> “In a typical small business/home NAS environment, workloads tend to be bursty in nature, leaving sufficient idle time for garbage collection and other maintenance operations.”
Only up until the array needs to be rebuilt (eg replacing a drive). At which point the workload is the literal opposite of "bursty with idle time". :(
My understanding is that it removes the ability to do random writes, since you'll disturb the nearby tracks. Like drawing pen thickness rings with a sharpie by overlapping them.
Instead you read data in, modify it, then write it out, like an extreme version of updating a byte in a cache line.
Your ability to read is more precise, so you have no trouble reading data laid out in this way.
Large contiguous writes are also pretty quick. I've owned one, and if you stick to large files it's fine. Pathological workloads like creating millions of small files can take days.
I'm not sure if drives do this, but it's theoretically possible to linearize a random write workload, with the disadvantage that when you come to read the data, a sequential read becomes a random read.
Typically stuff you write randomly (small files, databases) one tends to read randomly, so it's usually worth linearizing writes.
The only case where you are at a performance disadvantage is when you did random writes followed by more than one linear read.
Things like LogFS do this, as do most SSD's. I'm pretty surprised modern HD's don't do it internally too.
> it's theoretically possible to linearize a random write workload
In fact OSes have been doing this for years now. Over a decade. There is a drawback however. To make this work you need to buffer your writes in a cache, typically in volatile memory, so they can be sorted before being written to the drive. The larger the cache the more improvement you see (although there are diminishing returns on this), but also the more data you lose in the event of power loss or kernel crash. So it is a tradeoff between speed and resilience.
Interesting thought about how this changes for SSDs. While you don't have seek times to consider anymore, if you have two writes that happen to fall on the same block in the SSD it is a big win to combine them, so SSDs still want to buffer data and have to make the speed/resilience tradeoff.
You're talking about something else here. Linearized writes means write the data immediately, but rather than write the data to the 'correct' location on disk, just write the data immediately after the last bit of data you wrote.
Then keep some accounting information elsewhere to map the real location of data to the place it would have been written had linearization not been done.
That sounds awful from a fragmentation standpoint, but I guess it would be ok for write-mostly data. That metadata map would get pretty gnarly if you have a lot of interleaved writes though.
> theoretically possible to linearize a random write workload
Are there filesystems or databases which are specially designed to optimize for this constraint? It would basically boil down to structuring your whole system as a set of interlinked mostly-append journals.
Bigtable is exactly this. An entire database is saved in a small number of files which are are append-only (and therefore can be written fully linearly).
Reads of a single record usually only read a single disk block. In-memory indexes to locate the block are fairly small, even for 1B+ records.
Reads of a range of records do N range reads of blocks, where N is typically < 5, and the number of bytes read compared to the number of bytes returned to the user is typically <10% overhead.
Rebuilding is not random i/o though, it goes sequentially and that's what SMRs are good at.
Still, I did recently reshape from 4x6TB raid5 to 5x6TB raid6. The new drive was SMR WD Red, it took 12 days and I was quite pissed when I found out the SMR bit. It wasn't in the datasheet, if I knew upfront, I would never bought it.
SMR has a terrible rep for a reason, and no one with any knowlege of what SMR is would buy which is why they have to be unethical by removing this spec from the spec sheets
SMR is cheaper for them to manufacture, and is TERRIBLE technology that really has very little actual use case, except Archive storage. The manufacturers want to push SMR for more than that because it is more profitable for them
> SMR is cheaper for them to manufacture, and is TERRIBLE technology
It's not that terrible if the customer knows what they're getting. It's just that SMR competes with tape more so than with conventional (CMR) hard drives. Many workloads are good enough for SMR.
That's true. There would be no issue as long as the fact is clearly displayed in data sheets. The problem is not really with SMR, but with hiding the fact.
You don’t need to write the entire drive sequentially with SMR, it’s just that you need to write sequentially within a given “chunk” of data. So there are some workloads that can, at least in theory, work on SMR. Think of object storage or log-structured data.
With proper system design and tiered storage, it would fit a lot of archival uses if it's visible.
Things like data warehousing, where you would want to store on something else for the current time period, but could store a big blob as the data gets finalized (once all nodes have reported in, or maybe after N days if you drop some columns at that time). Or household archival where data basically doesn't get changed once it's put on the storage --- wait for a block sized write to accumulate and then do it (need a different tier for the intermediate writes... Some SMR drives have a PMR section for this too).
But, device managed SMR is not a very good solution, even if the use case would be good for SMR, because the filesystem is most likely not aware of the need to cluster writes.
