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DAS vs NAS: What is the difference?

Originally posted on techradar.

Understanding the options in storage

Data is essential to computing, and therefore keeping it safe is important. Having the data stored in a reliable fashion, and with efficiency is an essential task. In general, as data is created it is stored on the hard drive of the computer. However, that data is subject to loss, as it is only present as a single copy on that lone device. The solution to avoid loss of the data is to have it backed up.

There are two general ways to backup(opens in new tab) that copy of data, so that we can have a second copy elsewhere, in case the computer’s primary drive fails, or these is another technical issue with the computer. The first is direct attached storage (DAS), and the other option is network attached storage (NAS)(opens in new tab). Each has its own advantages and disadvantages, so it is worth taking a look at the best ways to use each.

What is direct attached storage?

Direct attached storage is quite simply storage attached to the computing device, also known as the host. This is the simpler, and also the cheaper of the two options, when compared to a NAS solution. Plenty of folks use DAS without even thinking about it, such as plugging in a USB drive(opens in new tab), or attaching an external hard drive(opens in new tab) via USB or eSATA.

As the drive gets connected directly, and it will work without being configured, explains why it is so simple to get up and running with. Drives are also pretty inexpensive, which explains the low startup cost for a DAS configuration. With DAS, there is no need to be connected to a network, and with the right enclosure, multiple drives can be housed in a single enclosure. Another advantage is that with a direct connection to the host, the transfer speeds and latency are quite favorable. Finally, there is little maintenance of this type of setup.

DAS is better suited for personal use, and to smaller and medium sized businesses. Data can be shared locally via a DAS solution, but this also becomes a downside when more users need access to the data. The problem also with DAS is that a given disk has a certain capacity that it was manufactured for, and that it has no ability to scale further. Therefore, with an expanding business, particularly one that is growing quickly and will need flexibility to scale, it is a poor choice as it will not be able to be grown, and rather work will be created as data will need to be migrated.

What is network attached storage?

The other option in comparison to DAS, is network attached storage, or NAS. As the name implies, rather than storing the data directly on an attached storage device, the data is sent through the network, and subsequently stored on a network device. While it is more complex to set up and manage than a DAS, its advantages explain why it is the more popular solution.

In a NAS configuration, the data gets sent across the local area network (LAN), to storage that is located a distance away from the host. One advantage of this is that the data can then be shared among a virtually unlimited number of users, making this useful for collaboration(opens in new tab) on a project.

Another plus is that with most direct storage, there is only a single copy of the data, such as with a USB drive. However, a NAS will support a RAID configuration, which can then have multiple drives that are mirroring the data. Furthermore, unlike with a DAS that cannot be scaled, NAS can easily scale with the option to add storage drives with the option for additional enclosures, or replace current drives with higher capacities as needs change. Through the years, NAS operating systems, such as Synology, have grown into mini servers(opens in new tab) that can also run an email server, extending their functionality even further.

Another difference between these two options is how the data gets accessed. With a DAS, the data is accessed by the sector, as it is directly off the storage medium, for example a hard drive(opens in new tab). However, in a NAS, the data gets accessed by file. This means that there needs to be a file structure set up; there are multiple possibilities to choose from such as NFS, AFP, or CIFS.

A downside is that it requires additional configuration, and it is more complex to get started with. However, there is also a benefit to having a file structure as it then becomes platform agnostic, and any device with any OS will have the ability to download the file and access it.

While there are many obvious advantages of NAS there are some disadvantages as well. The first is that NAS is dependent on a network, and if that LAN is slow, then the NAS will be bottlenecked, and therefore slow as well. Therefore, the network speed and latency should be accounted for in a NAS solution, and upgrades may be needed to Ethernet cables or Wi-Fi so it can handle the storage needs.

Another issue is that while NAS servers are usually designed to expand their storage, as they are a mini server, they have a CPU and RAM, and these are often not designed to be upgraded, so there may be a limited or even no pathway for upgrades down the road.

An additional downside of NAS encompasses that it is more costly than a DAS. This applies both to the hardware, and also for the configuration and ongoing maintenance expenses.


The DAS and NAS storage options both have their roles in a business. Users need to take into account the current, and anticipated future needs to select the right combination of storage devices to backup their data for current requirements, and also can further grow with them as needed. While we discussed each of them separately, many organizations benefit from using both DAS and NAS solutions simultaneously to cover all of their storage needs.

Source: techradar

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