A network storage server (NAS) is a file-based storage architecture, consisting of one or more servers with dedicated disks where data is stored and shared with many clients connected to a network. NAS is one of the three main storage architectures, along with local storage area networks (SAN) and direct-attached storage (DAS). It is the only one that is both networked (by definition) and fully responsible for all network storage.
If we compare the NAS to storage volumes that are more familiar to you, such as your computer’s hard drive, an external hard drive, a CD or a USB key, we see that a NAS architecture allows you to store and share files in the same way. The difference is elsewhere. Indeed, a hard drive, internal or external, a CD and a USB key can only connect to one device at a time, while the NAS connects several devices at the same time.
NAS units are designed to distribute data in the form of files. Although technically capable of performing general server tasks, NAS units often have a role that is limited to running software that protects data and manages permissions. It is for this reason that they do not need a full operating system. Most NAS units include a lightweight operating system, configured for data storage and presentation.
To present these files, the NAS unit uses standard file protocols, such as NFS (Network File System), SMB (Server Message Block), CIFS (Common Internet File System) or AFP (Apple Filing Protocol), which communicate with Linux, UNIX, Microsoft Windows and Apple devices.
Here are the main advantages of a NAS server:
- Scalability: To increase the storage capacity of a NAS, simply add hard drives to it. No need to upgrade or replace servers, let alone disable the network.
- Performance: Since the NAS is a file system, other devices on the network do not need to be responsible for file sharing. In addition, the NAS is often configured for specific use (storage of Big Data or multimedia content, for example), which allows higher performance.
- Simple configuration: NAS architectures are often accompanied by simple scripts or even provided in the form of preinstalled appliances with a streamlined operating system, which considerably reduces system configuration and management time.
- Accessibility: all networked devices have access to the NAS.
- Fault tolerance: It is possible to format the NAS so that it supports replicated disks, a RAID system or erasure encryption to ensure data integrity.
How does network storage work?
Simply put, NAS is an approach that aims to simplify access to data stored between devices on a network. By installing specialized software on dedicated hardware, businesses can take advantage of single point shared access with security, management, and fault tolerance features. The NAS communicates with other devices using file protocols. It is one of the easiest formats to use, especially when compared to block or object storage systems.
Equipment
The hardware that makes up a NAS is usually called a NAS enclosure, NAS unit, or NAS server. The server itself is essentially made up of storage disks, processors and RAM, like most other servers. It is possible to add more RAM to a NAS unit or to customize the type and capacity of the disks according to specific needs. The main difference between a NAS and a general-purpose storage server is rather at the software level.
Software
A NAS unit includes software deployed on a lean operating system, which is generally integrated into the hardware. As for the general-purpose server, it has a complete operating system and sends and receives hundreds or thousands of small unique requests per second. The operating system of a NAS manages only two tasks: data storage and file sharing.
Protocols
A NAS unit is formatted with data transfer protocols, which are frequently used for sending data between multiple devices. Clients can access these protocols via a network switch, which is a central server that connects all elements of the network and routes requests. In practice, data transfer protocols allow you to access files stored on another computer as if they were your own.
Several protocols can be used on a network, but the two most important are Internet Protocol (IP) and Transmission Control Protocol (TCP). The TCP protocol makes it possible to group data into packets before sending them via the IP protocol. To simplify matters, TCP packets are comparable to ZIP files and the IP protocol to email addresses. If your grandparents are not registered on social networks and they do not have access to your personal cloud, you must send them your vacation photos by email. You can also collect these photos in ZIP files to avoid sending them one by one. Similarly, the TCP protocol gathers files into packets before sending them over a network via IP addresses.
The files transferred via these protocols can be in the following formats:
NFS (Network File System): this protocol is frequently used on Linux and UNIX systems. This independent protocol works on all types of hardware, operating systems and network architectures.
SMB (Server Message Block): most systems that use the SMB protocol are running Microsoft Windows. It is then called “Microsoft Windows Network”. This protocol was developed from the CIFS (Common Internet File System) protocol and it is for this reason that it sometimes appears under the name CIFS / SMB.
AFP (Apple Filing Protocol): this is a proprietary protocol, reserved for Apple devices that run macOS.
Is the NAS, however, a cloud?
No. A NAS is not a cloud. A cloud is a pool of virtual resources (like a storage volume), which are orchestrated by management and automation software and accessible on-demand via self-service portals. These resources are automatically sized and dynamically allocated. To be considered a real cloud, a NAS should be virtualized in the form of resource pools. These would then have to be orchestrated by management and automation software so that we can speak of cloud computing.
In short, the NAS is somewhere between a local storage system and a cloud storage system. The NAS has certain characteristics of local storage (on-site access, wired connections) and certain characteristics of cloud storage (network access, self-service), but it does not include the necessary management and automation software. to evolve quickly and to provide measurement services. If the NAS is not a cloud, it can nevertheless play a fundamental role in cloud computing.
Comparison between a network storage server and other types of storage
SAN networks
A storage area network (SAN) enables what is known as block storage. Block storage separates storage volumes (such as hard drives, virtualized storage nodes, or cloud storage resource pools) to make smaller volumes called blocks, which can be adapted to formats various protocols. For example, it is possible to adopt a block to the format of the NFS protocol, another to the format of the AFP protocol and a third to the format of the SMB protocol. This option provides more flexibility to users but forces them to manually navigate among resources since block storage collects data arbitrarily.
DAS storage
Direct attached storage (DAS) corresponds to a storage system directly connected to a single computer. It is not on a network, so other devices cannot easily access it. DAS is the precursor to the NAS, and each DAS device must be managed separately, while the NAS manages the entire network. The simplest example of DAS is a computer’s hard drive. Before computer B can access the data stored on the hard disk of computer A, you must remove the hard disk from computer A and physically connect it to computer B, or configure a connection between the two computers.
Software storage
A software storage solution is storage management software that operates independently of the underlying hardware. It is thus possible to install a software storage solution on a NAS unit, which makes it possible to adapt the hardware to particular workloads. Once the software storage solution is installed, the storage hardware can be clustered so that several servers can operate as a single system dedicated to a specific function. For example, it is possible to configure a cluster of servers for storing user directories and NFS / CIFS files, then configure another in block mode for storing photos and other multimedia content. Some solutions that combine NAS and software storage can even be consolidated and provide more than one petabyte of data in 30 minutes or less.
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