Friday, April 24th 2020
Western Digital Spells Out Which Specific HDD Models Use SMR
Western Digital on Thursday (23/04) released an updated statement about the company's stand on SMR (shingled magnetic recording) being used on certain internal hard drives, including certain client-segment WD Red models recommended by the company for NAS applications, without proper disclosure on the product's marketing materials or data-sheets. It's surprising to note that SMR is being used not in some of the higher-capacity models (8 TB or higher) as previously thought, but rather lower-capacity ones, 6 TB or lower, including a 2 TB 3.5-inch drive, and a 1 TB 2.5-incher.
Perhaps SMR is being used in these lower-capacity drives to reduce the number of platters, by cramming in more data per recording surface. As on 22nd April (when the list was internally compiled by Western Digital), there are 9 client-segment hard drives that use SMR, four of which are from the company's WD Red family, two each from the WD Blue 3.5-inch and WD Blue 2.5-inch families; and one from the 2.5-inch WD Black family. Among the WD Red series drives with SMR are the 2 TB WD20EFAX, the 3 TB WD30EFAX, the 4 TB WD40EFAX, and the 6 TB WD60EFAX.
The undisclosed SMR controversy blew up on Western Digital's face last week, when a Blocks & Files report chronicled incidents of several WD Red series HDDs being rejected in RAID volumes during their resilvering process. Over the course, it was learned that even Seagate and Toshiba were selling HDDs with undisclosed SMR, though none marketed as "NAS optimized" ones.
Western Digital earlier this week posted its first response to the controversy, by admitting that some WD Red HDDs use drive-managed SMR (DM-SMR), an internal SMR implementation that's transparent to the host, and pointing NAS users to the company's WD Red Pro, WD Gold or even enterprise-grade Ultrastar product lines. SMR is a physical-layer recording technique that overlaps write tracks over each other to achieve greater data density at the high cost of random write performance, which makes them effectively unfit for serious RAID applications (in turn NAS applications that use some form of internal RAID). Western Digital also provided a general guideline as to which class of its client-segment hard drives are likely to feature SMR.
Source:
Western Digital
Perhaps SMR is being used in these lower-capacity drives to reduce the number of platters, by cramming in more data per recording surface. As on 22nd April (when the list was internally compiled by Western Digital), there are 9 client-segment hard drives that use SMR, four of which are from the company's WD Red family, two each from the WD Blue 3.5-inch and WD Blue 2.5-inch families; and one from the 2.5-inch WD Black family. Among the WD Red series drives with SMR are the 2 TB WD20EFAX, the 3 TB WD30EFAX, the 4 TB WD40EFAX, and the 6 TB WD60EFAX.
Western Digital earlier this week posted its first response to the controversy, by admitting that some WD Red HDDs use drive-managed SMR (DM-SMR), an internal SMR implementation that's transparent to the host, and pointing NAS users to the company's WD Red Pro, WD Gold or even enterprise-grade Ultrastar product lines. SMR is a physical-layer recording technique that overlaps write tracks over each other to achieve greater data density at the high cost of random write performance, which makes them effectively unfit for serious RAID applications (in turn NAS applications that use some form of internal RAID). Western Digital also provided a general guideline as to which class of its client-segment hard drives are likely to feature SMR.
44 Comments on Western Digital Spells Out Which Specific HDD Models Use SMR
Incorrect. SMR drives work perfectly well in RAID. The only problem is mixing SMR and CMR.
Please stop repeating this.
i got 3x WD60EFRX & 1x WD60EFAX
the EFAX was a replacement for a failed EFRX
But I'm not sure why you're asking me that.
We know SMR drives work in NAS and RAID. We know that they have different characteristics than CMR. That's it.
Author of this news is repeating an incorrect information that people start to believe in. That's the problem.
Also, the SMR/CMR issue has been discussed for months now.Hmm. Let's ask Seagate and Toshiba. Where are their statements? :)
Then again, that leaves us with people who use RAID on DIY desktops (or at least added HDDs to an OEM desktop on their own, i.e. not following the OEM recommendations).
