What is network-attached storage?

Network-attached storage (NAS) is a file-dedicated storage device that makes data continuously available for employees to collaborate effectively over a network. Any computer network has interconnected server machines and client machines that send requests to the servers. NAS devices are specialized servers that handle only data storage and file-sharing requests. They provide fast, secure, and reliable storage services to private networks.

Why are NAS devices important?

Enterprise and small businesses in many industries choose NAS solutions because they offer effective, scalable, and low-cost storage. Compared to other servers, NAS file servers give faster data access and are easier to configure and manage. They can support various business applications, including private email systems, accounting databases, payroll, video recording and editing, data logging, and business analytics.

Some benefits of NAS include:

Private cloud deployment for organizations

A private cloud is a cloud that hosts resources from an organization’s own data center. It can be based on internal hardware resources or separate infrastructure provided by a third party. You can use NAS appliances to deploy private cloud storage in your organization.

Flexible local storage solutions for small businesses

NAS systems can be customized based on the size and requirements of the organization. Both low-cost, less storage, and more expensive high-end devices are available in the market.

What is network-attached storage used for?

Organizations use NAS solutions to perform a number of tasks including:

  • File storage and sharing
  • Create active data archives or for data backup and disaster recovery
  • Host virtual desktop infrastructure.
  • Test and develop web-based and server-side web applications
  • Stream media files and torrents
  • Store images and videos that require frequent access
  • Create an internal printing repository

For example, a media company creates many images every day. However, the company cannot stream this data to the cloud constantly because of network latency. Instead, it uses a high-end NAS device to store the photos. Any employee can access and edit these photos over the company network.

What are the components of a NAS device?

NAS devices are typically made up of several components.

Physical storage drives

NAS devices can contain from two to five hard drives, which gives them high-volume storage capacity. Multiple physical drives are arranged logically as redundant storage containers (RAID). RAID is a virtualization technology that combines multiple physical storage components into one or more logical units. This helps back up data and improve performance.

Central processing unit (CPU)

NAS devices have a CPU that provides computing intelligence and power to manage the file system. The CPU reads and writes data to process and serve files, manage multiple users, and integrate with the cloud if desired.

Operating system

An operating system is a software interface between the storage device hardware and its user.. Although complex network-attached storage devices come with their own operating systems, some simpler devices may not have one.

Networking interface

The NAS unit connects to the network by using the networking interface. The network connection can be an ethernet cable or Wi-Fi. Many NAS devices also have USB ports for charging or to connect other devices to the NAS device.

What is the basic storage principle of NAS devices?

NAS is network attached storage for file based data. There are three main storage methodologies:

1. File storage

In file storage, you can store data in files, organize files into folders, and place them under a hierarchy of directories and subdirectories. It is a popular and familiar storage technique.

2. Block storage 

Block storage breaks a file into smaller chunks (or blocks) and stores each block separately under a unique address. The computer can store blocks anywhere on the device. The server's operating system uses the unique address to reassemble the blocks into the file. This is faster than looking through hierarchies to access a file.

3. Object storage

Objects are discrete units of data that are stored without a hierarchy or structure. Each object includes the data, descriptive information about the data (metadata), and a unique identifying number. Using this information, system software can find and access the object.

File vs. block vs. object storage 

Each storage type can be used in different ways. For example, file storage for local file sharing, and block storage for high-performance applications. On the other hand, you can use object storage to store unstructured data like email, videos, image files, web pages, and sensor data produced by the Internet of Things (IoT).

How does NAS work?

NAS systems combine hardware and software with protocols (or rules) to support file sharing over the network. By following these protocols, any computer can seamlessly access files from the NAS device as if the files were stored on the computer itself.

Communication protocols

Networks can run multiple data transfer protocols, but most networks have internet protocol (IP) and transmission control protocol (TCP). IP is the part that obtains the address to send file data. After that, TCP delivers the data by combining it into packets and sending the packets through the network.

File formatting protocols

Machines in a computer network can have different underlying operating systems, like Windows, Linux, or Unix. All of them want to access the NAS file storage in their native file format. Therefore, NAS file systems format the data before sending it to the network. The formatting protocols for file serving include:

Network File Systems (NFS)

Linux and UNIX systems use this protocol. NFS works on any hardware, OS, or network architecture.

Server Message Blocks (SMB)

Microsoft Windows machines use this protocol.

Apple Filing Protocol (AFP)

This is a proprietary protocol for Apple devices running macOS.

What are the different types of NAS devices?

Server based NAS

NAS servers are devices you use to set up on-prem file storage. They come in various sizes and types. For example, you can buy desktop units or rack mounted NAS server units. You can control and configure them over a network.

