Network-attached storage facts for kids

A 5-bay NAS server, which is a type of NAS device.

Network-attached storage (NAS) is like a special computer server that connects to a computer network. Its main job is to store files and let many different computers access them. Think of it as your own private cloud storage device at home or in an office. The word "NAS" can mean both the technology itself and the actual device built for this purpose.

What is NAS?

A NAS device is made to be really good at sharing files. It's often a special computer built just for this job. NAS systems have one or more storage drives inside. These drives are often set up in a special way called RAID to keep your data safe and make it faster to access.

NAS devices let you get to your files using common network rules, like NFS, SMB, or AFP. Since the mid-1990s, NAS devices became popular because they make it easy to share files among many computers. They also take the job of file sharing away from other computers on the network. This means a NAS can give you faster access to your data, is easier to manage, and simpler to set up.

Sometimes, NAS devices use special hard disk drives. These drives are similar to regular ones but are designed to work better in NAS systems, especially when using RAID. For example, they might handle vibrations better or recover from errors differently so they don't slow down the whole system.

How NAS Works

A NAS unit is a computer that connects to your network. It only provides file storage services to other devices on that network. Even though it's a computer, it's not meant to be a general-purpose server. For example, most NAS units don't have a keyboard or a screen. You control and set them up over the network, usually using a web browser.

NAS systems often use a very simple operating system because they only need to do one main job: store and share files. They usually have one or more hard drives, often set up in a RAID system for safety and speed.

NAS uses special rules called "protocols" to share files. These include NFS (popular with UNIX systems), SMB (Server Message Block) (used with Microsoft Windows computers), and AFP (used with Apple Macintosh computers). Most NAS units can work with several of these protocols.

NAS vs. DAS

Let's compare NAS with something called direct-attached storage (DAS). The main difference is how they connect. DAS is just extra storage connected directly to one computer, usually with a USB or Thunderbolt cable. It's not necessarily connected to a network. NAS, on the other hand, is built specifically to share files easily over a network.

Both DAS and NAS can use RAID to make sure your data is always available, even if one drive fails.

When you compare how fast they are, NAS speed depends a lot on your network's speed and how busy it is. DAS speed depends on the cable connection to the computer. NAS devices might not be as easy to change or upgrade their parts (like the CPU or memory) as a regular computer. However, many NAS solutions let you install apps to add more features, like video surveillance or media streaming. DAS usually just focuses on storing data.

NAS vs. SAN

This image shows how NAS and SAN work differently in a network.

NAS gives you both storage space and a way to organize your files (a file system). This is different from a storage area network (SAN). A SAN only gives you raw storage space, like a blank hard drive. It's up to the computer using the SAN to create its own file system. SANs use different rules like Fibre Channel or iSCSI.

Think of it this way: A NAS looks like a file server to your computer. You can connect to it and see shared folders, just like connecting to another computer's shared drive. But a disk from a SAN looks like a brand new, empty hard drive to your computer. You have to format it and set it up before you can use it.

Even though they are different, NAS and SAN can work together. Some systems can offer both file-level (NAS) and block-level (SAN) storage from the same device.

History of NAS

The idea of sharing files over a network started a long time ago. In the early 1980s, a project called the "Newcastle Connection" showed how UNIX computers could access files from each other. Soon after, companies like Novell and Sun Microsystems (with their NFS) created ways for servers to share their storage space with other computers on a network. 3Com and Microsoft also developed software like LAN Manager for this new market.

3Com made one of the first special servers just for sharing files. Then, a company called Auspex Systems made dedicated NFS servers for UNIX users. Some engineers from Auspex later started NetApp, which made NAS devices that could work with both Windows and UNIX systems. This helped create the market for special NAS devices we see today, with companies like NetApp and EMC leading the way.

In the early 2000s, new companies started making "clustered NAS." These systems could spread data across many servers, making them even bigger and faster. Companies like Isilon and Gluster were part of this trend.

Around 2009, some NAS companies started adding online backup features to their devices. This made it easier to protect your data by sending copies to the internet.

By 2021, there were three main types of NAS solutions:

• Consumer NAS: These are cheaper options for homes, usually with 1 to 5 hard drives.
• Small-to-medium business (SMB) NAS: These are for smaller companies, with 2 to 24 or more hard drives. They come in different sizes and have more features.
• Enterprise NAS: These are for very large businesses and have the most advanced software and features.

Most NAS devices are sold without hard drives. This lets you choose the size, cost, and quality of the drives you want to use.

How NAS Devices Are Made

Manufacturers build NAS devices in a few different ways:

• Computer-based NAS: These use regular computer parts, like Intel or AMD processors. They run software to share files (like FTP or SMB). These NAS types use the most power but are also the most powerful. Companies like Synology and QNAP make these.
• Embedded-system-based NAS: These use smaller, more energy-efficient processors (like ARM or MIPS) and a simpler operating system. They use less power and are good for most home or small office needs.
• ASIC-based NAS: These use a single special chip (an ASIC) that handles all the file sharing. They use very little power because most of the work is done by hardware. However, they usually only support basic file sharing like SMB and FTP.

Uses of NAS

NAS is great for more than just storing files for computers. It can also help make other systems simpler and cheaper. For example, it can provide storage for email and web servers, helping them work better and stay online.

A big new market for NAS is in homes, where people have lots of digital photos, videos, and music. You can now buy affordable NAS devices for home use that are much smaller than the ones for businesses. They often cost only a little more than a regular external hard drive that connects directly to your computer. Many of these home devices use small, efficient processors and a simple Linux operating system.

Examples of NAS

Open-source NAS Software

There are free, open-source programs based on Linux and FreeBSD that can turn a regular computer into a NAS. These are designed to be easy to set up, often using a web browser.

You can run them from a virtual machine, a Live CD, or a bootable USB drive. They use free software like Samba (for Windows file sharing), NFS (for UNIX/Linux file sharing), and FTP to share files.

Network Protocols for NAS

Clustered NAS

A clustered NAS is a type of NAS that uses a special file system running on many servers at the same time. The main difference is that a clustered NAS can spread data and information about files across all the servers or storage devices in the cluster. Just like a regular NAS, a clustered NAS still lets you access your files from any of the servers, no matter where the data is actually stored.

Images for kids

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  A 5-bay NAS server

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  Visual differentiation of NAS and SAN use in network architecture

See also

In Spanish: Almacenamiento conectado en red para niños