Well, DIY group is always vulnerable to this kind of problems. That's why everyone else prefer to pay OEMs to take care of some matters. :)
Still, it's a little unfair that PC websites focus on WD, when the other 2 major HDD makers did almost the exact same thing.
Yes, WD is the only company that marketed consumer SMR drives for NAS - Toshiba and Seagate only use SMR for desktop and archive drives.
That was a mistake and they should fix it. This statement is a temporary solution - they have to correct product datasheets and ideally describe the consequences and how to safely use SMR drives in RAID.
But at that point the overall story given by PC websites becomes incoherent, because:
1) many news authors focus on SMR performance, which obviously affects desktop drives,
2) RAID in a PC doesn't have to be made up from NAS drives.
Server and consumer backup/archive drives were launched in 2014 or maybe even earlier.
Please look it up before you decide to sue me. :)
It may seem like if you just match all CMR or all SMR drive, all will be dandy. But a CMR array rebuild will take hours, maybe a couple days depending on the size of the drive. While a SMR rebuild is going to take weeks. SMR drives are not suited for RAID use because of this.Seagate's statement was that they would never use SMR in a product designed for RAID/NAS use.You think those are the only two options? Either they are using a NAS or they are a DIY doing RAID in a desktop? Sorry, nope.
Professionals aren't all using NAS devices. We're using Servers with RAID, and we're buying these Red drives.No one is saying SMR is new. He/we aren't talking about problems with backup/archive drives, so I don't know why you are even bringing them up. Our problems are with the Red drives. His statement is about mixing SMR drives with CMR drives in a RAID configuration like they are marketed for.
It couldn't be that hard to add an extra row for the technology used...Sooo, they gave you a drive with different specs than the one you had without telling you anything.
A little honesty is all we ask of them, and they can't even do that.
Well, that's how RAID rebuilds are performed. Maybe as SMR drives become more popular, we'll get a more suitable algorithm for rebuilding. SMR is really modern tech after all. But that's something we should demand from controller / server / NAS makers, not from drive manufacturer.
Because in turn buyers expect HDD makers to increase capacity. That's why we have SMR. That's why we'll see other recording methods in next few years. There's no going back to all-CMR universe.
And while I agree with you, this is still a performance aspect.
Something similar could be said about SSD vs CMR HDD. Rebuild takes few times longer. It's just a matter of what you're used to.
Saying that long rebuilds increase a chance of failure is... mathematically true. And not easy to respond to.
If you don't feel comfortable with rebuilds, don't do them. Restore from a backup. It's usually faster anyway.And yet problems with Seagate SMR drives were reported long before WD Red SMR drives were even launched. People wanted to run drives from the Archive lineup in RAID.
Because, as someone already said, RAIDs aren't exclusive to NAS.
Yes, I agree most people run NAS with RAID, so it should be explicitly said what the SMR consequences are. But I expect this information for all SMR drives, from all manufacturers.No offense, but was this meant to impress me or what? It really looks silly. :D
Don't buy consumer Red drives for enterprise applications. There's a product line for that.
Putting it in a product intended for RAID is where the issue comes up.I wouldn't be surprised if the RMA department didn't even know there was a difference between the drives. Or at least not as big of a difference as there really is. It seems WD wasn't even properly informing their own staff that SMR was used in any of their drives.If that happens, then by all means, re-launch them as RAID/NAS drives. But until then, the fact is SMR drives are not suitable for NAS/RAID use, as stated in the original article.It's not new. It's been in use since 2013. That's ancient by computer terms.No, it is absolutely something we should demand from the drive manufacturers. It is their product's performance that is the issue, not the NAS/RAID controllers. The rebuild time is almost always dictated by the speed at which the data can be written to the drives. Introducing an extremely slow drive kills rebuild performance. There isn't some magical algorithm that RAID developers can use where they can rebuild an array by some how not writing data to the new drive. It's just not possible.
