7 considerations before buying a NAS device

Things to consider before buying a NAS device
Image from datacenterknowledge.com.

Because of the costs involved, investing in a network-attached storage (NAS) device can be a daunting prospect. What makes it even more challenging is the fact that there are not many choices available in South Africa. 7 considerations before buying a NAS device is aimed at first time buyers who wants to cover all the important aspects before making a final decision.


A network-attached storage (NAS) device can be explained as a stand-alone device, connected to a network, that (typically) has a large amount of storage space (nowadays home NAS devices are hitting the upper tens of Terabyte figures). It is in the form of multiple hard drives, managed as one large drive. For more information, see a simple introduction to network-attached storage (NAS).

Stacked HDDs
A NAS is a device managing multiple hard drives as one. Image from startech.com.

Storage space

The most obvious factor to consider when buying a NAS device is storage space. More space is generally connected to more, or more expensive hard drives. Although the actual storage space is assumed to be a straight forward calculation, some RAID configurations with fewer hard drives will have relatively less usable space available – the rest will be occupied for redundancy (see later). The Synology website has a nice RAID space calculator.


Be prepared to pay a pretty price for a decent NAS device. Generally the price is dictated by quality, amount of hard drive bays and commercial availability. Aesthetics and orientation (see later) might also play a small part. In South Africa, an empty device (see below) is going to set you back at least a couple of grands. A proper, 4-bay NAS with hard drives will set you back at least ten. At the time of writing, anything below R 1000 per terabyte is a good deal.

0 TB or xx TB

Many NAS devices are marked as 0 TB. This actually means that only the NAS device (shell and CPU) is for sale, and does not include any hard drive(s). For those that has a few hard drives lying around at home, those can be used in stead. Devices without hard drives might, or might not be cheaper than those with hard drives.

Extra HDDs
Similar sized hard drives can be used in NAS devices. Image from blogs.voanews.com.

When this is the plan, it is important to note that hard drives need to be the correct physical size (3.5 in vs 2.5 in drives – NAS dependent), the correct minimum amount of drives are available (see later) and that all the drives are compatible with the specific NAS device. It is also better if the hard drives have the same amount of storage space.

With two or more hard drives, some RAID configurations will start to be an option (see below). Adding hard drives to a NAS system with a RAID configuration will need reformatting. Using a RAID configuration will also format different sized hard drives to the capacity of the lowest drive (i.e. using a 1 TB and a 2 TB hard drive together will be formatted to give about 2 TB of space, and not 3 TB).

Seagate BlackArmor NAS
The Seagate BlackArmor NAS device was available without hard drives and needed at least one hard drive to start off with.

In the case where a NAS system is already containing hard drives, one can likely rest assured that the hard drives are better suited for their specific device. Hard drives that are used by NAS device manufacturers are considered for their speed and and their reliability. Many hard drives are NAS optimised and are more suited for long working hours.

NAS devices that include hard drives are also generally sold at full capacity. There will be no additional bay slots to add more hard drives. If a RAID configuration is used, it might be a good idea to get at least one additional hard drive for in case one of the drives fail. Shopping around months to years later, might waste valuable time or be fruitless with regard to a similar size, brand or type of hard drive.

To RAID or not to RAID

RAID (redundant array of independent disks) is a way of storing the same data in different places on multiple hard drives. This is to protect data in the case of a drive failure. However, not all RAID configurations provide redundancy.

RAID 5 configuration
Visual representation of a RAID 5 configuration using 4 hard drives.

The RAID configuration used will be dependent on the needs of the network (not all data are equally valuable), the hardware capabilities of the NAS device and the amount of hard drives available. With a proper RAID configuration it is possible to loose the functionality of at least an entire hard drive without loosing its data. In the case of a defective hard drive it can simply be swabbed out with a new one and the system will continue to function. The more important RAID configurations can be summarised as follows:


  • Store data continuously (SPAN) or striped (RAID 0) over all the hard drives
  • Need 1 (SPAN), 2 (RAID 0), or more hard drives
  • With these RAID configurations, one can start with one hard drive and, over time, add more drives without having to reformat the system
  • Use the maximum available space
  • This configuration will not allow any redundancy. If one drive packs up, that drive’s data might be lost.

RAID 1/10

  • Store data equally on 2 (RAID 1) or 4 (RAID 10) hard drives
  • Best redundancy. If one (RAID 1) and up to two (RAID 10) drives fail, they can be replaced and the system will redistribute the data back onto the empty drive(s)
  • With these configurations you can only use about 50% of the total amount of space

RAID 6 (similar, but slightly better than RAID 5)

  • Stores a part of the total volume distributed over the total amount of hard drives
  • Some systems allow to add additional hard drives without having to reformat
  • Need 3 (RAID 5), 4 (RAID 6), or more hard drives
  • Good redundancy as you can still replace 1 (RAID 5) or 2 (RAID 6) drives without loosing any data
  • One will loose the amount of space of about one of the total amount of hard drives

Number of hard drives

With 1 hard drive only SPAN can be used. More hard drives can be added as time goes by.

With 2 hard drives RAID 0 or  RAID 1 can be used. More hard drives can be added with some NAS devices when using RAID 0.

With 3 hard drives RAID 5 can be used. More hard drives can be added with some NAS devices.

With 4 hard drives RAID 6 or RAID 10 can be used. More hard drives can be added when using RAID 6.

The NAS device also needs backups

When it comes to functionality, a NAS device can be divided into two major categories: the device itself and the hard drives. The idea of configuring the hard drives into a RAID level is to have some redundancy. The device itself, however, can also fail. In this case all the data on the hard drives needs to be transferred before the hard drives can be transferred to a different device. In South Africa, something like lighting surges can cause device damage while all the drives are still perfectly intact.

Cloud backup services
Some NAS devices now comes with easy-to-use cloud backup integration.

In other words, depending on the value of the data, NAS devices also need to be backed up from time to time. This is a case of “the bigger they are, the harder they fall”. Nowadays there are cloud backup solutions, but they become unpractical/expensive with larger amounts of data. DVD backups are probably even less practical. In an ideal world, two devices should be used – one a backup of the other. A more practical solution would be to save valuable data on ‘the cloud’ and spend less time and effort on less valuable data.


NAS devices range from rough looking, open rack systems to more aesthetic looking boxes. The orientation of the device might also be important to consider.

To make the device a little cheaper, the exterior of the device will often be neglected to focus more on the hardware and drives. On the other hand, some NAS device manufacturers also focus on the display of the unit. The enclosure of the Western Digital’s My Cloud series is in the form of an upright book. These units are neat to display in a shelve and fits in nicely with, for example, their My Book external hard drive enclosure series.

Horisontal NAS device
An example of a horizontal rack-mountable NAS device. Image from albates.com.

While some NAS devices stack the hard drives on top of each other, horizontal units are also available. Horizontal units can, for example, easily slip into flatter spaces or can even be mounted in a drawer or under a shelve or a table.


A last consideration, especially in South Africa, is the manufacturer’s and/or the product reputation. When buying online, make sure its reviews are favourable. If no reviews are available locally, sneak previews from, for example, YouTube, Amazon or other larger online shops.

About the author
Renier busies himself with improving his English writing, creative web design and his websites, photoshopping, micro-electronics, multiple genres of music, superhero movies and badass series.
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