Network Storage Comparison: DAS, NAS, and SAN

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In basic terms, network storage is any means of storing data that makes it available to clients over a network. The changing ways we use data and the exponential increase in the volume we collect and process have driven new ways to store and manage that data more effectively, and in practice, network storage now encompasses a wide range of technologies. This article is an introduction to the main types of network storage, both traditional and emerging.

In the days of mainframes, data was stored physically separate from the actual computer processing units but was only accessible through them. As PC-based servers became more commonplace, storage moved to internal drives built inside the PC itself, or to directly connected external drives. As the need to store increasing volumes of data and make it more immediately accessible grew, network storage came along as a better alternative.

Network storage refers to any type of storage that is connected to a network that lets users save and access their data. There are multiple types of network storage—here’s a look at the most common.

Direct attached storage, or DAS, is a storage device connected directly to a host system. The simplest example of DAS is the internal hard drive of a server or computer, though storage devices housed in an external box come under this banner as well. DAS is not networked. Instead, it is connected directly to a card on the computer’s bus interface using a peripheral connection like Small Computer System Interface (SCSI), Serial Advanced Technology Attachment (SATA), Serial-Attached SCSI (SAS), or Internet SCSI (iSCSI). This direct connection can make it both faster and simpler than network storage, but it’s also limiting. DAS cannot scale as easily, it can’t be shared, and it is less useful for backup and recovery. However, it’s the least expensive type of storage, and because of its speed, most physical servers still boot from DAS storage—even those connected to networks.

Network attached storage, or NAS, is a data storage mechanism that uses devices connected directly to the network. Rather than a peripheral connection, it uses a network connection like Ethernet or fibre channel switch. Each device is assigned an IP address that lets clients access it via a server that acts as a gateway to the data or, in some cases, allows the device to be accessed directly by the clients without an intermediary.

In an environment with many servers running different operating systems, NAS makes it possible for data storage to be centralized along with security, management, and backup. Early NAS devices were more likely to be CD-ROM towers—standalone boxes containing multiple CD-ROM drives—but today’s NAS devices use traditional magnetic hard drives or, increasingly, solid-state drives (SSDs).

NAS is easily scalable, and it brings an extra level of fault tolerance to the network. In a DAS environment, a server going down means that the data it holds is no longer available. With NAS, the data is still available on the network and accessible to clients. Fault tolerant measures such as RAID—an approach to deploying multiple drives in a configuration within a single array to provide reliability and security—can be used to ensure that the NAS device does not become a point of failure.

Learn about network attached storage security.

A SAN is a network of storage devices connected to each other and to a server or cluster of servers that acts as an access point to the SAN. In some configurations, a SAN is also connected to the network. SANs use special switches as a mechanism to connect the devices. These switches, which look like regular Ethernet networking switches, act as the connectivity point for SANs.

The ability for devices to communicate with each other on a separate network provides many advantages. Users can back up every piece of data on their network without having to “pollute” the main network infrastructure with gigabytes of data transfer, slowing down other traffic. SAN is expected to become the enterprise data storage technology of choice in the coming years.

Learn about SAN solutions for businesses.

While SAN and NAS are widely used types of network storage, they’re not the only way for enterprises to provide network-based access to data storage. Here are a few other competitive storage technologies.

Converged storage combines storage, computing, networking, and some management software essentials into a single, preconfigured system. This hardware-based approach is becoming more popular in mainstream data centers as they diverge from IT strategies that rely on traditional servers and networked storage. Because converged storage infrastructures centralize IT management, their usage is expanding. They’re also relatively easy to provision and scale, with reduced deployment times and costs and simplified management.

Similarly, hyper-converged storage infrastructure (HCI) also combines storage, computing, and networking into a single, highly virtualized system—one built on standard x86 computer hardware. Because a hyper-converged configuration removes the traditional data center components and replaces them with a single, virtualized appliance, it allows for easier upgrades and scaling by adding more nodes without the need to physically add hardware. This software-defined approach to systems and workload management makes for more agile and flexible operations.

Read about the top 9 hyper-converged infrastructure vendors.

Storage as a Service (STaaS) is another popular option competing with NAS and SAN solutions. Cloud storage vendors use service level agreements (SLAs) to guarantee customers a predetermined amount of uptime or availability using virtualization implemented on servers in multiple locations. By shielding the customer from the logistical nuances of the server operations, vendors provide a user-friendly interface with built-in automated processes allowing customers to provision virtual resources.

Learn more about STaaS.

Object-based storage is designed for storing unstructured data—emails, media and audio files, sensor data, and web pages, for example—rather than structured data. Most businesses have more of the former than the latter. Each stored object consists of the data itself, the metadata, and a unique identifier that applications use to access or retrieve it from storage. The ability to scale as needed is ideal for businesses that want to retain unstructured data, and object-based storage with an on-demand cloud service provider can facilitate granular data-driven decisions.

Learn more about object-based storage.

Network storage has been around for awhile, but it’s always evolving. New advances increase the available performance and capacity, expanding utility. Here are a few of the emerging technologies that are improving network storage:

The amount of data we collect, store, and process is growing, and the demand for fast, reliable, high-capacity storage solutions is growing in parallel. While direct attached storage is still a widely used solution—also a fast, affordable one—limitations around sharing and reliability mean enterprises of all sizes need better ways of storing critical data. Network attached storage devices are a viable solution well-suited to small and medium sized businesses, offering scalability and performance in an affordable package. Storage area networks can offer enterprises the scope and flexibility they need to support their data usage. These solutions are constantly evolving as new technologies increase their capacities and performance, and as demand grows, the market continues to offer new options to meet it.

Read next: 8 Best Enterprise NAS Devices for 2023