What Is a NAS? Network Attached Storage Explained
Network attached storage (NAS) is a dedicated storage device connected to your network that gives multiple users and devices centralized access to shared files. Unlike a typical external drive plugged into one computer, a NAS runs its own operating system and manages user permissions. Authorized users and devices can then access shared files over the network without relying on another user's computer.
For growing businesses, a NAS solves a common problem. Employees often save files to individual laptops, scattered external drives, or multiple cloud services, making shared files harder to organize and find. A NAS gives an office one centralized location for shared files, backups, and media that the business owns and manages directly.
This guide explains what a NAS is, how it works, and how it compares with cloud storage, direct attached storage, and storage area networks. It also covers what businesses typically use a NAS for and what network infrastructure it needs for reliable performance.
Key Takeaways
- A NAS is a dedicated storage device connected to your network that gives multiple users centralized access to shared files.
- A NAS combines physical drives, an operating system that manages access and permissions, and, on multi-drive systems, RAID or similar technology for redundancy.
- A NAS differs from cloud storage, DAS, and SAN in ownership, cost, and network access.
- Common uses include centralized file sharing, automated backups, media storage, and hosting for business environments.
- A NAS performs only as well as its storage and network: wired throughput and link aggregation can affect performance, while network segmentation and access-control policies help protect storage traffic.
What Is Network Attached Storage (NAS)?
A NAS is a dedicated device with its own storage and operating system that connects to your network. This lets multiple users and devices access files centrally, rather than files living on one person's computer. The term "NAS" refers to both the physical device and the general approach, and it's sometimes used interchangeably with NAS server or NAS device.
A common alternative for small businesses is an external hard drive plugged into one employee's computer. That drive is only available to other users when the computer it's connected to is on. Sharing files can then require employees to request access or copy them manually. A NAS removes that bottleneck by putting shared storage directly on the network, where authorized users and devices can access it.
How Does a NAS Work?
A NAS combines storage drives, an operating system, and network connectivity to provide centralized file access. Multi-drive NAS systems can also use RAID (redundant array of independent disks) or other redundancy technologies to protect against drive failure. A NAS typically connects to the local network over Ethernet, much like a computer or printer.
The Hardware (Drives and Bays)
A NAS chassis contains one or more drive bays. Many business models use hot-swappable bays, letting an administrator replace a failed drive without powering down the device. Capacity can scale by adding drives when bays are available, replacing drives with higher-capacity models, or adding expansion units on supported systems.
RAID (Redundant Array of Independent Disks) and Data Redundancy
RAID combines multiple physical drives into a logical storage configuration, with different RAID levels providing different combinations of capacity, performance, and redundancy. Many multi-drive NAS systems use RAID to provide redundancy if a drive fails, with the level of protection depending on the RAID configuration. RAID is not a substitute for backups: it guards against hardware failure, not accidental deletion, ransomware, or a disaster affecting the whole device.
The NAS Operating System
The NAS operating system manages user accounts, permissions, and file sharing over common network file protocols such as SMB (Server Message Block) and NFS (Network File System). These are the same protocols computers use to access shared folders on network file servers. It also typically runs additional services, such as backup scheduling, media indexing, or surveillance recording.
How a NAS Connects to the Network
A NAS typically connects to the network through an Ethernet port on a switch, the same way any other wired device joins the network. Every file request, whether from a desktop across the office or a laptop connected over Wi-Fi, travels across the network to the NAS. The switch, network links, and cabling behind the NAS can all affect file-transfer performance.
NAS vs. Cloud Storage, DAS, and SAN
The key differences between NAS, cloud storage, DAS, and SAN come down to control, cost, and scale. Direct attached storage (DAS) is best for storage directly attached to an individual computer or server, while NAS suits centralized file sharing across a network. Cloud storage works well for storing data with a cloud provider without managing local storage hardware. A storage area network (SAN) fits block-level storage in larger or performance-sensitive environments.
| Storage Type | How It's Accessed | Where Data Lives | Best Suited For | Cost Model |
|---|---|---|---|---|
| NAS | File-level access over the local network (SMB or NFS) | Typically on-premises, owned by the business | Centralized file sharing for multiple users and devices | Primarily upfront hardware cost |
| Cloud Storage | File-level access over the internet or a private network connection | Off-site, hosted by a cloud provider | Off-site storage without managing local hardware | Recurring or usage-based fees |
| DAS | Direct connection to a computer or server (such as USB or SAS) | Local to and directly attached to the host | Storage for an individual computer or server | Primarily upfront hardware cost |
| SAN | Block-level access over a dedicated storage network | Typically on-premises, owned by the business | Block storage for larger or performance-sensitive environments | Higher upfront infrastructure cost |
NAS vs. Cloud Storage
A NAS typically requires an upfront hardware investment that the business owns outright, while cloud storage generally charges recurring or usage-based fees for hosted capacity. A NAS can remain accessible over the local network during an internet outage, while accessing cloud-hosted files generally requires connectivity to the cloud service.
NAS vs. DAS (Direct Attached Storage)
DAS connects directly to a computer or server, while a NAS connects to the network and provides shared access to multiple authorized users and devices. For a business with more than one employee needing shared files, that network-wide access is a key reason to choose NAS over DAS.
