Western Digital – WD100EFAX or WD101EFAX


Running low on NAS disc space? You might stumble upon two different variations of the Western Digital WD Red 10TB and wonder which one to choose.


The first thing you might notice is the lower price of the WD101EFAX, at least here in Europe. But looking at the specifications below, you quickly notice some odd trade-offs. The WD101EFAX is louder and consumes more energy:

Interface Transfer Rate up to210 MB/s215 MB/s196 MB/s
Average power requirements (W) – Read/Write / Idle5.7 / 2.88.4 / 4.66.3 / 2.9
Acoustics (dBA)
/ Seek (average)
20 / 2934 / 3820 / 29
Source: Product Brief: WD Red NAS Hard Drives

I also added the 12TB variation for a better context. But what is the actual difference between those two models?

Helium or Air-Filled?

Western Digital doesn’t communicate the difference between the two hard drives and a quick online research doesn’t reveal much either. However, a German message board points to an article about the Western Digital Ultrastar DC HC330. The big feature of that hard drive was the usage of air compared to helium. The trade-off? More energy consumption and a higher operating noise.

Users on r/DataHoarder reached similar conclusions , a quick search on this subreddit also reveals that many dislike the newer model for its loudness and temperature. Some users also pointed out that Western Digital (and other manufacturers) quite recently conceiving product changes, regarding the usage of SMR over CMR in some drives.

One argument popping up very often concerns the reliability of helium-filled hard drives. But according to backblaze.com the Annualized Failure Rate (AFR) seems to be the same compared to air-filled hard drives.

Which one to buy?

Looking at the comments on Reddit, users seem to be rather unhappy with the WD101EFAX. Comparing the prices of those two hard drives it gets even worse. The old WD100EFAX was basically never sold much bellow the 300 Euro mark and usually more around 330 (according to a price comparing website). The WD101EFAX is currently sold at around 300 and was never cheaper than 290. This means you save 10-40 Euro to get a hard drive which is 9 dB(A) louder and consumes 2,7W more power, its also only 5MB/s faster.

However, whilst writing this article the prices for the WD100EFAX are already at around 350 Euro. Plus I wouldn’t trust retailers to differentiate strictly between the two models. But hey, at least my order was canceled after they discovered it.

12TB alternative

Taking a look back at the table above, you might notice a certain 12TB hard drive. If you’re using Synology’s Hybrid RAID (SHR) you potentially loose 2TB, but the WD120EFAX is currently sold for roughly 350 Euro, landing in the ballpark of the old 10TB. Of course, it’s using 0.6W more compared to the WD100EFAX and it’s 14 MB/s slower. But comparing the specs to the current WD101EFAX you might end up with something better, especially if you’re used to the WD100EFAX.

Western Digital Red 12TB

But I do hope that this topic will get more publicity, including detailed comparison tests. What’s even worse, it also shakes my trust in Western Digital. Selling a hard disc with noticeable worse specifications at an almost unnoticeable price difference without even communicating whats changed brings to mind the recent SMR/CMR issue. Which is a pity, since I have a very good track record with Western Digital hard drives, so I do hope that this kind of product changes will be communicated more open in the future. This way I can decide for myself to stock up on the old model or wait for the newer one to get cheaper (and live with the downsides).

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3 thoughts on “Western Digital – WD100EFAX or WD101EFAX”

  1. Interesting article… I have a WD My Cloud Ultra EX2 with two 10TB drives – one of which has failed. It is a WD Red WD100EFAX 10 T. Finding an identical drive for replacement is proving tough. Would it matter if I used another manufacturers’ 10TB SATA drive instead? (without looking again, I’m assuming at it’s a SATA drive). I assume that all SATA drives would fit on the pcb board and be compatible – actually, I guess that’s a question!

    1. Thanks! And I would assume other drives with the same capacity should work? But it depends on the setup and used RAID etc. so maybe check with WD directly to figure out the best replacements.

  2. Hi Christof,

    the same like you I had an extremely good track record with WD, but in the last time I was more than fooled by WD.

    I had started with buying some WD products and because of the extremely helpful and easy-going support – failing products where immediately replaced where the support couldn’t fix it – I bought more and more WD products with more and more capacity at a higher price.
    We had several USB and SSD drives, MyBooks, MyBook Duo’s and WD Red drives for NAS, all in all around 100 Terrabyte.

    However, service and its response times as well as transparency went down and appears to be crushed ultimately.

    En detail,
    – first I got a replacement for my good CMR discs with SMR without further notice. When complaining, WD told me they would be of the same quality which turned out to be untrue.
    – second, when replacing 4TB WD Red discs with 10 TB WD Red Plus discs in my Synology NAS (which were listed on Synology’s compatibility list), the NAS turned from a pleasantly silent working device into a loud and disturbing vacuum cleaner, disturbing considerably all in the room. At the same time the temperature climbed up with 10 degree celsius.
    Another WD Red Disc from another source with the same capacity of 10TB turned out to be at the normal temperature 10 degree less.
    – third two new WD RED disc failed, one immediately and the other after two months. They were old models with older production dates that WD obviously wanted still to distribute although negative news were available in expert forums.
    – Next, the support does not replace products in time, not even receipt can be confirmed after two weeks, leaving us with holes in NAS systems and instability.

    All in all, transparency what you buy is not anymore there. What you order may not be what you get at WD.

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