Once the software problems are fixed, then just about anything you might want to put on a NAS is suitable for an SMR drive. Big files work just fine. Put all your big media files on it. Little files are fine in limited amounts, or in occasional bursts. You could install a program to it, but you wouldn't want to put your user folder on it. Don't put cache or temp files on it, or a database. Don't put a virtual machine's disk on it, since that implies an internal filesystem that doesn't know about the layout.
With a filesystem that understands the layout, they're almost as good as normal hard drives. With a filesystem that understands the layout and $3 of flash, you can make something that solidly outperforms a normal hard drive, at a much lower cost.
Also tape drives are too expensive for normal consumers.
The latency difference means the two are suited for very different real-world workloads. But they're similar enough in the access patterns they prefer that the software work to make your IO fit those patterns can be shared between SMR and flash.
The latency difference means that the access patterns are extremely different in practice. Even random reads get really painful on SMR since they get structured as logs that need to be replayed.
I’m still confused how SMR is suitable even for archive storage. The drives slow down tremendously when doing long sequential writes. I don’t think tape even does this.
Tape is pretty constant. It has a (let say) "optimum" throughput, and as long as you get the data to the drive controller fast enough that's what it'll do.
If you don't then the tape drive write speed falls off pretty quick as it does stuff to cope.
> SMR has a terrible rep for a reason, and no one with any knowlege of what SMR is would buy which is why they have to be unethical by removing this spec from the spec sheets
I have a couple of 8 TB Seagate SMR drives i use for backup, and for that purpose they've been great. They're cheaper than PMR drives, and i honestly don't care if the backup takes an hour extra to complete.
Unless you're in a business scenario, how much of your data on your x*8TB drives at home do you actually write to on a regular basis ?
Half of mine is family photos, backups of clients, movie/music media, etc. For this purpose SMR also works well.
I'm far more worried about power consumption for NAS drives than write performance.
DM-SMRs aren't good at sequential I/O. They're bad, just not pathologically bad. SMR drives still need to stage sequential I/O to the cache area, but they at least get to write it out without a ton of write amplification.
With extra inefficiencies, yeah, SMR drives will only be a few times slower than regular drives for sustained sequential write workloads, as opposed to thousands of times slower for random writes.
Real host-managed SMR with SMR aware filesystems and storage engines might be OK, but that's not a thing in the consumer space.
That has to hurt the aggregate write performance on the array. You hand it a big chunk of data and it goes ok, calculate the FEC and write to disks 1, 2, 3, 4. And disk 1 is done, disk 2 is done, disk 4 is done, ... , ... , ... , disk 3 is done, now to tell the OS the write is complete and to send me the next chunk.
That's a problem. I have been using and recommending WD to everyone who asks me what drive they should buy (based on backblaze data and 20 years of personal experience) for their private and everyday usage. Even though these are NAS drives it tarnishes the brand.
What Backblaze and experience show is how drives of a certain brand performed a couple of years ago, not how the drive you just bought will perform.
IBM used to be very good until Deathstars, and now HGST, who took over is among the most reliable. I used to be very satisfied with Seagate, then ST3000DM001 happened, and now, it looks like they are slowly getting back on track. Maybe it is WD turn right now. I don't think there is a way to know until it is too late.
Personally, I like to make RAID mirrors with drives of different brands, or at least different models. Even it it is not ideal for performance, it helps making sure that not all drives fail at the same time.
IBM had one batch of bad drives and a second batch of somewhat iffy drives after many years with an excellent record and suddenly nobody ever trusts them again. Meanwhile Maxtor put out crap drives year after year and nobody seemed to mind. It was a very weird situation.
FWIW however I bought some HGSTs a couple of years ago that are by far the loudest drives I've ever used. They've been reliable thus far, but the noise level is so bad that I had to move them away from where the people are working.
I loved and owned quite a few 2.5" HGST travelstars. There were capably of takig insane abuse and worked just fine. Interestingly enough I never got to buy the 1.5TB ones; by the time I needed one it disappeared off the market, the website, everywhere. I never knew why.
^^^ those are a working, happy disk; all due to a "feature" that was on in Ubuntu by default that wanted to idle/spin down the disk every other second and it took me a while to notice.
On contrary I'd worn a 2TB 2.5" Seagate out in 2 years. Bought it new, put it in the same machine the 1TB HGST had been running for 3 years already, the Seagate died earlier - or at least that's what ZFS told me. It's spinning, but it throws weird errors from time to time.