NAS vs. SAN (Storage Area Network)
A SAN provides block-level storage over a dedicated storage network, functioning more like a raw disk that connected servers manage directly. A NAS instead provides file-level access through network file protocols. For many small and midsize businesses, NAS provides the file-level shared storage they need with less infrastructure and complexity than a typical SAN deployment.
What Is a NAS Used For?
Businesses deploy a NAS for centralized file sharing. A design team, sales team, or back office can then work from the same documents without emailing versions back and forth. Automated backups are another common use, with a NAS storing scheduled copies of files from business computers and servers in a centralized location.
A NAS also commonly stores media libraries and archived project files, and businesses running IP cameras can use NAS devices to store recorded surveillance footage. For a small office, one NAS device can consolidate file sharing, backups, and archived data into a single piece of infrastructure the whole team uses.
The Network Behind a Fast, Reliable NAS
A NAS's performance depends on both the storage system and the network connecting it to users, since file requests must travel across that network. Three network considerations matter most for business NAS deployments: wired throughput, aggregate capacity for simultaneous users, and traffic segmentation.
Wired Throughput and Multi-Gig
A standard 1 Gbps connection has a theoretical maximum of 125 MB per second, though real-world throughput after protocol overhead typically lands closer to 110–120 MB per second. That can bottleneck a multi-drive NAS capable of sustained transfer rates beyond this ceiling. Connecting a NAS with its own multi-gig-capable network interface, such as 2.5GbE or 10GbE, can increase available network bandwidth for large transfers and backups. The switch port needs to support at least that same speed for the connection to see any benefit. Select Omada managed switches include 2.5G or 10G ports built for connecting higher-throughput devices like a NAS.
Supporting Multiple Simultaneous Users
When several employees access the same NAS at once, the network needs enough aggregate capacity to carry their traffic without creating a bottleneck. Link aggregation combines multiple physical switch ports into one logical connection, increasing aggregate bandwidth and providing redundancy between the NAS and the network.
Choose switches with link aggregation support when the NAS and network are both configured for it. This can increase aggregate bandwidth across multiple traffic flows, reducing the risk of the NAS link becoming a bottleneck as usage grows. Select Omada switches support link aggregation, including LACP on supported models.
Segmenting Storage Traffic with VLANs
A virtual local area network (VLAN) creates a separate broadcast domain at Layer 2, grouping devices logically rather than by physical location. Placing the NAS on its own VLAN puts it in a separate broadcast domain from guest Wi-Fi, IoT devices, and other segments, reducing unnecessary broadcast traffic. Reaching the NAS from other VLANs requires inter-VLAN routing, typically provided by a router or Layer 3 switch. Access control lists (ACLs) or firewall policies can then control which segments are allowed to reach the NAS, adding a layer of access control on top of that broadcast-domain separation.
Omada's guide to configuring VLANs on an Omada network explains the setup process. Pairing wired VLAN segmentation with segmented Wi-Fi access keeps storage traffic separated across both the wired and wireless parts of the network. This typically means mapping each Wi-Fi SSID to the appropriate VLAN, so wireless clients are placed on the intended network segment.
Planning the Network Your NAS Needs
A NAS gives a business centralized, multi-user storage that it owns and manages directly. Its performance also depends on whether the network behind it can keep up. The drives and RAID configuration affect storage capacity and redundancy. The switch and network links affect performance, while VLANs and access-control policies affect network segmentation and security.
Before choosing a NAS, map out how many employees will access it at once and how large typical file transfers will be. Also consider whether storage traffic needs to be separated from guest or IoT devices. Reviewing Omada's multi-gig switching and VLAN segmentation resources is a practical next step for planning a network that supports a NAS as the business grows.
Frequently Asked Questions
What is a NAS in simple terms?
A NAS is a dedicated storage computer that stores files and makes them available to authorized users and devices on a network. It replaces the common practice of keeping shared files on one person's computer.
Is a NAS the same as cloud storage?
No. A NAS is typically hardware the business owns and keeps on-site, accessed over its local network. Cloud storage is hosted by a provider and accessed through a network connection, usually for recurring or usage-based fees.
Do I need a NAS for a small business?
It depends on how your team shares files today. If employees are emailing documents, relying on individual external drives, or managing files across multiple locations, a NAS can centralize storage and simplify file sharing.
What is the difference between a NAS and a server?
A NAS is purpose-built for file storage with a specialized operating system, while a general-purpose server can run a much wider range of applications. A NAS can be simpler to deploy and manage for businesses that primarily need shared storage and file services.
How much storage can a NAS hold?
Capacity depends on the number of drive bays, the capacity of the installed drives, and the storage configuration. Small NAS systems may provide several terabytes of usable capacity, while larger systems can provide well over 100 terabytes of usable capacity. Capacity can typically be expanded by adding or replacing drives on supported systems.
Does a NAS replace backups?
Not on its own. A NAS commonly runs backup jobs that copy files from other computers, and a redundant RAID configuration can protect against a drive failure. Neither RAID nor a backup stored only on the NAS protects against theft, fire, or ransomware that compromises the NAS itself.
What internet or network speed does a NAS need?
A NAS doesn't require an internet connection for local file sharing, but the network connection between the NAS and the switch affects local performance. A standard 1 Gbps connection is sufficient for many light workloads. A 2.5 Gbps or 10 Gbps connection can provide more bandwidth for large file transfers or multiple simultaneous users.
