Wednesday, April 15th 2020
Some Western Digital WD Red HDDs Allegedly Use SMR, A Big Nono for NAS and RAID
Western Digital launched the WD Red line of hard drives and solid state drives specifically for NAS applications. The rigors of NAS involves not just near 24x7 uptime, but also the ability to work in RAID volumes, as most NAS servers ease the process for end users to set up RAID volumes for data redundancy. Data Storage-focused tech publication Blocks & Files alleges that some WD Red HDDs are shipping with shingled magnetic recording (SMR), a physical-layer data recording technique that makes the drive unfit for RAID, and in turn unfit for most serious NAS setups.
SMR is a recording technique that aims to achieve higher data density per platter, by partially overlapping tracks, by taking advantage of write tracks being wider than read tracks. Think of it as trying to cram a little more than one line of text per ruling, in a ruled notepad. The biggest trade-off with cramming in more data using SMR is a heavy loss in random write performance. The controversy of Western Digital shipping SMR WD Red drives came to light when Alan Brown, a network administrator with the UCL Mullard Space Science Laboratory, noticed that a brand new WD Red HDD kept getting kicked out of RAID arrays during resilvering (rebalancing of data with the addition of a new disk to an existing RAID array).
An elaborate investigation and discussion in a Smartmontools thread reveals that both Western Digital and Seagate appear to be shipping HDDs with "DM-SMR" (drive-managed SMR), a feature where the HDD's controller internally performs SMR to increase data density when the physical media is running out of space under CMR (conventional magnetic recording, with conventionally spaced tracks). Think of this as a crude analogue to pseudo-SLC caching employed by modern SSDs. Making matters worse is that DM-SMR drives don't report SMR to host controllers. "Beware of SMR drives in CMR clothing," the thread's title reads. A thread in the user forums of Synology, a prominent NAS manufacturer, recounts a similar horror story.
In our opinion, there's no mitigation for this issue, other than returning your WD Red drives for a refund from your reseller. Western Digital markets WD Red as being optimized for NAS applications. Playing well in RAID volumes forms a big part of that "NAS-readiness." It should be the manufacturer's responsibility to inform customers that the drive uses SMR in some shape or form. DM-SMR counts as one.
Source:
Blocks & Files
SMR is a recording technique that aims to achieve higher data density per platter, by partially overlapping tracks, by taking advantage of write tracks being wider than read tracks. Think of it as trying to cram a little more than one line of text per ruling, in a ruled notepad. The biggest trade-off with cramming in more data using SMR is a heavy loss in random write performance. The controversy of Western Digital shipping SMR WD Red drives came to light when Alan Brown, a network administrator with the UCL Mullard Space Science Laboratory, noticed that a brand new WD Red HDD kept getting kicked out of RAID arrays during resilvering (rebalancing of data with the addition of a new disk to an existing RAID array).
In our opinion, there's no mitigation for this issue, other than returning your WD Red drives for a refund from your reseller. Western Digital markets WD Red as being optimized for NAS applications. Playing well in RAID volumes forms a big part of that "NAS-readiness." It should be the manufacturer's responsibility to inform customers that the drive uses SMR in some shape or form. DM-SMR counts as one.
22 Comments on Some Western Digital WD Red HDDs Allegedly Use SMR, A Big Nono for NAS and RAID
Their RED line of HDD's used to be great but not anymore imho. They really messed up with the pricing of their 14TB models. These cost more than their enterprise Ultrastar line while having worse (or at best equal - the Pro model only) specs. So explain to me why should i buy a 14TB RED drive over and Ultrastar drive when it costs more and has worse specs? The miniscule amount of power saving and small amount of less noise is not worth scrificing years of warranty and reliability. Not to mention that now i might find that the drive does not even support RAID properly and has worse performance.
"I'm so awesome and I used OEM drives in the past"
They just shouldn't be mixed with non-SMR drives in a single RAID matrix.
Which really follows the principle that you should use the same drive models in RAID, because mixing (even without SMR issue) can cause problems.
