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"5400 RPM class" HDD spins at 7200 RPM

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The WD100EFAX "5400 RPM class" drive in the following review actually spins at 7200 RPM.

A new twist to IntelliPower?
The WD141KFGX "7200 RPM class" drive in the following review has a strange HD Tune access time graph.

The spread in the access time data points is more like what one would expect from a 4000 - 5000 RPM drive. AFAICS, the only other explanation for a 7200 RPM drive with such a graph would be if it required two revolutions to read the target sector, which would then imply that it was faulty??? However, the performance is genuinely "7200 RPM class", as advertised, so there has to be some other explanation.

BTW, the 14TB drive features Two Dimensional Recording (TDR). This is evidenced by the two read channels running between the MCU and HDA connector on the PCB.

Tip: How to identify the Read Channel test points:

Could I ask the reviewers if they would consider posting detailed, high resolution photos (or CCD scans - better) of HDD PCBs in future articles? There are many things that a trained eye can discern from a PCB and its components which are not present in the official literature (most of which is just marketing pap). For example, many air HDDs have a barometric pressure sensor on the PCB. This feature is not mentioned in any tech docs.

Another useful feature of HD Tune is that it can tell us the number of heads.

How to determine number of heads using HD Tune:

Edited by fzabkar
extra info

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Good stuff, thanks for posting, Franc.

I thought the tested access time on the drives were really strange as well, but I ran some tests doing a frequency analysis.


With no other major sources of sound, I did a frequency sweep and there certainly is a peak around 120Hz for both the WD Red and WD Red Pro 14TB drives.

WD Red 14TB:


WD Red Pro 14TB:


That more or less correspond to 7,200RPM. Also, the power consumption of both drives is 14TB, same as the IronWolf 12 and 14TB:


What do you think?

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So I was wrong about the 14TB model. It definitely spins at 7200 RPM. I didn't think to compare the power consumption, but there should be a slight difference if the number of platters isn't the same.

Both drives are in fact rebadged HGST models, perhaps with modified features. HGST's product manual specifies 8 discs and 16 heads for the 14TB model, but your review claims that it has 9 platters ???



Edited by fzabkar

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Sorry, I was confused. I now see that you are comparing the 14TB drives in these reviews:

https://aphnetworks.com/reviews/western-digital-red-wd140effx-14tb/2 (WD Red 14TB, 5400 RPM class)
https://aphnetworks.com/reviews/western-digital-red-pro-wd141kfgx-14tb/2 (WD Red Pro 14TB, 7200 RPM class)

This is the info from the labels:


WD Red Pro 14TB - 7200 RPM class

Model: WD141KFGX-68FH9N0
NX HA710
R/N: US7SAP140
P/N: 2W10505
WWN: 5000CCA264D62B9D

WD Red 14TB - 5400 RPM class

Model: WD140EFFX-68VBXN0
NX HA500
R/N: US7SAP140
P/N: 2W10504
WWN: 5000CCA264D1C5F5


It would appear that "NX HA710" and "NX HA500" indicate the class, among other things ("7" = 7200, "5" = 5400).

The WWN (World Wide Name) indicates that the drive is a native HGST. The Organisationally Unique Identifier (OUI), 000CCAh, was assigned to HGST. Native WD models have an OUI of 0014EEh.


The R/N is a "Regulatory Number". For both models this is "US7SAP140" which corresponds to the 14TB SATA version of the Ultrastar DC HC530:


The applicable HGST model numbers are WUH721414ALE6xx (512e) and WUH721414ALN6xx (4Kn).

Hard disk drive specifications Ultrastar DC HC530 3.5 inch Serial ATA hard disk drive Models: WUH721414ALE6L4  WUH721414ALE6L1:


It would appear that the two WD models are essentially the same drive, at least physically.

Native WD models have an R/N which is reflected in the part number of the PCB. That is, a WD drive with PCB p/n of 2060-771234 would usually have an R/N of 771234. The same R/N could apply to several capacities within the same family, if they use the same PCB. However, in HGST's case, the R/N appears to reflect both the capacity and family, not just the family alone.

The two PCBs look similar at a glance (hi-res images would help a lot). Both have three differential pairs of traces running between the MCU and the HDA connector. One pair is the write channel, while the other two pairs are read channels. This implies that both PCBs support TDR (Two Dimensional recording). However, HGST's manual does not mention this.

The HC530 datasheet does mention TDMR (two-dimensional magnetic recording):


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Thanks. Looks like I have made a mistake, and I really appreciate the correction. I've also updated all the reviews to point out the WD Red 14TB is indeed a 7,200RPM drive. It's interesting if you look at WD's specs sheets, it shows the WD Red actually uses a little more power than the Pro version (!), but this explains it all.

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These appear to be 7200 RPM drives as well:


The HD Tune access time graph is 8msec wide.

The drives appear to be native HGST models. This time there is a single read channel, so no TMDR.

Contrary to what is stated in the review, the PCB does appear to have two shock sensors and op amps for rotational vibration sensing. A better photo would help to confirm this. I guess it is possible for the firmware to have been programmed to ignore these sensors (to differentiate this model from the "Pro"), but it would be a cynical thing to do.

This is the sort of obfuscation that WD engages in:


The WD60EFRX specifies its RPM as "Rotational speed (RPM): IntelliPower". I suspect that disc tools such as CrystalDiskInfo would report an RPM of 0. This is what "IntelliPower" models usually report via the ATA Identify Device command.