I never had experience with 3.5" Hitachis.
Eons ago there were some interesting disks in the market though; if I remember correctly my father had some Fujitsu SCSI160 or 320 drives which had their normal working temperature around 50-60C.
Yeah, it would have been nice to know how loud the HGST would try to be before I bought one. But stuffing it in an isolating bracket like this basically fixed that: https://www.amazon.com/gp/product/B07LCD2RJY/
I guess they are same design as Toshiba DT01ACA series. My 10-years old Barracuda was barely audible drowning in fan noises, but this new Toshiba seeking is obnoxiously loud.
Not so sure that helps in this situation. FreeNAS users are reporting these drives failing to resilver, which _could mean_ that you end up with a failed array and data loss instead of a failed drive. I'll personally be staying away from WD for a while. I'd rather drives fail prematurely than be a ticking time bomb.
Probably not. The permanent need for power to avoid data slowly disappearing from the device pretty much makes SSDs a non starter for long term storage.
That’s not what the article says. The article says that consumers are overreacting, but that SSDs can and do lose their data with loss of power and/or heat.
I feel like we are a long way off from that just based on price. Generously I think we can say a 1TB SSD (sata even to go cheaper) is about $100. That compared to a bare WD Red 8TB which comes in at ~$27/TB. ~4x the cost and smaller drives is a hard sell (even with the speed). I have a pool of SSD's that I keep some stuff on but the rest goes to spinning rust.
Indeed. According to a newer article [0] on the same web site:
> Some Seagate Barracuda Compute and Desktop disk drives use shingled magnetic recording (SMR) technology which can exhibit slow data write speeds. But Seagate documentation does not spell this out.
> Personally, I like to make RAID mirrors with drives of different brands, or at least different models. Even it it is not ideal for performance, it helps making sure that not all drives fail at the same time.
This is exactly my approach lately, and it works great for RAID10 arrays (where you only need 2 or 3 different vendors - one per side of the mirror - to mitigate shared bathtub curves). I usually go with SSDs nowadays, though (half Crucial, half Kingston), both for performance reasons and because they rebuild faster (and also because the limited lifetime of flash memory makes some sort of RAID essential for longevity, though this has been less of a problem with modern flash tech); if I really needed the capacity of magnetic media I'd probably opt for a WD / Toshiba split.
What do you recommend for Crucial and Kingston SSDs?
I’m familiar with Crucial BX500 and Kingston UV500. They are both SATA and are decent performance considering the limitations of SATA 3. If price isn’t a factor or performance is important I’d go with a Samsung 860 EVO or Pro on SATA. I’ve also used a smaller number of SanDisk by WD SATA SSDs and they work fine as well. Had a bad Samsung 840 series but I think failure to implement proper overprovisioning was to blame. Also had a bad Intel SATA SSD but it was an older generation product and had a small sample size of only a few Intel SSDs, so not writing Intel off; yet it’s suffice to say their products don’t seem price competitive with Samsung’s offerings.
As for NVME SSDs I have used and installed probably ten so far but I think every single one so far has been a Samsung 9xx m.2 and I’ve been extremely satisfied with all of them, especially the 960 series EVO and Pro and moreso the current gen 970 EVO Plus and Pro.
Honestly I just go with whatever's cheapest for a given target capacity (which, judging by my Amazon and Newegg purchase history, would be the Crucial MX500 and Kingston V300). Any SSD's almost always "fast enough" for my purposes (even with SATA instead of NVMe), and Kingston and Crucial have both been consistently reliable enough that I haven't felt the need to splurge much (and if they do fail... well, that's what RAID's for, right?).
Both the desktop on which I'm typing this comment (my personal "gaming" rig) and my work laptop (a Thinkpad T470) are using Crucial MX500s (1TB, M.2); the former has a couple extra M.2 slots, so I'm considering migrating to a Crucial P1 + Kingston A2000 combo (thus biting the bullet and switching to NVMe, and getting RAID going on this machine). Most of my 2.5" purchases tend to be Kingston V300s unless the MX500 happens to be cheaper (e.g. most recently for an old XP computer I'm rebuilding for a family friend) or I'm specifically buying both for the aforementioned purpose of RAID diversification (which is a bit tricky, since Crucial and Kingston use different increments for capacity, but I'm also perfectly willing to pull a bit of a SSD "no-no" and use the leftover space on whichever drive for a swap partition, or else just let the space sit unused, or perhaps use it for temporary files where I don't care about any sort of data preservation).
