4Tb Head-to-Head: Western Digital Green WD40EZRX vs Seagate Desktop ST4000DM000

A universal truth since the beginning of computing has been that you can never get enough storage because you’ll always find something to fill it with. This is true more than ever, with the proliferation of high definition multimedia files, high resolution digital photography, graphically intensive games and even software defined radio. Space demands continue to rise, although hard disk capacity growth has slowed somewhat.

For a long period, we were saddled with only 2Tb and 3Tb drives, and only recently have 4Tb, 5Tb and 6Tb drives emerged. The larger 5Tb and 6Tb drives have an astronomical price-tag to match, and Hitachi even resorts to helium-filling the drives to make it a possibility. They are intended for use by system integrators for high end, data-center applications. It is clear that we are beginning to reach the limits of perpendicular recording technology – the technology that saved us from the 320-500Gb/drive brick-wall. We have been warned not to expect further capacity increases to fall in price as quickly, due to the technical challenges involved in even larger drives.

In all this time, sadly, the ports offered by most motherboards haven’t changed. We see a sum total of about four to eight SATA ports on most consumer motherboards, which effectively limits the number of drives you can have in a machine. Although it is possible to expand this by opting to install a PCI-E SATA controller, many of the cheaper options feature only two ports and are questionable for data integrity and performance, and the higher-end RAID cards cost a lot of money and require fiddling with SFF breakout cables. The only other option is a workstation motherboard, along with the workstation component costs, or to run multiple NASes on a network and live with the power consumption and performance implications.

Luckily, the price of 4Tb drives has now fallen to a point where they are price competitive on a $/Tb basis. Generally, the 4Tb drives have a price tag similar to the 2Tb drives, and slightly (5%) more expensive than the 3Tb drives. For any new system builder looking to maximise the storage available from their SATA ports, it is a reasonable premium to pay. For system upgraders, it gives them an incentive to consolidate the data from multiple drives to free up ports – for more high capacity hard drives or to add auxiliary SSDs.

This makes them quite relevant and interesting to system builders for bulk storage purposes, where the SSDs pick up the load for applications and system drive. Lets take a look at two of the main contenders, the Western Digital Green WD40EZRX and the Seagate Desktop ST4000DM000 which are the two main companies making hard drives, aside from Toshiba which are not as easily obtained.

Western Digital Green WD40EZRX

The first contender is the Western Digital Green WD40EZRX. This is part of their “green” series drives, optimized for cool and quiet operation for desktop applications. It features a SATA III 6Gbit/s connection and a 64Mb buffer. The spindle speed is quoted as “IntelliPower”, but is most likely to be 5400rpm. The number of platters is not specified.

The drive is supplied for OEM installation in a sealed anti-static bag. Unusually, it is plastered with a warranty label on the rear which clearly states that the warranty for the drive is two years.

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The drive looks pretty similar to most recent WD drives, nothing too exciting about that.

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Seagate Desktop ST4000DM000

DSC_6394The second contender is the Seagate Desktop ST4000DM000. This drive is just called a “Desktop HDD”, and features a 64Mb cache and SATA III 6Gbit/s connection. It is a 4-platter, 8-head configuration with a 5900rpm spindle speed (not in the data sheet). The drive itself is specified with a two year warranty, and alarmingly with a reliability spec claiming a 55Tb/year workload limit and 2,400 power on hours!

The drive was also packed in an anti-static bag for OEM integration, but with no large warranty label.


The drive itself looks like most modern Seagate Barracuda Green/LP drives.

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What Happened to the Warranty?

The last time I bought a hard drive, the warranty was a lofty five years for Seagate and three years for WD. The almost co-incidental reduction of warranty between WD and Seagate to just two years seems rather suspicious to me and it’s surprising that I hadn’t heard anything about this before.

When IBM instigated duty cycle limitations on their drives for warranty, that resulted in a backlash. When most drive manufacturers tried to reduce their drive warranties to one year uniformly, that resulted in a backlash which resulted in Seagate offering five years.

But it seems this time, they’re doing it again, apparently to save on costs.

