The Ultimate Guide to Network Attached Storage

Network Attached Storage (NAS) is a great way to store, share, and protect small business data. Before you invest in a NAS storage appliance, however, you should consider whether a given device has the right mix of capacity, redundancy, connectivity and other capabilities to meet your needs.

How to Buy Network Attached Storage

Here’s what to look for when shopping for your next small business NAS.

Storage Capacity

You’re investing in NAS for the long haul, and the last thing you want is your NAS running low on space in just a year or two. But how do you determine how much data a NAS box can hold, both now and in the future? To paraphrase a recent hit song, it’s all about the bays.

In a nutshell, more drive bays means more storage capacity. A NAS may have two bays, or four, or six, or more (sometimes lots more), but when you consider that the biggest commonly available hard drive is currently 6 TB (although 8 TB drives are emerging), some simple math gives you the maximum capacity of a given NAS unit (e.g. 4 bays x 6 TB = 24 TB total storage).

Synology DX513 NAS

Some NAS devices, such as the Synology DX513, offer an expansion chassis, which lets you expand the number of drive bays.

It’s not quite that simple though, because data redundancy via RAID (which we’ll talk about next) cuts your usable storage by as much as 50 percent. Suffice it to say that aside from choosing a NAS with enough capacity to meet your immediate needs and to accommodate redundancy, getting a model with some unused bays is the best way to ensure maximum flexibility—and minimum hassle and cost—with regard to future expandability.  That is, unless you opt for a model that lets you add more bays via an expansion chassis such as the Synology DX513

Data Redundancy

Although you’re certainly going to want to back up all the data stored on your NAS (more on that later), your first line of defense against data loss is RAID, which spreads your data out across multiple drives to protect against the failure of a drive. RAID comes in several flavors (1, 5, and 6 are the most common), and the one you choose depends on how many drives you have and how much storage you’re willing to sacrifice for redundancy.

See the link above for more detail on the various RAID levels (ignore 2, 3, and 4, which are obsolete), but as an example, RAID 1 mirrors the contents of one drive to another, so if you have a pair of 2 TB drives your usable storage capacity remains 2 TB. RAID 5, which requires at least three drives, uses the equivalent of one drive for data redundancy, meaning that you forgo a third of your total capacity in a 3-drive setup and a quarter of it in a four-drive scenario. (Again using 2 TBs drive as an example, that would mean 4 TB usable for the former and 6 TB for the latter.)

Then there’s RAID 6, which requires a minimum of four drives and uses the equivalent of two of them for data redundancy (so it can survive the failure of two drives instead of just one). Thus, four 2 TB drives in a RAID 6 configuration provide 4 TB of storage, while five drives will yield 6 TB.

It’s also worth noting that standard RAID technology requires all drives to be of identical capacity, which is an important fact to consider both when purchasing a NAS and for future storage expansion. (Technically you can use different-sized drives in a RAID, but the smallest one will determine how much of each drive is actually used.) That said, some NAS vendors—two being Drobo and Synology—offer specialized forms of RAID that do let you mix-and-match different drive sizes (and use all the storage they provide).

Westernn Digital MyCloud DL4100

WD’s MyCloud DL4100 has dual power supplies that let the unit keep running even if one fails.

For times when a drive goes bad, it’s best if a NAS supports hot-swapping (so that you can replace the bad drive without powering down the unit), or a hot spare (an extra drive that runs unused in the device until its needed). For quick and easy replacement, NAS devices should not need drives to be mounted in trays, or at the very least not require tools to do so. 

Speaking of redundancy, hard drives aren’t the only things in a NAS that can go bad. Power supplies (which generate a lot of heat) are known to fail too, and unlike a bad hard drive, a busted power supply stops a NAS dead in its tracks. You can minimize the risk of downtime with a NAS that sports dual power supplies, such as the WD MyCloud DL4100 (or pick up an extra power supply along with your NAS so you’ll have a spare on hand).

Network Connectivity

A NAS device’s network connectivity features will determine how fast you can get data on and off the device. For starters, forget about Wi-Fi—even modern 802.11ac isn’t fast (or robust) enough to keep up with the throughput of a SATA hard drive, much less multiple drives running in parallel. That’s why most NAS devices don’t include Wi-Fi support (though some support via an add-on.)

At a bare minimum you’ll want your NAS to sport a pair of GbE (Gigabit Ethernet) ports; most NAS devices with multiple Ethernet ports let you configure them for aggregation (combining their capacity for better performance) or  failover (which allows the unit to stay connected to the network if a port goes bad). Some NAS models include up to four GbE ports (such as the Synology DS1815+), and higher-end models may offer even speedier 10 GbE (10 Gigabit) ports, and/or a path to upgrade to them (the QNAP TS-563 or the Netgear ReadyNAS RN716X, for example).


QNAP’s TS-563 has two GbE ports, upgradable to either 4 GbE or 2 10GbE ports.

You should also consider how many and what kind of USB ports a NAS has. Most NAS devices still include at least a few USB 2.0 ports, but the best ones provide mostly USB 3.0 ports, which are 10 times faster (and comes in handy when you want to transfer to/from external storage quickly). And if your NAS is going to be in a rack or another confined space you’ll want at least one front-mounted port for easy access.   

Data Backup and Remote Access

As we mentioned earlier, don’t consider RAID a substitute for backing up your data. Backing up NAS data to an external hard drive isn’t as practical as it once was given that NAS capacities can now easily outstrip the 6 or 8 TB of the largest hard drives. Thus, be sure to check how a prospective NAS handles backup. Many NAS devices will replicate their contents to a second NAS device (often in another location) and/or backup to various cloud storage services such as Amazon, Google, Microsoft, and others.

These days the notion that you’ll need to access a NAS only from within the confines of an office seems almost quaint. Almost every NAS vendor offers remote access to data as a checklist item, but they implement the feature differently (i.e. how to setup and use), so if remote access is important to you, be sure to research how a given NAS device handles it before you buy. (Here’s how QNAP, Synology, and Seagate do it, for example.)  

NAS Features and Apps

NAS devices once handled basic file sharing and not much else, but modern NAS devices are much more sophisticated, offering a host of integrated features as well as (typically free) downloadable apps that let you add even more capability post-purchase. Today’s NAS devices frequently offer built-in or add-on features including media organization and streaming, surveillance camera management, even email, RADIUS, and VPN servers.

Make sure that the features on a NAS device match your business needs, and one feature in particular that’s worth seeking out is anti-virus. Without it, the only way to keep your NAS data free of infection is to regularly scan it from a PC.  

Carefully consider the options above, and a NAS box will serve your small business well for many years to come.

Joseph Moran is a technology writer and IT consultant who specializes in services for consumers and small businesses. He’s written extensively for numerous print and online publications, and is the co-author of two previous books on Windows.

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