In any case, no complaints with any of 'em. I haven't tried the P1 or A2000 yet (let alone Kingston's pricier KC2000), so I can't attest to those, but the MX500 and V300 have both proven to be reliable workhorses.
I'll definitely be sure to try Samsung again at some point; the first SSD I ever bought was a Samsung (at Fry's), and I had pretty awful experiences with it, but that was back when SSDs were a pretty new concept so I'm guessing things have generally improved.
Personally, I like to make RAID mirrors with drives of different brands, or at least different models. Even it it is not ideal for performance, it helps making sure that not all drives fail at the same time.
i do that too, and effectivele that means i had to get one of each brand available. the choices are really limited here.
I think Seagate has always been low on reliability; the ST3000DM001 is an outlier but I've heard far more reports of data loss from them than any other brand. The number of threads in HDD recovery forums that refer to a particular brand makes for an interesting analysis... and even before that outlier they were below WD. From what I've seen, WD is somewhere in the middle.
My beard must be grayer than yours. In the 1990s and early 2000s, Seagate was the gold-standard for reliability, and they were priced accordingly. We literally bought nothing besides Cheetahs for our data center for more than a decade. So did everyone else.
Past performance does not indicate future return, but so far I'm seeing no reason not to distrust Toshiba hard drives at the very least given the Backblaze stats. I've bought 8 Toshiba drives with zero problems over several years on aggressively used drives but I've had several failures across drive families over the past 10 years with Western Digital drives of different batches and lines.
One of the dangers of blending drives is that there are sometimes drive geometry incompatibilities that can screw up RAID. Saw someone show they had drives that are a few cylinders off and can't replace drives now with certain replacements.
> Past performance does not indicate future return, but so far I'm seeing no reason not to distrust Toshiba hard drives at the very least given the Backblaze stats. I've bought 8 Toshiba drives with zero problems over several years on aggressively used drives but I've had several failures across drive families over the past 10 years with Western Digital drives of different batches and lines.
Are there too many negatives there? It seems that you first say that you distrust ("no reason not to distrust") Toshiba drives, but then you say that your experience with them has involved no problems.
Some HGST tech is Toshiba now, some of it is WD. Hard to know whether WD drive is made up to HGST snuff. If you want the best, buy helium WD drive labeled HGST. If you can't get it, then WD or Toshiba helium datacenter drives should be close.
That's what I'm wondering though. Nearly all the WD data center drives are marketed as Ultrastar. Is this marketing, or did the HGST entity supplant WD enterprise during "integration" in the last two years? https://www.westerndigital.com/products/data-center-drives#h...
It looks like the only surviving product names are Ultrastar and CinemaStar. Nothing is labeled HGST anymore. Most of the HGST Helium disks were SMR, if I'm not mistaken. As of now, given the two HelioSeal series, one of the two is SMR.
Side Note: Hitachi had such a great thing going with their Schoolhouse Rock meets Dino DNA commercial. I wish this would have continued. https://www.youtube.com/watch?v=xb_PyKuI7II
I've been in the WD camp since the 90s but Backblaze's data has always ranked them around "better than the worst" and slowly eroding my confidence in them.
For me, Backblaze's Stats have changed my perception of HGST who I've held in low regard since they were IBM with the whole Deskstar issue.
The ridiculous thing is that nobody would have batted an eye if they did this with Green/Blue drives, especially if they just owned it upfront. I still don't particularly get the difference between Red/Green, or even Red/Blue for that matter, apart from opaque firmware tweaks about power saving, and some hand waving about chassis vibration. SMR/PMR would have been an obvious partition.
I still can't fathom how companies can be so oblivious about their actual customer market. People speccing individual hard drives are integrating their own systems and want to care about the details, not just some colorful indicator of "good/better/best".
They apparently still care enough to create all those Red/Green/Black/Blue/Purple/Gold lines. Even if those are really just a few different #defines and different ink in the label printer, they're still additional SKUs. Also the margins seem plenty high given you can shuck 8TB Easystores for $130, with the retail version at ~$200.
And yeah individuals can never really do anything in the short term. Eventually there will be a suite of best practices to test a new drive to make sure it's not SMR, and likely some tweaks to filesystems to ratelimit rebuilds, based on knowing which drives are actually SMR. But they're arbitraging away brand loyalty to WD Red, for a short gain. Given the goodwill they enjoy(ed) from that Blackblaze study creating a refrain of "don't buy Seagate", this just seems foolish.
The product lines were driven by the fact that margins were low: attempting to decommodify via artificial use segmentation.