Does this mean that the drives are any less reliable? Possibly, but unlikely. The reason for this is that the drives’ share their mechanics and even their electronics between series – it’s likely that the drives warranted for AV usage and NAS with 24/7 duty cycle and longer warranties are the same drives with slightly different firmware optimization. This slight tweak to the firmware options and warranty are to enforce an artificial market segmentation and cause headaches for those who want to RAID “green” drives. Instead, they will need to buy NAS/Red series drives to have Time-Limited Error Recovery to prevent RAID array breakages in case of any access problems.

It’s a move by drive manufacturers to try and restore profitability to a highly competitive market, and personally, I find it disheartening that they would deliberately “cripple” their products to bare-minimum to compete for price, and sell essentially the same product un-crippled for a premium price, but that’s how the market works. That’s why we now have Black, Blue, Green, Purple, Re, Se, Xe, AV series drives on the WD side, and Desktop, Terascale (formerly Constellation), Surveillance, Video, Enterprise on the Seagate front.

Performance Testing

As part of my drive-commissioning process, I like to validate my drives with my platforms to make sure they can store and retrieve data over the entire surface without corruption. Both drives completed a full random fill and three-pass checksum with no failures. While doing so, I also like to run a few benchmarks, so lets see how well the two drives perform.

Due to the loss of several computers due to various hardware failures, the test platform is an old Foxconn P35AX-S with Intel Q6600 CPU. Onboard Intel SATA II connectors were used to test the drives, which would not affect the test results significantly because the drives were not capable of sustained saturation of the SATA II linkThe computer is running the latest version of Windows 7 with all patches applied.

To compare the drives, the WD result is on the left, with the Seagate result on the right.

Initial SMART Data


Both drives appeared healthy out of the box. Note that CrystalDiskInfo reports the WD Green having a 5400rpm spindle, and the Seagate Desktop having a 5900rpm spindle. At the conclusion of testing, both drives showed no significant changes in the SMART values, which implies no bad sectors were located and the drives were performing nominally.

Windows Explorer

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Once formatted, you can see that both drives feature exactly the same formatted capacity. This is because the capacity points have been standardized, so it is possible to replace a drive in a RAID array with a competitor’s 4Tb drive and it will have the same number of LBAs. What is apparent is the difference between the binary Tb and the weasel Tb and how the difference grows. A 4Tb drive offering 3.63Tb of storage … might make a few people unhappy.

HDTune Sequential Read

Tests were performed using the Full Test option, which resulted in very long test times of ~8-10 hours.


The HDTune sequential read test shows the WD Green peaking at 144.2MB/s and averaging 112.8MB/s. The Seagate Desktop managed quite a bit better with a peak at 176.7MB/s with an average of 141.7MB/s. This is quite a big gap, and is also reflected in the access time, where the Seagate measured 15.7ms, and the Western Digital measured 17.2ms.

What is notable is that the curves are fairly “smooth” which implies that there are many more density zones on these drives, and the density switches quite a few times across the surface. This implies a sort of “desperation” to cram more bits into the drive. The outermost track of the Seagate drive seems to dip down in speed, which is unusual, but may be implying some possible reliability problems towards the outer surface.

Compared to the Toshiba 3Tb “Green” drives, however, it seems we have made a step backward in performance when considering increased areal density (over USB 3.0, they achieved 164.4MB/s maximum and 126.3MB/s average). Comparing to the Toshiba 3Tb 7200rpm desktop drives makes it clear just how much performance is sacrificed in the name of “green” (they achieved a peak of 190.4MB/s and an average of 151.1MB/s). Maybe the Toshiba 4Tb 7200rpm drive should be on your list if performance is your main concern?

HDTune Sequential Write

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A very similar speed trend is seen in the write graphs, although the access time difference narrows somewhat.

HDTune Random Access Read


In the case of a random access read workload, the Seagate bests the WD in virtually every metric, delivering a higher number of I/O operations than the WD and while offering a lower worst case access time.