As in any other situation, if possible, you should not play "power user" and simply follow the compatibility list (as enterprise client would), e.g.:
www.synology.com/en-global/compatibility?search_by=products&model=DS918%2B&category=hdds_no_ssd_trim&filter_brand=Western%20Digital&filter_feature=SMR&p=1
Synology precisely tells you which drives are SMR and gives a fairly decent description of what's going on.
you build the RAID matrix with all same series drives, then after year(s) drive(s) start to deteriorate and you have to replace them
since WD/Seagate won't tell you the drives are not quite the same, you'll get confronted with the situation at hand
Obviously, WD should have included that in the datasheet and openly say not to mix them with PMR. They'll likely fix this after the shitstorm.
Other than that, no big deal. There are different technologies for HDDs and they don't work well together in hardware RAID. We know that. End of story.
The real issue here is like this: what if you have to replace the drives and there are no SMR available in the size you need (or at all)? Because suddenly everyone stopped making them?
That's something to take into consideration.
But what if everyone went SMR and there are no PMR available? :p
For now we're probably covered, since SMR exists in the Ultrastar lineup (maybe it was developed by the ex-Hitachi team).
Both WD and Toshiba announced that PMR and SMR lineups will be developed side by side.
Soon we'll have even more types: MAMR, HAMR. Some RAID compatibility issues could arise.
What can I say... hardware RAID is a problematic and costly idea. Always has been.
Live with the drawbacks or use software RAID (or an appropriate file system) if possible. :)
SMR is not a "disadvantage". It's not cheaper or anything. It's a different tech that makes higher capacities feasible.SMR drives aren't recommended for systems that require fast random writes (NAS, really? :D). The goal is high capacity with decent sequential write.
If you understand what you need, you make concious buying decisions. If you don't, you waste time attacking a company on a gaming forum.
SMR drives have been around for few years: mostly in datacenters but also backup/external drives. How many lawsuits have you noticed? :)
I just noticed another scaremonger got to the SMR wiki page:
en.wikipedia.org/wiki/Shingled_magnetic_recording
This was added today:
"Western Digital, Seagate and Toshiba have begun selling SMR drives without labeling them as such."
Referencing this article:
www.tomshardware.com/news/sneaky-marketing-toshiba-seagate-wd-smr-drives-without-disclosure
which leads to:
blocksandfiles.com/2020/04/15/seagate-2-4-and-8tb-barracuda-and-desktop-hdd-smr/
blocksandfiles.com/2020/04/16/toshiba-desktop-disk-drives-undocumented-shingle-magnetic-recording/
Apparently Toshiba and Seagate started using SMR in desktop HDD. That's actually where SMR performance characteristics may hurt. Why don't you attack those companies? You're a WD hater or what? :D
And SMR does not have a major impact on capacities. Up to 16TB drivers can be manufactured using CMR. Only the bleeding edge capacities (currently 18TB and 20TB that have yet to make to channels) are using SMR. Older dives that are still available and use SMR do so because at some point they needed SMR to hit a certain capacity point. Not so anymore.
And even if your argument is true why use SMR on 2-6TB drives? These capacities absolutely do not require SMR. I can only conclude that it's a cost saving measure to increase margins. There is no other logical reason why a 6TB drive that previously was using CMR for years suddenly needs SMR and why WD "forgot" to inform their buyers of this fact.Customer can't choose a better product if manufacturer does not disclose specs properly. This is false advertising.How many times have manufactures shipped these SMR drives without disclosing that they're SMR?
People can't sue if they don't have all the facts. Now they do and they will sue. Regardless of how many naysayers like you dismiss this issue on gaming forums. Im sure there were people who defended Nvidia too when the whole 3,5GB fiasco started. Or the Apple battery nerfing on older phones. Both of which resulted in class action lawsuits.Um hello? EFAX is a desktop drive, 3,5" and all. You're hiding behind a technicality in case of WD. I don't care that WD uses SMR on NAS drives. I do care however that thay disclose which drives are SMR.
WD isn't gaining anything from this situation. It's just poor quality product documentation.
Because of the compatibility issues, this SMR/PMR should be stated in product description / datasheet (just like it is in WD's enterprise products).Because that's like calling a disadvantage HDD's performance vs SSD.
SMR are slower for random writes, but they make larger drives easier to make and cheaper.
It occurs to me that because of this shitstorm people started to think SMR is somehow inferior to PMR. It's not. It's an advanced tech that most companies worked on recently.
It has it's pros and cons.
Don't treat HDDs as a homogeneous being. They can be very different inside. And it'll only get worse as we move to HAMR (~2023).
