With its com­par­at­ively low cost, network attached storage also appeals to the SOHO (Small Office, Home Office) market. Ad­di­tion­ally, compared to other al­tern­at­ives, the system requires re­l­at­ively little ad­min­is­trat­ive work, features high security against break­downs, and maintains a good energy balance.

Ad­min­is­tra­tion

Unlike con­ven­tion­al file servers, operating a NAS system requires com­par­at­ively little IT expertise. All network storage settings are managed through a graphical con­fig­ur­a­tion interface, which can be called up in a client’s browser. For easier access to network storage, NAS systems can also in­cor­por­ated into devices, like PCs and laptops, as hard drives; special programs for data transfer aren’t needed. Smart­phones, network-com­pat­ible stereo systems, and smart TVs that don’t allow simple file sharing are able to access photos or videos through streaming servers, such as Twonky­Media, which are in­teg­rated in the software. This enables NAS to be used at home as a cent­ral­ised media storage device.

Pro­tec­tion against system break­downs

One of the deciding cost factors when pur­chas­ing a network storage system is the number of storage media it includes. While entry-level devices with one or two hard drives are aimed at serving private users, options for business-oriented solutions generally contain up to 12 storage slots. These pro­fes­sion­al devices enable complex storage set-ups to be realised that enable greater re­li­ab­il­ity and larger data through­put. In order to achieve these traits, man­u­fac­tur­ers have looked towards so-called RAID systems. Here, data is re­dund­antly dis­trib­uted through­out multiple physical storage media, ensuring the NAS system’s re­li­ab­il­ity and avail­ab­il­ity, even when in­di­vidu­al hard drives crash. When dealing with Network Attached Storage, typical RAID levels are: RAID-0, RAID-1, RAID-5, and RAID-10.

  • RAID 0: strictly speaking, this storage concept isn’t a RAID system; instead, it’s only an ‘Array of In­de­pend­ent Disks’. These can be con­figured in such a way that allows the storage process to be sim­ul­tan­eously allocated to multiple hard drives. This increases the system’s through­put. Data re­dund­ancy cannot be realised with RAID-0.
  • RAID 1: For RAID 1, data from the RAID con­trol­ler is stored on two separate storage devices. This sort of re­dund­ancy requires at least two storage devices. With this storage concept, users only have access to half of the actual storage capacity. However, saved data is still kept when one of the two hard drives crashes.
  • RAID 5: For NAS systems with at least three available hard drives, storing data is done according to RAID-5. This set-up connects redundant data storage with increased through­put by sim­ul­tan­eously operating multiple hard drives. For this storage concept, the con­trol­ler creates check sums for the data blocks that are to be written and saves these so-called parities sep­ar­ately on a neigh­bour­ing hard drive. For this process, the con­trol­ler functions in such a way that evenly dis­trib­utes data and check sums through­out all storage devices. Following this, if one hard drive crashes, lost in­form­a­tion can be restored from the available data blocks. Due to its low costs and high re­li­ab­il­ity, RAID 5 is an es­pe­cially popular storage option.
  • RAID 01 and RAID 10: these storage concepts involve com­bin­a­tions of different RAID levels and can be used with any setup that employs at least four hard drives. A RAID 01 system dis­trib­utes data the same way a RAID 0 system does, i.e. through­out at least two hard drives. This data is then mirrored onto the same number of hard drives according to the RAID 1 scheme. RAID 10, on the other hand, first mirrors the data and then dis­trib­utes it af­ter­wards. In terms of data security, RAID 10 presents the better option given that it’s less prone to crashes and also allows data to be more quickly restored. Both RAID systems only provide users with half of hard drives’ storage ca­pa­cit­ies.

Users who opt out of a RAID level for their NAS are employing what’s known as a JBOD (‘just a bunch of disks’). In this case, the entire storage capacity of all hard drives is available; however, neither the re­li­ab­il­ity nor the through­put speed of the system is improved.

Those who make use of redundant storage strategies should also ensure that they have planned for regular backups. A standard interface for this is the NDMP (Network Data Man­age­ment Protocol). This makes it possible to control NAS data storage options via backup man­age­ment software. In general, regular data backups occur through a syn­chron­isa­tion with a second NAS system and either a USB hard drive or the cloud.

Costs and energy use

There are many options available on the market for NAS systems, including hard drives and cases. For the latter, users can decide them­selves how much storage capacity they need. Free slots make it possible to ret­ro­act­ively expand a network’s storage capacity. While there are entry-level devices available for under £100, high-per­form­ance business models, including storage devices, can easily reach the multi-thousand pound price range. When used within a business context, however, these in­vest­ments often end up paying for them­selves.

Unlike con­ven­tion­al servers, modern NAS systems use far less power; this is due to the models' reduced storage functions. Many devices support highly developed energy saving strategies. Switching a network into standby mode, even for non-stop op­er­a­tions, helps ensure for a more limited energy con­sump­tion, as this function puts devices into a state of hi­berna­tion that have been idling for an extended period of time. And thanks to the Wake-on-LAN (WoL) function, even a de­ac­tiv­ated NAS system can be started again via the network.

Ex­pand­ab­il­ity

 

Generally, it’s not possible to install ad­di­tion­al software with a NAS system — many devices, however, offer ad­di­tion­al functions, such as launching the device as a print server. Some NAS systems also enable online remote access and can be operated as web, FTP, or email servers.

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