HDTune Random Access Write


When it comes to writes, the WD wins fairly consistently when it comes to the number of IOPs, but fails pretty badly for consistency at larger blocks with many “long delays” when it comes to making writes. Quite interesting to see the discrepancy here, so it’s not a complete victory for Seagate but pretty close.



Testing with CrystalDiskMark seems to show a narrower gap between the two drives, but the Seagate still bests the WD in all cases except in 4k read where WD wins both for single and 32-queue depth.



Looking at the results from ATTO seems to show the Seagate hitting its full performance by the time we hit 8kB accesses, whereas the WD doesn’t do so until about 16kB accesses. The Seagate bests the WD in pretty much all cases.


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While H2testW is normally used to test USB memory keys, you can also use it to test hard drives. No failures were detected in both cases, but you can see the WD takes almost 10 hours to do a single fill or readback, whereas the Seagate only takes about 8 hours. The performance difference amounts to a two hour difference for a full read! This is why performance might outweigh the claimed energy savings, and energy efficiency isn’t a straightforward thing to measure.

What about the Energy?

When the whole “green drive” idea became fashionable, I was quite dubious of the idea because of the performance hit. It was a good thing in terms of reducing temperature and power supply requirements, however, but it seems that buying a green drive to save money might be a fallacy depending on your workload. In the case where the performance loss of the drive results in a longer run-time, the increased use of energy of the whole computer could easily outweigh the small savings in the drive.

Unfortunately, as I don’t have any dual-rail measurement gear, I couldn’t get power readings from both drives. However, if we take the values from the specification sheets:

Power Consumption (W) Idle   R/W   Sleep
WD 4Tb Green          3.3    4.5   0.4
Seagate Desktop 4Tb   5.0    7.5   0.75

So, it seems that the WD drive is quite a bit lower in power consumption. Lets do some math to calculate the energy required to read the whole drive:

Western Digital

4.5w * 9h 50m 53s / 3600 = 44.31625Wh


7.5w * 7h 51m 25s / 3600 = 58.927 Wh

In this workload, it seems the WD is more energy efficient for the drive alone.

But what’s the difference? It’s 14.61Wh. Since the WD takes 1.991 hours longer to do the workload, if it keeps a computer which consumes just 7.337w on for 1.991hours, then the energy would have broken even.

But that’s the problem, the rest of the computer consumes a lot more than 7.337w. Now can you see why energy efficiency claims are far from straightforward?

Lets take a different case where your drives are idling away for 5 years, 24/7. What’s the difference in energy, and how much does that cost? It’s a bit more simple arithmetic.

(5w – 3.3w) * 365 days  * 5 years * 24 hours / 1000

= 74.46kWh per drive

At a cost of AU$0.28/kWh for electricity, the hit to your wallet is AU$20.85 over the life of the drive. You probably earn more than this per hour. If you had to wait for your slower drive for an hour (over the course of the review, it has been several hours), then you’d have been financially losing. False economy, possibly, although it depends highly on your workload.

In short, I really don’t think the power consumption differences should be a primary factor in your purchasing decision, however, any energy saved is a positive for the environment, but it’s not clear that opting for the slower, more miserly drive is a win overall especially for heavy workloads.


Given the higher expected areal density of the 4Tb drives, one would expect higher performance. While compared to other green drives, it seems to be fairly similar, the performance is poor compared to non-green drives. The performance was quantified, and the Seagate takes a pretty convincing victory, likely because of the increased spindle speed of 5900rpm vs 5400rpm.

About lui_gough

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9 Responses to 4Tb Head-to-Head: Western Digital Green WD40EZRX vs Seagate Desktop ST4000DM000

  1. sparcie says:

    Interesting read! Although I’m not sure if the seagate drive fits in the same category as the WD green drives which in my opinion are basically only really suited as low speed data storage or backup drives.