On top of that, these drives report to the system the same as a CMR drive. It should be pointed out that there are enterprise SMR drives, but they actually have a method in place to report to the controller/system that they are SMR and the system handled those drive differently. In the case of the WD Red drives, they don't do that, because they are using DM-SMR. So they appear to the system as a CMR drive, and the controller on the drive itself handles all the SMR translation.This statement goes totally against the facts. Yes, SMR can be used to increase capaity. And if we were seeing SMR used in super large capabity Red drives, I'd almost agree with your argument. But WD only used SMR in the lowest capacity Red drives. Explain that! If SMR is about getting higher capacities, why is it only used on the 2, 3, 4, and 6TB sizes and not the 8, 10, 12, 14TB drives. It's 100% not necessary for drives 14TB and smaller, we know this because there are 14TB CMR drives on the market. So your argument doesn't apply.Sure, an SSD array would rebuild significantly faster. But very large capacity SSD arrays are not financially practical for most situations. So we use HDDs. If SSDs were an option, trust me, we'd all be using them. I can come up with tons of unlikely scenarios too if you want, but lets stick to reality, shall we?I have a feeling you've never really had experience with RAID from all your statements. Doing this would require the storage system to be taken offline and not be accessible during the restore. Plus, re-creating the array would require an initialization before the array become redundant, which I'll tell you right now takes a hell of a lot longer than just doing a rebuild. So, no, just restoring from a backup is not usually faster.Yep, and when you run drives outside of their intended purpose, issues happen. Again, you're focussed on your idea that we are complaining about SMR. The issue isn't SMR, it's SMR put in drives specifically marketed for RAID/NAS use.
I was one of those people that took archive drives and ran them in RAID5. I had 3 5TB archive drives. It's exactly how I know the problems that SMR drives cause in RAID. It ran just fine for a couple years, until one of the drives died. I was actually never able to get it to rebuild. I put a replace drive in that was the same model as the others, and when the new drive reached the end of its CMR cache, the controller would see the huge write performance drop, assume the drive was bad and kick it back out of the array. I finally had to give up on it, and I'd never use SMR in RAID again. It's just not worth it.It'd be nice if every manufactuere diclosed it. But it's only required on drives marketed for NAS/RAID use. And that's the distinction here and why WD is in the wrong while the other manufacturers aren't.No, it's meant to inform you that while you might be an armchair quarterback that's obviously never even experienced a RAID array in your life, I do it for a living.
And while there are enterprise grade drives, yes, most small and medium business as well as SOHO users are buying Red drives. They are supposed to be suited for the needs of these companies. Your statement about enterprise drives is ignorant. I mean, should be be putting WD Gold drives in desktops just because they are using at a business? No. The Red drives are not only for home use, no hard drive is. The fact is, even WD says, that the Red drives are for up to 8 Drive RAID arrays for business or home use.
Directly from the WD Red Product page:So it seems the "product line for that" is in fact the WD Red line. :D
Perfect.
IMO, SMR belongs in high capacity Blue drives and the equivalents from other manufacturers, and that's it.
As a stand alone drive, mix the two methods will only cause a slow down on a minor level that most people are completely unaware of. Such a slow down would only be revealed by a drive testing utility.This statement illustrates a misunderstanding of the the technology and how it is employed. SMR is NOT 25% the speed of CMR. It is closer to 94% to 97% that of CMR depending in which part of the platter is being accessed.Fixed that for you.
In a networked application where multiple users are accessing the same single drive, no, you are incorrect.
In a RAID array where you need to rebuild, well, that’s just nonsense — random write performance is essential to a rebuild.You are talking about sequential, not random, performance — no one is disagreeing that SMR offers fine sequential performance.Actually, if they were “mixed mode” drives there wouldn’t be an issue at all... the drives would simply acknowledge the controller and disable SMR. The issue is that the drives aren’t capable of mixed mode, don’t point out SMR in the specs, and don’t offer instructions on how to disable SMR via some firmware utility... Please see the section on data management: en.m.wikipedia.org/wiki/Shingled_magnetic_recording