NAS vs. SAN: Understanding the key differences

What is NAS (network-attached storage)?

Network-attached storage, or NAS, is a data storage system in which one centralized storage device connects to a local area network (LAN) made up of a network switch and one or more user machines. Each machine on the network can add and retrieve data on the central NAS storage machine as long as they are all routing data through the same network switch.

From the user side, the NAS storage is a shared folder. Files can be uploaded to the folder, viewed, or downloaded. Once a device is added to the network, a user can immediately start sharing data with other networked devices.

NAS devices often use file-sharing protocols like NFS, SMB, and CIFS and often rely on Ethernet cables to link the NAS machine to the local network. The NAS hardware itself usually consists of a machine with space to insert multiple drives, each of which can store data. Adding more drives (also known as volumes) or upgrading to a device with more drive capacity can increase storage.

NAS is a popular storage solution for several reasons, though ease of use is probably its primary selling point.

What are the advantages of NAS?

NAS is a good option for individuals and small businesses because it’s easy to deploy and maintain and is relatively affordable. These systems don’t require a lot of technical experience to set up, and the hardware usually comes with an easy-to-use software portal for management. If you want to back up your home files or share data within a small team, NAS should fulfill your needs.

To a limited extent, NAS is also scalable because more volumes (or new volumes with greater storage capacity) can be added to the machine over time. You’ll run into some limitations if you want to scale the network dramatically, however, which brings us to the downsides of NAS.

What are the disadvantages of NAS?

NAS has its limitations, specifically when it comes to scaling. You might be able to increase storage with some new volumes, but eventually, if you want more space, you’ll have to upgrade the entire NAS machine to something with more storage and processing power.

Even if storage capacity itself isn’t a problem, performance will start to degrade if multiple users are added to the network or if large file formats (raw video footage, for example) are being stored and retrieved. No matter how powerful the NAS machine is, it’s still one centralized database, so the more people access it, the slower its Ethernet connection will be.

The fact that NAS usually relies on Ethernet also causes problems. When traveling via Ethernet, data is broken down into packets and forwarded individually. This approach doesn’t lend itself well to uploading or downloading bigger files and is prone to packet loss.

Ultimately, NAS is just not intended for use at scale. It’s perfect as a home storage solution or for small businesses, but in larger operations, SAN is better.

What is SAN (storage area network)?

A storage area network, or SAN, is a storage network that prioritizes speed, scalability, and data integrity. In SAN systems, multiple storage devices (also referred to as storage blocks, or block storage units), servers, and user devices are connected over a high-speed network, often using the Fibre Channel (FC) protocol. Other popular SAN protocols include Fiber Channel over Ethernet (FCoE) and iSCSI (Internet Small Computer System Interface).

The FC protocol ensures in-order delivery (if data is not delivered in the correct order, the transmission is canceled and resent) and lossless transmission (if data goes missing during transfer, retransmission occurs). Because of FC, SAN is a much better option for storing data in large file formats than NAS. SAN is similar to direct attached storage (DAS) but is easier to manage from an administrator’s side.

What are the advantages of SAN?

SAN offers two key advantages. The system is faster and more reliable for storing and retrieving data, and it can scale dramatically over time.

First, let’s talk about their speed and performance. Because a SAN setup links user devices, the SAN server, and the storage databases through an FC network, users have direct block access. That means they can access stored files as if they were connecting directly to the databases, instead of routing through the wider network.

Even if the local network as a whole is experiencing high levels of traffic (unrelated to the storage resources), data being sent to and from SAN databases won’t suffer from latency or congestion. A SAN system operates almost like a subnetwork (consisting of user machines and storage devices) within the larger network.

When it comes to scalability, SANs excel because you can add new blocks whenever you wish to. Unlike a NAS system, in which one central storage device services all networked machines, SAN architecture can include as many databases as you choose to add. This, combined with the speed of the FC network, makes SAN a great choice for large organizations.

What are the disadvantages of SAN?

SAN is complicated to set up and maintain, and the hardware needed is expensive. While NAS can be set up by one person in their home, SAN requires experienced administrators to deploy and monitor it over time.

To properly implement a SAN system, a separate ethernet network has to be set up to handle metadata file requests. This, combined with the deployment of the FC network, will be costly, making it a less desirable option for small businesses and home users.

Despite these negatives, large organizations, especially those with a need to scale indefinitely, will benefit from SAN. The problems inherent in a SAN approach will be less of an issue for a large enterprise with a preestablished IT support team and a bigger budget.

NAS vs. SAN

The differences between NAS and SAN come down to their architectures, use cases, and how they handle data. Take a look at how they compare:

NAS is easier to implement than SAN because it requires less technical know-how and a simpler deployment. SAN is a more complex solution and relies on extra Ethernet and FC networks to function.

While NAS is ideal for smaller file storage and data sharing, SAN is designed for handling large file formats and scaling to accommodate more users and data over time. NAS should be perfectly adequate for managing basic files within a small team, whereas SAN is more reliable when it comes to managing mission-critical stored data.

A NAS device will always be less expensive to deploy and maintain than a SAN. However, because SANs are typically used by enterprise-scale organizations, and NAS by small teams and individual users, the cost isn’t a major problem.