    I can’t speak for the seagate drives but I have noticed some significant differences between the different classes of WD drives. Green ones tend to have fewer platters, but also have different circuitry for driving the spindle motor (they run at a varying speed). Older models I had the misfortune to use died when put into machines that demanded a decent workload and didn’t last at all well in a RAID. Blue drives are similar in terms of the number of platters but have different firmware that doesn’t vary the spindle speed as much resulting in less wear and tear on the spindle drive circuitry. The drives I recommend for most people are the black drives as they have better performance and reliability in general and can be used in a RAID effectively. They are noticeably heavier as they have more platters than the cheaper drives and have larger caches. They don’t however command the price which the red labeled drives do, which I suspect are as you suggest simply firmware upgraded black drives. The red drives are the only ones I haven’t seen.

    I’d be interested to see how a similar sized black label drive compares to these two, and how much extra performance the higher price buys in the current generation.

    The proper high-end enterprise drives are about the only drives that are quite different from the others. They have a different form factor, are usually SAS, have lower capacity and run at 10K RPM. But that is to be expected as they are pretty much only used in servers.


    • lui_gough says:

      Given that both drives utilize <7200rpm spindles, I tend to "lump" them together as green-era bulk-storage type drives. It's more that Seagate chooses 5900rpm, and WD chooses 5400rpm (give or take a little) generally that causes the difference. It seems to be fairly well proven that Intellipower is merely just a name to hide the fact that it chooses a fixed slow spindle speed. Initially it seemed WD wanted to provide some optimization, but I quote this from their datasheet:

      A fine-tuned balance of spin speed, transfer rate and caching algorithms designed to deliver both significant power savings and solid performance. For each drive model, WD may use a different, invariable RPM.

      To me, this implies it’s a fixed RPM drive – in fact, I don’t hear the pitch of mine vary under different workloads, so it is very likely to be the case. I haven’t yet had a single green drive die on me (out of 6), but some of my friends have.

      Seagate seems to be a little less aggressive with its RPM optimization, and interestingly, Toshiba (ex Hitachi) designs use 5970rpm for that little bit of extra oomph! Of course, nothing beats real 7200rpm spindles (black) or even higher speeds (10k/15k SAS/Enterprise).

      Checking WD’s portfolio:
      – Green = Intellipower (2yr warranty)
      – Red = Intellipower (i.e. Green, with 24/7 certification, TLER and vibration control, 3yr warranty)
      – Purple = Intellipower (i.e. Green, with 24/7 certification, TLER, ATA Streaming, Write-tuned, 3yr warranty)
      – AV = Intellipower (i.e. Green, with 24/7 certification, ATA Streaming, Wear levelling, 3yr warranty)

      – Black = 7200rpm (5yr warranty)
      – Blue = 7200rpm, although there are very few models, tops out at 1Tb (2yr warranty)
      – Se = 7200rpm (i.e. Black with TLER, 24/7 certified, extended testing, 180Tb/yr workload, 5yr warranty)
      – Re = 7200rpm (i.e. 512 byte sector version of Black, but with SAS, TLER, 24/7 certified, extended testing, 1.2m-1.4m hrs MTBF, 550Tb/yr workload, 5yr warranty)

      – Velociraptor = 10,000rpm (Advanced Format, 2.5/3.5″ form factor, tops out at 1Tb, SATA, 1.4m hrs MTBF, 5yr warranty)
      – Xe = 10,000rpm (i.e. 512 byte SAS version of Velociraptor, TLER, tops out at 900Gb, 2.5″/3.5″ form factors, Unlimited workload, 2m hrs MTBF, 5yr warranty)

      Note how I’ve bundled drives which are likely to be based on the same platform with minor changes, it’s probably all down to firmware and possibly even factory testing. Minor changes to the PCB to add vibration sensors too, possibly. Lets take a quick look at Seagate as well:
      – Desktop HDD = 5900rpm (2400h reliability, 2yr warranty)
      – NAS HDD = 5900rpm (8760h reliability, 3yr warranty, TLER, twice as many load/unload cycles, 1m hrs MTBF)
      – Terascale HDD = 5900rpm (8760h reliability, 3yr warranty, 800k hrs MTBF)
      – Surveillance HDD = 5900rpm (8760h reliability, 3yr warranty, tuned for high write, rotational velocity sensor)
      – Video HDD = 5900rpm (8760h reliabiliy, 3yr warranty, qualified to 75 degrees)