Shucking has always had weird economics. I think mostly because it's used by the manufacturers as a release-value for excess capacity, in an attempt to somewhat avoid the memory chip boom-bust cycle.
No file system should be doing random writes, and when you have a cluster, there is always an open stream you can append to. I agree this is a bogus move, but tech with analogous limitations but also similar enhancements will make it into more things.
If risk and failure were spread more evenly, systems would behave more like gas and less like a ceramic.
A typical size for a SMR zone is 256MB, and any writes that aren't appending sequentially to what's already been written to that zone count as "random writes" on a SMR drive. That's an absolutely massive block size to expect filesystems to work around, and I doubt there are any commonly used filesystems that can store their metadata in a SMR-friendly way.
Metadata belongs in persistent storage (PMEM or flash), file contents can striped onto a magnetic disk. Flash suffers from the same problem. Rewriting a file should be appending binary diffs to a log and reapply the writes against the first version into a new location on the cluster.
SMR is extremely painful for anyone except those that can handle distributed storage systems. I think the only place where SMR makes sense for home users is in a DVR, or game assets where a virtual disk is streamed down from a cloud provider in a single pass, and no interior mutations.
Ok, so when you say "no file system should be doing random writes", you should make it clear that you're not trying to describe file systems that actually exist in any sort of production-ready state. I would generally agree with a statement that new filesystems should be designed to avoid random writes except to solid state media. But for users wanting to deploy a real filesystem now to commodity hardware, the recommendation has to be "avoid SMR", not "use a smarter FS and tiered storage hardware".
Correct. SMR should be sold to tiered storage providers OR SMR drives should include a scratch flash or pmem device to hide the large write amplification of rewriting a block (ala back to tiered storage).
HN is fringe, I am not making statements about people with drobos.
For many copy-on-write or log-structured filesystems it's not particularly hard to adapt them to such a block size, but I don't think it has actually been done on a major scale yet.
I worked for Hitachi during that time period and that is mostly true. Hitachi actually sold the division to WD in exchange for private ownership shares of WD with insane leverage because WD had most of their factories flooded in 2011.
WD Drives were actually HGST drives with a different label for several years.
I have stopped buying WDS and Seagate (their 3tb drives failed sequentially in my zraid in 4 months and I just barely replaced them with new). And I am not buying even brands that were merged with them (here is picture how hdd brands "consolidated" https://www.mydatarecoverylab.com/wp-content/uploads/2018/07...). Those companiea must be punished (by not buying their products) for all the mischief they have done to our data for the sake of maximising revenue, they need to be aware it will hurt their bussiness.
Now I am having 3xToshiba drives and one Hitachi and for now I am happy.
Does the revelation that they use SMR somehow change their reliability or performance ?
I fail to see how it makes the drives any less useful only because it is revealed that it is SMR and not PMR.
It is models from 2TB to 6TB, meaning pretty much all NAS drives purchased in the past decade.
I don't know about yours, by my drives perform just as well as they did yesterday.
>Shingled media recording (SMR) disk drives take advantage of disk write tracks being wider than read tracks to partially overlap write tracks and so enable more tracks to be written to a disk platter. This means more data can be stored on a shingled disk than an ordinary drive.
>However, SMR drives are not intended for random write IO use cases because the write performance is much slower than with a non-SMR drive. Therefore they are not recommended for NAS use cases featuring significant random write workloads.
[...]
>We brought all these points to Western Digital’s attention and a spokesperson told us:
[...]
>"In device-managed SMR HDDs, the drive does its internal data management during idle times. In a typical small business/home NAS environment, workloads tend to be bursty in nature, leaving sufficient idle time for garbage collection and other maintenance operations."
That seems like a pretty notable difference to me. You probably want to know that ahead of buying the drive.
> Therefore they are not recommended for NAS use cases featuring significant random write workloads.
Emphasis mine: a NAS featuring "significant random write"s, is not the usual NAS, and might not actually be best described as a NAS at all.
In WD's terms, they'd tell you that if you've got e.g. your /var partition mounted over SMB to your NAS, then your NAS is receiving a Desktop workload, and so you should use their Desktop drives in it, not NAS drives. (Consider: the drives backing Amazon EBS—which receive Server workloads—are certainly not "archival media" disks, despite being nominally "network-attached storage" disks.)
The use-case for WD Red (NAS) drives is online archival media storage. Like S3 without the high availability. In other words, the thing most people buy a NAS for: backups and home Plex hosting.