In fact the HD Tune access time graph is 11msec wide, which is what we would expect from a 5400 RPM model (as stated in the review).


Edited by fzabkar
extra info

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I usually take some closer up photos for my own reference, so here it is one that I took in 2017:


It looks like it does have a shock sensor (top right). I'm using the drives in a NAS right now, so not going to take them out for more photos haha. I agree it's strange for them to do that, probably to get people to upgrade to the Pro models.


120Hz as well, held up to my QNAP NAS.

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I have written up an article/tutorial on these sensors. Some laptop drives have tri-axis accelerometers.

Hard drive shock sensors:


Another thing which many people look for, and which is missing from aphnetworks reviews, is whether a drive is a CMR or SMR model. WD likes to obfuscate this point as well

This is WD's specification page for the WD141KFGX:

… and product brief:


They both mention "CMR Recording Technology".

The datasheet for the Ultrastar DC HC530 states that it is "based on conventional magnetic recording (CMR) technology for drop-in simplicity in enterprise and cloud data centers".

There have been a lot of customer complaints regarding this SMR/CMR obfuscation, so WD has finally come clean:



AFAICT, the WD141KFGX and  Ultrastar DC HC530 are essentially the same drive. ICBW, though. However, there are differences in the specs.

The WD141KFGX  has an MTBF of 1 million hours whereas the HGST models are rated for 2.5 million.

The WD141KFGX  has an  error rate (non-recoverable bits read) of less than 10 bits in I0^14, whereas the HGST's error rate is 1 in 10^15. That's a 100x difference. The spec for the WD141KFGX  looks wrong.

The WD141KFGX  has a maximum data transfer rate of 255 MB/s. The datasheet defines MB/s as follows:

"As used for transfer rate or interface, megabyte per second (MB/s) = one million bytes per second".

The maximum sustained transfer rate for the Ultrastar DC HC530 (14TB) is 255 MiB/s or 267 MB/s (typical).

Once again there is a discrepancy, but HD Tune confirms that the max rate for the WD141KFGX is 267 MB/s.

Edited by fzabkar
extra info

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Actually, all our reviews specify whether they are CMR or SMR. You can see that in Page 2, Paragraph 2 of every review. They all read the same.


With these high-density platters using conventional magnetic recording technology as opposed to performance-penalizing technologies like shingled magnetic recording, this should translate to great performance in our benchmarks.


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Sorry, I only searched for CMR and SMR.


More observations ...

Two features which are touted for the WD141KFGX are 3D Active BalanceTM Plus and NASware 3.0.

"Our exclusive advanced firmware technology, NASware 3.0 enables seamless integration, robust data protection and optimal performance for NAS systems operating under heavy demand."

NASware is firmware based, so the question I would be asking is, if native HGST and native WD drives have different firmware architectures (which I have verified by dumping and parsing the ROMs of these new models), and if the WD141KFGX is a rebadged HGST HC530 (ie they both have HGST firmware architecture) , then how has this WD feature been "seamlessly integrated" into HGST firmware?

This news item would suggest that NASware  3.0 was released in 2014 or earlier:


So after 5 or 6 years, NASware is still at 3.0?

As for 3D Active BalanceTM Plus, I couldn’t find what I was looking for on WD’s web site, but I found the following review:


According to WD …

"3D Active Balance Plus - Our enhanced dual-plane balance control technology significantly improves the overall drive performance and reliability. Hard drives that are not properly balanced may cause excessive vibration and noise in a multi-drive system, reduce the hard drive life span, and degrade the performance over time."

According to the reviewer …

"I used WD’s blurb for that last one, but as a translation - this is HUGE. There is a system of movable counterbalances installed in the spindle motor hub assembly. These weights are free to shift, and with the drive at speed, those parts will settle in positions which act to actively counter vibrations. WD had a video showing this, but I prefer a simpler automotive-related analogy, which I will present in the form of this video: Western Digital’s system is much more complex than the simple example above, as it functions both axially and radially. This is the equivalent to obtaining a continuous and automatic dynamic balance of the wheels on your car. While that would give you a smooth ride, WD’s implementation gives you a silent and non-vibrating drive. This works so well that all I can hear from a running Red is the faintest sound of air turbulence across the spinning platters."

I find it strange that there is no mention of this dynamic balancing technology in the HGST datasheet.

In fact my observations on WD's NAS models of that time (Jan 2015) raised more questions regarding WD's marketing approach:


Edited by fzabkar
correction and extra info

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Here is yet another WD thread:


This time the user is asking whether his model incorporates "data loss protection" in the event of power loss. Once again I found inconsistencies between the claims and the actual components on the PCB.

BTW, this PCB has a barometric pressure sensor at location U7 (upper middle):



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I'm kind of confused now - why did WD give such confusing ratings and why not just advertise the true RPMs?

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2 hours ago, TL6MT said:

I'm kind of confused now - why did WD give such confusing ratings and why not just advertise the true RPMs?

A manufacturer could design and build one physical product and then doctor its firmware to artificially create two performance classes. That would result in economies of scale and minimise the cost of development.

I first became aware that something was not right with WD's "IntelliPower" models when it was claimed that these drives could vary their speed from 5400 RPM to 7200 RPM according to workload. I don't know where these false claims originated, but WD's own staff were making these same statements in WD's own forum. I know that HDD manufacturers typically provide promotional packs for their resellers, so I'm wondering whether retailers such as Newegg, or perhaps reviewers of the products, received such disinformation via this channel.

Edited by fzabkar

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