Western Digital Black 6TB HDD Review


Author: AkG
Date: December 26, 2015
Product Name: Black 6TB
Part Number: WD6001FZWX
Warranty: 5 Years


It may seem counter intuitive to enthusiasts who have migrated entirely over to SSDs, but standard spindle-based media isn’t on its way out the door anytime soon. Instead the main goals and design priorities of traditional hard drives have simply changed along with the changing market.

Western Digital has effectively evolved in the last few years from a company that has focused upon trying to deliver the absolute fastest drives possible (an achievement now reserved to SSDs) to one which offers a broad range of high capacity storage solutions. Lineups like the Blue and Green series have been consolidated into a “mainstream” product offering under the Blue designation that hopes to combine extreme capacities alongside affordable prices and good performance. There’s also the Red, Red Pro and RE series which cater to NAS environments and the surveillance system friendly Purples. Meanwhile, the famous Black drives continue to strive towards a combination of leading edge (for spindle-based storage) throughput and massive storage space at a slightly higher price point and without the energy-savings technologies of the Blues.

In the past a Black series drive had to be capable at handling files of all sizes and do so in every given situation. In other words, they had to be good at dealing with the Operating System’s demands, and short to mid-term storage needs. Today the same does not hold true since in many cases Hybrid Drives and SSDs have taken over the ‘OS Drive’ duties for more and more users, and the classic hard drive has been relegated more to secondary storage duties items such as games and pure data. This is true for both system integrators and DIY builders as setting up a dual storage system is now easier than ever.

There is still however a relatively large audience who can’t justify the capacity limitations of even today’s SSDs in relation to what’s available or much less money on the HDD side of the fence. Performance be damned. Western Digital also needed to insure the Black’s capabilities still satisfied these folks’ needs as well. That’s a pretty tall order.

Instead of being loud, fast and essentially a perfect alternative to the 10,000RPM drives of yesteryear, the newer generations of Blacks make less noise, used less power, created less heat, and had firmware tuned more towards sequential read/write performance instead of raw IOP/s performance.

In plain English this all means the newer Black series drives still offer more overall performance than many of the other series under WD’s wings due to their larger cache buffer, higher 7200RPM rotational speed and other advanced features. However, the Reds, Blues, Purples and more datacenter-focused solutions all have various strengths that are tailor-made for their particular market. For example, the RE-series has extended MTBF, enhanced data recovery abilities and durability, all elements that will make datacenters happy but are completely unnecessary in a home environment.

The newer Black 6TB follows down the new path blazed by the 4TB version some time ago, and takes Western Digital’s high performance mass market series further and further into the future. As with the 4TB model, the 6TB Black offers extremely good capacity, peak performance of well over 200MB/s, and accomplishes both without excess noise.

On just a cursory glance these elements along would make anyone wonder why they should purchase the significantly more expensive Black 6TB over the older 4TB edition…..besides getting 50% more storage space of course. After all, both models offer massive amounts of capacity, make use of a dual core controller, come with a 5-year warranty, use the same 3.5” form-factor, and even look identical.

Furthermore, neither makes used of exotic builds like sealing the chassis and filling the inside with helium, nor do they make use of SMR (shingled magnetic recording) or HAMR (heat-assisted magnetic recording) to boost platter densities. They do not even use onboard NAND to boost performance. Instead both use classical PMR (Perpendicular Magnetic Recording) technology and only have a relatively small amount of onboard RAM cache to boost performance.

The answer to this is simple: the devil is in the details. The last generation 4TB made use of four 1TB platters and eight read/write heads (one per side, per platter). The 6TB does not use 1TB platters but instead boosts densities by 20% to 1.2TB. This in addition to having ten read/write heads means overall performance should be noticeably better than the 6TB Black’s predecessor – which was no slouch in the speed department. In other words, the new 6TB Black promises to be even faster, stay faster longer and generally be more efficient than any Black model previously released.

In order to take advantage of this increased performance potential Western Digital has also upgraded numerous key core components. The first and most obvious is the RAM Cache has been boosted to 128MB from 64MB. More importantly thanks to improved Dynamic Cache Technology the underlying caching algorithms are even more prescient at guessing what will be requested next, and moving the data off the relatively slow platters and on to the RAM cache before the request is made. In theory this too should further boost overall throughput well beyond what the last generation was capable of.

The dual core controller is also newer and more effective and while it still is ‘only’ a dual core design, its abilities have drastically been improved since the 4TB Black days. Interestingly enough, the controller is now LSI branded rather than being a Marvell-based SoC. This new more powerful design should push the newer generation HDD into different territory, especially during deeper queue depth IO request scenarios.

In addition to these changes there are two more that are quite interesting and noteworthy. Firstly, instead of one flash chip for the firmware, Western Digital has included seven. Obviously the firmware has become larger and a certain amount of redundancy is now being included.

In addition, Western Digital now includes three shock sensors. These shock sensors were included on the previous Blacks but are now more sensitive and capable. What these do is allow the drive to sense in real time any potential damaging vibrations or shocks, and adjust the height of the arms so that ‘cow belling’ (the heads slamming into the platters) does not occur.

Mix in a five-year warranty, that still includes free advanced exchange RMA options, and an online average price of $280 (or 5 cents per GB) and what we have is a complete package that boasts a cost that doesn’t seem all that unreasonable given the abilities this new Black edition has to offer.

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