      – Constellation CS = 7200rpm (8760h reliability, 3yr warranty, 800k hr MTBF)
      – SV35 = 7200rpm (8760h reliability, 3yr warranty, tuned for high write)
      – Enterprise Capacity HDD = 7200rpm (8760h reliability, 5 yr warranty, 512 byte sectors, SAS, Humidity Sensor, Super Parity, 1.4m hrs MTBF, 10x lower unrecoverable read errors)

      – Enterprise Performance 10k = 10,000rpm (5yr warranty, SAS, 512 byte sectors, 100x lower unrecoverable read errors)

      – Enterprise Performance 15k = 15,000rpm (5yr warranty, SAS, 512 byte sectors, 100x lower unrecoverable read errors)

      I think it’s much clearer the similarity between the product models which would imply they use the same platform with minor changes. However, if you look at the price and the differences, it’s clear that they’re trying to give you reasons to upgrade to more expensive models by removing functionality from their most basic drives. It was much easier in the earlier days – it was, at most, choose a brand, spindle speed and a cache buffer size!

      – Gough

  2. sparcie says:

    Ah perhaps WD changed it’s tune! A few years ago when I was still in IT support we had put a number of green drives in a Netgear NAS in a RAID configuration. The drives lasted a few months at best before a number of them died at once. We removed and checked them out physically and found the spindle drive circuitry had discoloured and it seemed the drives were no longer spinning. The NAS had reasonable ventilation so we investigated and found that WD had the drives spin slower during idle times then accelerate when in use. Our theory was that put undue strain on the spindle drive circuitry and the RAID may have caused the drives to spin up and down a lot. We installed black drives and the Array worked well and no more drives came back for warranty.

    I’ve typically found the modern hard disks quiet enough that it is difficult if not impossible to notice the sound of the spindle motor, especially over the noise of the rest of a machine. Only the really fast 10K and 15K drives are easily heard.

    The drives I’ve seen the most are the green and black ones, and they do have a noticeable weight difference. I noticed in the casting for the body of the drives on the black ones have room for more spindles, that coupled with the extra weight made me think they have extra spindles. (that is comparing two drives of the same capacity) I do agree that there are marked similarities between many of the drives, but as you say there are a few different classes which are different from each other. The trick is picking the best value drive from the bunch.

    I recommend the black drives mostly because they continue to have the 5 year warranty and I have seen they have a better track record than the green drives (I used to handle a lot of WD drives!) If you don’t need the capacity and don’t want the expense the blue drives reliability is also quite reasonable.


  3. Pingback: Review: Seagate Archive 8Tb 3.5″ Internal Hard Drive | Gough's Tech Zone

  4. Martin Mark says:

    WD40EZRX just died after 174 day use

    • Percy says:

      Two WD40EZRX died after 2 months , terrible.

      • lui_gough says:

        Unlucky it seems. Such issues are likely because of poor handling of the shipment of drives – maybe you bought yours online and your courier wasn’t too friendly with the package, or you bought it from a shop where the shipping pallet or container was once dropped.

        For the record, I now have eight Seagate ST400DM000 of which one has a high-fly writes counter increment issue but all are still functioning. The two WD WD40EZRX are also still perfectly functioning, both in 24/7 style roles.

        – Gough

  5. Punk says:

    Fantastic write-up! Amazing that the cheaper drive wins out, must be an expensive label!

  6. Chris says:

    Thank you for the in-dept testing. As I am new to WD drives (Maxtor, Samsung & Seagate before) I am very interested in such test, especially because I am experiencing some weird stuff going on on my WD40EZRZ as well.
    Does ANYBODY have the same problem that it takes the WD40EZRZ about 120 secs to get out of sleep? It doent freeze my PC but is very annoying to wait for 2 mins. Never had this on any HDD before (and I am into IT for over 20 years). And yes, I have IntelliPark diabled…..
    Anyone maybe? Any help yould be very appreciated!

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