Earlier this summer, I published We Got Served’s review of Western Digital’s brand-new WD Red 6TB NAS hard drive. As I mentioned in the feature, both WD and Seagate have been quick to niche their product line-ups, tailoring their core storage technologies with tweaks and value-added features to serve a wide variety of consumers.

In the course of writing the review, I was struck by the fact that for the average home server/NAS owner, selecting the right storage for your rig is more complicated that it ever has been. In the past, it was easy – you had consumer desktop drives and enterprise drives. Given the scarily-high prices of the latter, it was a simple choice.

But then came the so-called “green” drives – desktop drives with a low-power twist. Then the aforementioned NAS drives, “pro” drives for small business, drives for enterprises, drives for data centers, drives for surveillance equipment. Each with SATA 3 Gb/s and 6 Gb/s options. Sure, you could just go for the ones that say “NAS” right? That would save you a lot of time worrying about selecting the right drive, wouldn’t it? As the manufacturers have done the worrying for you!

But… really? Should you be paying a price premium for NAS storage, compared to standard desktop drives? Do those value-added features truly add value? And what are all those features anyway? Perhaps you shouldn’t be trusting your precious data to a consumer drive at all and invest in expensive small biz or enterprise drives instead? Surely the more you pay, the better the drive?

In this (reasonable exhaustive) feature, we’ll try out a swathe of hard drives on a number of test devices to compare how they perform. We’ll look at some new drives and as we know that many of our readers like to re-purpose old machines and older drives for their home servers, we’ve dug out a couple of old drives we had knocking around to add them to the mix too.

We’ll explore some of the features that the manufacturers market to convince you that their drives really are the right ones for you. Whilst I doubt very much that we’ll settle on a single model that we believe is right for every user and every server, in every situation, hopefully our exploration will help you on your own journey to find your chosen model.

Having spent the last seven years reading and writing about network attached storage, my promise to to make this comparison as simple and clear as possible. There will be benchmarks, but I’m not going to dive into every comparable stat imaginable – I’ll leave that to the more technical sites out there that really excel at the hardcore detail. Rather, I’ll look at the indicators that I think are most important in determining NAS performance – there are only a few, so no-one should be bamboozled by stats.

With that all said, let’s introduce our test subjects.

Our Test Hosts

I thought it would be useful to compare performance on a range of consumer and prosumer/small business devices – brand selection was based more on what devices I had available here at WGS rather than any specific intent, but I wanted to ensure we had a representative selection of devices released over the last couple of years.

So, you’ll find our test hosts include a basic, twin-bay device with a budget processor, a four-bay Intel Atom-based NAS, an Intel Core i5 Windows 8.1 PC and a rackmount ASUSTOR AS-609RS .

One important consideration for you when selecting your NAS or home server is the capacity of drives that a particular device supports. As we move into an era of huge hard drive capacities – 5 TB, 6 TB and beyond – you may find there’s a limitation on the maximum size of RAID array that a device supports, particularly at the lower end of the market. For example, you may assume that all modern four-bay NAS devices would support arrays of 24 TB (four x 6 TB drives), right? Wrong. Let’s pick a device such as ASUSTOR’s AS-304T – a reasonably new NAS device. Dig into the device’s specifications on the web, and you’ll see “due to system kernel limitations, the maximum capacity of a single RAID volume for this model is 16TB.” Obviously, other devices from ASUSTOR and others support arrays well in excess of 16 TB, but not all do.

So, while we’ll test drive sizes up to 6 TB on our test devices, do make sure to check any capacity limitations on your devices before deciding on your own choice of drives.

The Test Setup

To test performance, two of each hard drive model were installed in the NAS device/server and configured in a RAID 1 (mirrored) array. The server was connected to a production, real-world Gigabit network (no polished lab conditions here!) with an Apple Time Capsule acting as the router. We then measured network file transfers using an Intel NUC as the client PC. This device is powered by an Intel Core i5 processor and was running Windows 8.1 as the operating system.

The Hard Drives

We’ve selected nine drives of varying specification, size and age to benchmark on our test servers. They comprise standard desktop drives you’ll find in your local big-box electrical retailer, specialist NAS drives and drives for small business as well as drives intended for enterprise and datacenter use. Obviously it would be difficult (and dull) to test every drive from every manufacturer in the market, so take this as a representative sample of what’s available in stores (and stored away in cupboards at home).

Here’s the line-up:

For the uninitiated, the table above lists the manufacturer’s brand, model name and SKU (stock keeping unit – think of it as a product code that retailers use). I’ve also included the drive capacity (in terabytes), SATA connection speed (SATA stands for Serial ATA and is rated in gigabits per second – the maximum speed at which data is transferred through the hard drive’s physical connection to the motherboard), Cache size (embedded memory that’s used as a data buffer between the physical disk platters in your hard drive and the home server/NAS – rated in megabytes) and Spin speed (the speed of the drive’s disk rotation – measured in revolutions per minute). Faster rotation doesn’t necessarily mean faster transfer rates though and as you can imagine, the faster you spin a disk, the hotter it can get and the more power it may use.

SATA connection speed, Cache size and Spin speed can all have an influence on data transfer rates, so are generally used by manufacturers to classify their products at a high level. As we’ll see, there are many more features built into these drives that may also influence performance and reliability.

Let’s talk through the list by category.

Desktop Drives

We’ve picked out two desktop drives for our round-up. The  has been around for some time now (in fact, the company no longer use the well-known Barracuda product brand – it’s just Seagate Desktop Hard Drive) and I’m sure that most of you will have bumped into one of these drives at some point. It’s a 3 TB drive that connects to the NAS via a 6 Gb/s SATA connection. Like all of the drives on test, it includes a 64 MB cache and rotates at 7200 rpm – that’s generally the maximum speed you’ll find on common desktop hard drives.

seagate-desktop

At the time of writing, the drive is available in capacities up to 5 TB with the largest drive benefitting from a class-leading 128 MB cache. I’d categorise our selection as a “mid-range” drive.

In the Desktop category, the Seagate Hard Drive competes with Western Digital’s WD Blue product brand, and we’ve included the 1 TB WD Blue WD10EZEX 1 TB WD Blue WD10EZEX  in our test. Like the Seagate drive, it benefits from the same 6 Gb/s SATA connection, 64 MB cache and 7200 rpm spin speed. However, while Seagate’s standard desktop category extends all the way to 5 TB capacity drives, Western Digital caps their Blue range at 1TB. For higher capacities, you’ll need to look at WD Green drives. So let’s do that.

Low Power Desktop Drives

Western Digital’s WD Green hard drives range from 500 GB through to a massive 6 TB. They’ve historically been positioned as “cool and quiet” drives, with lower thermal output than other hard drives – the thinking goes that, over time, additional heat can translate into reduced drive reliability, increases in power consumption and additional noise (your server’s fans have to work harder to extract all of that heat, right?) It’s here that we start to see Western Digital add features into their drives to woo perspective buyers.