Check product compatibility lists and follow the guidance. That's it.Incorrect. SMR increases capacity by design. Assessing this by what products are currently available makes very little sense.
You have to think about capacities we'll want to have few years from now. We have to work on technologies that increase data density. It's a constant process. We can't just add more platters.
There's a very nice and short article by Synology on key differences. Absolutely worth reading.
www.synology.com/en-global/knowledgebase/DSM/tutorial/Storage/PMR_SMR_hard_disk_drivesBecause it means higher data density and less platters/heads.
And that results in faster reads, less latency, less power consumption, less noise and vibration, higher reliability and less manufacturing cost.
WD60EFRX has 5 platters
WD60EFAX has 3 plattersSo where was the aluminium used for WD Red mined? Not in datasheet. Sue them.I'm talking about WD's recommended use scenario, not technical possibilities. They recommend these drives for NAS, where slow random writes are less crucial than in other uses.
How you use it is absolutely your choice.
I've made scrambled eggs on a shovel once. It doesn't mean I can sue Fiskars because it didn't taste good.That's beyond doubt - but not because of performance impact, but the RAID compatibility.
Why ruin their own reputation, just label the drives as what they are, or launch a new series to differentiate them
It's just not stated in datasheet. It's a similar story with other manufacturers.
Datasheet is provided for consumers and they just don't care whether it's PMR or SMR.
It shouldn't matter. We need some abstraction in product specification.
But compatibility is a serious issue and consumers use home NAS boxes with RAID (even if they don't really know what RAID is - it's often automated).
And not every NAS manufacturer provides a proper compatibility list.
So a consumer-friendly specification must somehow state that drives shouldn't be mixed (stating the actual recording technology only covers people who know what it means).
I'm sure datasheets will be updated after this mess.
And BTW: SSD tech isn't mentioned as well.
documents.westerndigital.com/content/dam/doc-library/en_us/assets/public/western-digital/product/internal-drives/wd-blue-ssd/data-sheet-wd-blue-3d-nand-sata-ssd-2879-800092.pdf
AFAIK all of these are TLC.It is definitely a different model. EFRX vs EFAX. It's in the product name.
No, consumers wouldn't know that these drives have different recording tech. Nor should they even know what PMR and SMR mean.
The key information for them should be: not all drives work together in RAID. Because the consumer probably knows his PC uses something called RAID - even if he doesn't know how RAID works.
And the typical generic notice, i.e. buy identical models or ask your device provider. That's it.
Generally speaking though, it's the NAS maker that should tell you what to buy, not the disk manufacturer. And you have to assume a NAS owner doesn't know what RAID is.You can't expect a call center consultant to confirm a spec that isn't availabe in official materials.
But obviously WD response could have been better.
Wake up and smell the coffee notb, WD did a bait and switch on an extremely important technical spec and didn't tell anyone. That is not disputable. Furthermore, when a consumer called to find out, the rep couldn't tell him, his higher ups refused to tell him. WD screwed up. I'm not saying don't ever buy WD again, but it's clear to everyone who isn't a rabid fanboy they screwed up in a big and perplexing way.
You want everyone to waste time learning about magnetic storage? What's the point?Because that's how it works.
Device manufacturer tells you which parts or accessories should be used. That's why NAS makers say which drives are compatible. That's why motherboard makers tell you which CPU and RAM you should use. That's why car makers tell you which fuel should be used.
It's the only realistic way to do this.Then you're not a typical consumer.
The manufacturer of anything should provide documentation that lets normal people use the product. Assuming some basic understanding of what's happening.
It's not for DIY enthusiasts to enjoy.
@notb, try not kissing too much WD ass. It doesn't help anyone, and I don't think this forum should be apologizing for anti-consumer behavior in any way. It's actually kind of disgusting to watch...
The drives are not clearly labelled as been SMR, its a clear bait and switch, adjusting the product code isnt adequate.
SMR does reduce manufacturing costs, we cannot prove if thats their motivation, but it does make them cheaper to make.
SMR does not provide a major increase in capacity, its barely 20%.
SMR kills random writes, the majority of drives out there will be doing some kind of random writes in their lives.
And it's not 20%. In case of the 6TB Red, it's +2/3. SMR model uses 2TB platters, PMR just 1.2TB.Majority so not all. Just buy a drive you need.