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 de­cen­tral­ized ap­proach­es. Cen­tral­ized databases enable employees to col­lec­tive­ly work on documents or tables, without having to create multiple versions of this 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 geared more towards business customers, NAS home systems are offered as easily ad­min­is­tra­ble, af­ford­able solutions. But what is 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 organizes 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 optimized for storing data in 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.

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 cen­tral­ized 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 realized 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 realized with RAID-0.
  • RAID 1: For RAID 1, data from the RAID con­troller is stored onto 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 checksums for the data blocks that are to be written and saves these so-called parities sep­a­rate­ly on a neigh­bor­ing hard drive. For this process, the con­troller functions in such a way that evenly dis­trib­utes data and checksums evenly through­out all storage devices. Following this, if one hard drive crashes, lost in­for­ma­tion can be restored from the available data blocks. Due 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 a NAS data storage options via a backup man­age­ment software. In general, regular data backups occur through a syn­chro­niza­tion 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 dollar 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 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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