Western Digital Fesses Up: Some Red HDDs Use Slow SMR Tech Without Disclosure


Level 29
Top Poster
Sep 13, 2018
Very good. The fact that Western Digital reversed itself with this disclosure indicates a tacit acknowledgement that this is simply the right thing to do. I forgive 'em. 😘

From a consumer standpoint, I'd want to know up front. And now some of us know what SMR in general is and what to look for when shopping for hard drives.


Level 2
Apr 20, 2020
Without bad publicity, WD would not change a thing. Now I hope they clarify their communication about SMR, and best case this publicity leads to innovation to improve SMR performance for future drives. When WD accomplishes that, they are encouraged to communicate and celebrate that of course ;)

Wow, that was quick.

Very good. The fact that Western Digital reversed itself with this disclosure indicates a tacit acknowledgement that this is simply the right thing to do. I forgive 'em.

I agree with plat1098.
It sounds like WD agrees that their communication about the new WD Red drives was inadequate. We asked for clarity, and WD provides it now. Respect.

Trust is built in drops and lost in buckets, so I'll make sure to doublecheck HDD specs before I buy something. As usual :geek: :coffee:


Level 16
Top Poster
Oct 13, 2019
Just digging this up now that more data is available: WD Red SMR Drive Compatibility with ZFS - iXsystems, Inc. - Enterprise Storage & Servers

  1. At least one of the WD Red DM-SMR models (the 4TB WD40EFAX with firmware rev 82.00A82) does have a ZFS compatibility issue which can cause it to enter a faulty state under heavy write loads, including resilvering. This was confirmed in our labs this week during testing, causing this drive model to be disqualified from our products. We expect that the other WD Red DM-SMR drives with the same firmware will have the same issue, but testing is still ongoing to validate that assumption.
  2. In the faulty state, the WD Red DM-SMR drive returns IDNF errors, becomes unusable, and is treated as a drive failure by ZFS. In this state, data on that drive can be lost. Data within a vdev or pool can be lost if multiple drives fail.

Sounds like the noise about SMR performance is, as some argue, not a big issue, but the real problem is that a certain firmware version has a reproducible bug that results in the drive returning IO errors during ZFS resilver (RAID rebuild) operations, and that can cause a complete loss of the pool if you do not have an additional redundancy drive.

That is a serious issue. A lot of people use RAID-Z1 (RAID5 equivalent) or RAID-Z2, and the idea that you can lose a 20TB array because of a firmware bug in the drive is frightening.


Level 29
Top Poster
Sep 13, 2018
Oh wow, OK. It's not over. Western Digital learns a tough lesson, it seems.



Level 1
Mar 29, 2020
AS LONG AS the drive makers publish the essential performance and warranty specs (which they do), why does it matter?

I would agree but, those are marketed as NAS drives. WD reds have been used for a very long time in NAS systems and suddenly they give problems in those builds because underneath technology has been changed without notice.
I've put up my first backup server two weeks ago. I was going for a bunch of WD reds but fortunately I've been diligent doing my home work and went with Ironwolfes instead. I was about to make my company spend a few hundred euros on devices that wouldn't have fitted the zfs raid. That's not good.

Edit: oops, that was an old post. My bad.


Staff Member
Malware Hunter
Jul 27, 2015
Law firm Hattis & Lukacs has filed an amendment to its class-action lawsuit against Western Digital for including SMR technology in its WD Red line of NAS drives. The amendment adds five more named plaintiffs from five new states, and it includes significant additional technical detail.

If you aren't up to date on the SMR saga, this is one article in an ongoing series. The short version: SMR—Shingled Magnetic Recording—is a relatively new hard drive recording technology that allows higher data densities. It does so by laying down overlapping tracks—like shingles on a roof—with a write head that's wider than the read head. Unfortunately, this technology makes rewriting existing disk sectors agonizingly slow in many cases—rewriting a single 4KiB sector will generally mean needing to both read and rewrite an entire 256MiB zone. The original American class-action suit (there's a Canadian one as well) had a single named plaintiff, Wisconsin's Nicholas Malone. The amendment features five new plaintiffs, each from a different state, and tells each plaintiff's story in detail.


Level 1
Nov 6, 2019
WD has a mediocre legal department, like most! Civil lawsuits in the US only require a "preponderance" of evidence and
a unanimous jury is not needed. Parties tend to settle out of court. If I am not mistaken, the rub here is that the CMR/SMR didn't
matter before due to performance not being an issue UNTIL SMR came out. This has nothing to do with WD not being a charity. It
doesn't exempt them from tort law. In fact, charities are even lazier legally.


Level 44
Top Poster
Nov 10, 2017
WD's announcement outlines a new series of WD Red Plus drives that come with the standard CMR technology, but in the same 2 to 6TB capacity points as the slower SMR drives. WD positions the new Red Plus drives for its customers with more demanding needs, particularly in the SOHO and SMB segment, that need better performance with ZFS RAID arrays.

WD will continue shipping the 2 to 6TB WD Red drives with DM-SMR (Drive-Managed SMR) for less-demanding SOHO users, with the existing CMR WD Red drives being moved to the WD Red Plus line to create a split product stack. The WD Red Pro line remains unchanged with CMR drives.

WD has started listing its existing hard drives with SMR technology in marketing materials, and retailers have updated product listings. For some impacted customers, the company is also replacing SMR drives with faster CMS models. Still, WD will have to be clear with the new drive positioning to avoid confusion among less tech-savvy customers that could seek out the WD Red family as a value alternative while not fully understanding SMR's impact on performance.


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