Scale up NAS

Scale-up NAS devices consist of storage drives managed by a pair of controllers. Every time you require more storage capacity you buy more NAS drives. However, the controllers do have performance and capacity limits. They can optimally manage only a fixed number of drives. Once the limit is reached, you have to purchase a new scale up device. This results in two independent silos of file storage. You have to manually distribute and manage your file data between both silos, resulting in increased overheads

Scale out NAS

Scale out NAS devices contain server groups that offer logical unit numbers or file shares over a network. They also have controllers and drives. However, the controllers can link multiple physical units to ensure they function as one logical unit. The system scales linearly and performance increases as you add capacity.

How does NAS compare to other storage network architectures?

NAS is one among other network storage solutions.

Storage area networks

A storage area network (SAN) is a dedicated high-speed network that interconnects multiple servers with a vast range of storage devices. Organization use SAN to centrally access, replicate, and protect all their storage as a single collective resource. SAN also uses additional technologies, such as RAID and data deduplication to optimize storage capacity and reliability.


Both NAS and SAN are networked storage systems. They pool storage capacity and share it with application servers over a high-speed network. The main difference between them is how the user perceives them. To clients, NAS works as a file system and SAN works as the operating system. NAS handles individual file requests, but SAN manages requests for contiguous blocks of data. NAS and SAN also use different underlying protocols and technologies. SAN is more flexible for users, but it can cost more to set up and manage. 

Direct-attached storage

Direct-attached storage (DAS) is storage that can be directly attached to a server device. The most common example of DAS is a cable-connected external hard drive. Only the host server can access the data directly. Other devices have to request data from the host device.


DAS is the precursor to NAS. DAS attaches directly to servers so the expansion slots in the server constrain both its scale and connectivity. DAS size also restricts storage capacity, and limits it to a small number of ports or host connections. It does not lend itself well to sharing and is complex to manage.

What are the limitations of on-premises NAS?

NAS is limited by its inability to deliver performance at scale.

Management Complexity

Maintaining on-premises NAS infrastructure can increase operational burden and drain IT budgets for organizations with budget and resource

Difficult to scale quickly 

NAS devices rely on hard disk drives (HDDs) to serve data. Unfortunately, if too many users send file requests at the same time, it can overwhelm the NAS system.  challenges.

No service guarantees

NAS devices can’t offer any storage service guarantees. Users could have problems like data lag, missing data, and lost data. NAS devices are not always reliable enough to use for mission-critical operations.

How can users overcome NAS limitations?

You can overcome NAS limitations by adding more NAS devices to the network, integrating with SAN, or replacing NAS devices with cloud storage. Let's explore the options below:

Add more NAS devices

To increase storage capacity, you can either scale up or scale out NAS architecture. Scaling up means using storage controller software to manage multiple physical drives on the same NAS server. Scaling out means using a common software communication interface called API to manage multiple NAS servers. By scaling out, organizations can make space for billions of files. However, it is costly to configure, code, and manage.

Unified storage

Despite their differences, SAN and NAS are not mutually exclusive. You can combine them to form a SAN-NAS hybrid, which gives you both file-level and block-level protocols from the same system. You can also run NAS on top of a SAN system to get filesystem services. You can find devices with hybrid SAN/NAS components in the market.

Cloud storage

You can augment or replace physical NAS by using cloud-based file storage. A cloud gateway at the edge of a company's data center network moves application data between local storage and the public cloud. A cloud provider manages and operates the data storage as a service. You can access storage on demand with just-in-time capacity and costs, eliminating the need to buy and manage your own data storage infrastructure. Cloud storage gives you agility, global scale, and durability with any time, anywhere data access.

How can AWS help with storage solutions?

  • Amazon Elastic Block Store (Amazon EBS) offers cloud-based, block storage services. You can migrate on-premises SAN workloads to the cloud for mission-critical applications. EBS stores data at a lower cost without compromising performance.
  • Amazon Elastic File System (Amazon EFS) is a simple, serverless, set-and-forget file system for AWS compute services. You can securely and reliably access files and scale or shrink storage as required.
  • Amazon FSx for NetApp ONTAP provides fully managed highly reliable, scalable, performant, fully managed shared storage for Linux, Windows, and MacOS workloads.
  • Amazon FSx for OpenZFS offers fully managed shared file storage built on the OpenZFS file system, powered by the AWS Graviton family of processors, and accessible via the NFS protocol (v3, v4, v4.1, v4.2).
  • Amazon FSx for Windows File Server provides fully managed shared storage built on Windows Server.
  • Amazon Simple Storage Service (Amazon S3) is an object storage service that offers industry-leading scalability, data availability, security, and performance.
  • Amazon Virtual Private Cloud (Amazon VPC) gives you full control over your virtual networking environment, including resource placement, connectivity, and security.
  • AWS Storage Gateway provides on-premises applications with access to virtually unlimited cloud storage.
  • AWS Storage Services offers a complete range of services to store, access, control, and analyze data.
  • Get access to free Cloud Storage by opening an AWS Account today!

Next steps on AWS

Check out additional product-related resources
Learn more about storage services 
Sign up for a free account

Instant get access to the AWS Free Tier.

Sign up 
Start building in the console

Get started building with AWS in the AWS management console.

Sign in