These days, NAS devices are feature-loaded and can be used not only for centralised network storage, but as also as FTP, print, and web servers, as well as for multimedia streaming. Some can even be used to set users up with their own "personal clouds" for remote access and management, and NAS devices also offer things like social network integration, so users can publish video and images quickly to sites like Facebook and YouTube.
But what if someone doesn't need these extras? Some users only require what a NAS was originally intended for – namely, storing and accessing data across a local, or remote, network. For those users, USB-based NAS devices are a good option.
USB NASes differ from traditional HDD-based NASes in that they use external USB drives for centralised storage. This is why they are often marketed as "USB Adapters." Users connect external USB drives (most also support USB printers, as well) to USB ports on the NAS.
There are both advantages and disadvantages to USB NASes when compared to traditional HDD NASes, though, and we’ll look at the positive points first.
The biggest upside is that they are very affordable. You can get yourself a USB NAS for less than £30, in fact.
Typically, USB NASes are small devices as they don't contain hard drives. Since you have to use external USB drives, you want to factor the cost of drives in, of course. Drives can range from inexpensive memory sticks to large capacity USB drives, which can be costly (though you may already have an external disk drive or two at home already).
Since USB NAS devices are rather small, they can sit quite unobtrusively connected to a router. Because they use external devices for storage, USB NASes have virtually zero parts that are subject to hardware failure (besides the actual device as a whole), so they remain usable for a long time without requiring maintenance. Like HDD NASes, they usually work cross-platform and are happy with Windows, Mac or Linux machines and file systems.
Many of the USB NASes also have the same functionality as their HDD cousins. They can perform multimedia file streaming, work as file and print servers, and can be used to manage BitTorrent downloads. However, the feature set is not as extensive as you get with HDD NASes, but it’s still sufficient for lots of users. For instance, many HDD NASes have built-in user-friendly remote access methods, advanced security measures, and can act as web, print, and FTP servers.
One drawback when dealing with USB NASes is the limited storage options. With many HDD-based NASes, you not only have multiple hard drives, but you often have extra USB ports for more storage options. Business NASes also usually support iSCSI, allowing for even more scalable storage on a network.
You'll also take a performance hit with USB NASes. The Read/Write speeds of USB NAS drives simply can't compete with the SATA disk drives that traditional NASes house. If you are buying a NAS primarily for HD video streaming you'll want to think twice about purchasing a USB NAS (although most of them have streaming capability).
Ultimately, it’s up to you to weigh up those cons against the pros for your use case, and decide whether you can save some money and go for a USB NAS solution.