Network attached storage (NAS)
Like the name suggests, these are hard drives that can be plugged directly in to your home (or office) network's router. They are the best solution for sharing storage across multiple computers, including desktops, laptops, and even things such as tablets and smartphones. You need a good router for the NAS to connect to, and the interface is Ethernet, usually of the Gigabit variety.
A NAS device requires a bit more know-how to set up and use compared to a regular external hard drive, primarily because you need to have a functioning home network and an idea about how to access and configure a network drive once it's on your network. Luckily, many NAS devices on the market these days come with tools that can allow you to find and install the drives with relative ease, so the learning curve is not a steep one.
With a NAS device, you may also need to fiddle around a bit more with the physical installation. While vendors such as Seagate and WD supply NAS devices that come in pre-configured capacities, the usual form for other vendors, such as Asustor, Qnap, Synology, and Thecus, is that you buy only the case, which is empty, and then install the hard drives of your choice yourself.
Your buying decision in such a scenario will have to include how many drive bays you want. The more drive bays (up to four is most common for consumer NAS devices, though six and eight are available, too), the higher the capacity you can install. Two drive bays should be the minimum that you go for, though drives with one bay also exist if you want the simplest installation experience.
If you are going for an empty NAS, then you will need to buy 3.5in hard drives of the capacity of your choice and follow the recommended NAS vendor's instructions on how to properly install them physically, and then how to set them up after that. You can install only one drive (even in a multi-bay drive), but it is recommended that you install two or more in order to keep your data safe.
Since most NAS devices have two or more bays, it is typical for a NAS device to support RAID arrays, with RAID 1 being the recommend array for a NAS device with two drive bays. What RAID 1 does is mirror your data on both drives. If one drive dies, then your data is not lost and you can replace that dead drive and rebuild the array to keep protecting your data. If you were using RAID 0, which stripes your data across both drives for the purpose of speed, then a faulty drive would leave your data lost forever.
Note that with a RAID 1 array, your total capacity will be halved. If you install two 4TB hard drives, instead of getting a full 8TB, you will get 4TB as one drive will be used for data duplication. It is the price to pay for protecting your data. It used to be said that you should match the make and model of drives in your NAS device. These days it is common to mix and match vendors and models to minimise the chances of buying two drives that can develop the same fault. There are also dedicated NAS hard drives these days, from both Seagate and WD, which are optimised for use in a NAS device.
You should buy matching disk capacities in order to make the most of the total capacity. For example, if you buy one 4TB drive and one 2TB drive, a RAID 1 array will only let you use 2TB, thereby making that extra 2TB go to waste. Buy the same capacity for both drives, and that maximum will be used in RAID 0. Mixing capacities works in a mode called JBOD (just a bunch of disks), but you don't get data redundancy.
While a NAS device is perfect for storing and backing up data from anywhere on your home network, the other thing to note about NAS devices is that they can be used for a vast array of other purposes. A lot of advanced devices now have built-in download managers, support for VPN, as well as things such as media server support (for streaming to mobile devices, smart TVs, and consoles) and can even serve blogging platforms such as Wordpress.
In many instances, they can also be accessed and managed conveniently from a mobile device, and you can even stream content from a NAS to a mobile device quite easily if it has a supported file manager (otherwise you can use a third-party file manager such as ES File manager for Android to find content on your network).
You should implement a NAS device for your home or office network if you want the ability to manage and share storage capacity and files across multiple computers and mobile devices on your network. It requires a bit more legwork than a typical external hard drive, but the extra functions and the ability to expand the capacity, and to make data redundant in case of failure, mean they are more valuable than external hard drives.
Wireless portable hard drives
While we're on the network theme, a wireless portable hard drive is basically a network-capable drive that you can use while on the road. It is a typical-looking portable hard drive, though perhaps a little thicker or longer due to it having built-in Wi-Fi capabilities, and its capacity can be similar to that of a standard portable drive -- that is, enough to store heaps of movies and music.
A wireless portable hard drive emits its own wireless network, and is primarily designed to facilitate the streaming of content to mobile devices, be it tablets or smartphones, both of the Android or iOS variety. There is usually enough bandwidth to support the transfer of up to a handful of movie streams (in Full HD), and this can come in handy for families on road trips who want to give their kids access to content for them to stream on their tablets without tapping into mobile data plans.
The signal range of a wireless portable drive is not great, and it should only be used with mobile devices that are in close proximity. Setting up a wireless drive often requires connecting to the hard drive directly, following the instructions the vendor has set out for this procedure. Generally, it can cut off Internet access to a mobile device unless there is a pass-through Internet feature in the drive.
You can also use a wireless portable hard drive for the purposes of backing up the data on your mobile device.
These are essentially NAS devices that plug in to your network, but which are marketed to highlight the fact that they are tailored for use over the Internet. A Cloud-enabled drive generally offers a simple Web-based service that can allow you to log in to your hard drive from anywhere you have an Internet connection, but you must sign up for the service (it's usually free and it doesn't store your data, only the location of your drive -- your data remains on your drive).
A drive like this can make it possible for you to access work files remotely, or even to log in to your drive so that you can manage its settings or set up downloads. In most cases, you don't have to know anything about how to set up remote access, or how to configure your router for such a scenario -- the hard drive and the hard drive vendor's service will take care of all the configuration details and all you will have to do is log in to that service via a Web browser or app.
Regular NAS drives can be set up for remote access as well, with some vendors providing their own services for such a task, while others require you to set up your own dynamic DNS service in order to make the drive accessible over the Internet.
Next: On-the-go USB drives and reviews list