This is why, I assume, WD don't literally call these drives "WD NAS", but instead just call them "WD Red." Just because you put them in a NAS, doesn't mean they'll function well there. You have to be using them for an idiomatic NAS workload. (Which also means that WD Red drives fare just fine in a desktop or server, too, if you're using them there purely for an idiomatic NAS workload.)
>In WD's terms, they'd tell you that if you've got e.g. your /var partition mounted over SMB to your NAS, then your NAS is receiving a Desktop workload, and so you should use their Desktop drives in it, not NAS drives.
That's still obfuscation bordering on scam IMO, if the drives have technical limitations they should be spelled out, not hidden behind broad terms like "NAS drive", especially when they're branded the same way as older drives that didn't have these limitations.
Also, you'll have to explain to me how having these drives perform correctly while rebuilding a RAID array is not a "usual NAS" scenario. Because reading TFA it seems like getting these drives in a NAS to begin with is a challenge on its own.
Yeah, that seems pretty scummy to be. I was under the impression that "NAS" drives were objectively better than "Desktop" drives.
The clerk at the computer shop tried to upsell me on the NAS drives, chortled when I said "the "I" in RAID stands for "Inexpensive" and told me that I would regret my purchase.
It seems to me that my cheapness inadvertently paid off?
That's all well and good, but, given a sufficiently large array, it's a matter of when, not if, you'll need to recover from a failed disk, rebuilding a RAID array is precisely the expected sort of workload for a NAS — and a workload that reports indicate these drives fail at.
Except they don't, because apparently SMR is slower to write than conventional recording, so the device buffers writes to conventional tracks, then uses idle-time to re-write the buffered data to SMR tracks.
About 80:20 by units sold, I would say; leaning slightly more toward the latter by volume of drives sold, by the fact that businesses buy the larger NASes that take more drives in them, because they're actually somewhat serious about RAID recovery.
But you've got to further subdivide the use-case: a file server for a business is still not necessarily doing "random writes." You can create and replace as many small files on a filesystem as you like, and in a modern filesystem, you'll only be doing large batched writes to the disks themselves. It's only when you're writing within existing files—i.e. writing to a database of some kind—that you see a high number of random-write IOPS hitting the disk.
Mind you, there are a lot of things that turn out to have databases in them. A Chrome profile has a couple of SQLite databases in it. An iTunes library contains a database. Etc. These are the things that—if you stuck them on your NAS, and then pointed the relevant program at them from your PC—would constitute the NAS performing a "Desktop" workload. And, obviously, if you run Postgres on your NAS—or on a system that mounts a NAS disk over iSCSI—then that disk is doing a "Server" workload.
But the average business's use of e.g. shared Excel worksheets, does not "heavy random writes" make. Document/productivity software is almost always of the "on save, do a streaming overwrite of the whole file on the remote end" variety—which, again, is not a random-write workload, since the ftruncate(2) at the beginning allows the filesystem to grab a new free extent for the overwrite to write into.
Most software that knows that it can be used in a shared-remote-disk setting is built to accommodate that shared-remote-disk setting by attempting to minimize random writes (since this kind of workload has always been slow on the kind of storage used in NASes and SANs, especially when your filesystem or software RAID does checksumming.) These days, it's only the software that absolutely can't help it—that needs random writes to be performant at all—that still does them. And it's pretty obvious, to anyone using such software, that they're not using "NAS friendly" software. Mostly because it's so dang slow!
>Does the revelation that they use SMR somehow change their reliability or performance ?
Yes, they do not perform anywhere like PMR on writing.
It's so bad they simply should _never_ be used on a RAID or Zpool, where they have such pathological behaviour on resilvers that can easily become the trigger for data loss.
I would never buy one of these voluntarily, as they'd cause me headaches.
So, definitely, I need to know whether what I am buying is SMR or PMR. And wd's behaviour is unacceptable.
Yes, they perform worse, but there is a bigger issue. They lie. The drives report themselves as being PMR when they should be reporting themselves as SMR. They actually lie about their technology type in the firmware.
The article implies that's only recent revisions of the 2-6 TB products that use SMR, noting issues with "the latest iteration of WD REDs (WDx0EFAX replacing WDx0EFRX)"
Trust is a bitch - so hard to gain it, and very very easy to lose by doing shit like this. I was buying WD/HGST drives for work. Now, I have to test everything I buy before deploying them dammit.
It seems pretty calculated to reduce costs while deceiving the buyer by omitting or having an incorrect spec sheet.
Would a class action suit help to prevent this kind of action in the future? Perhaps the punitive fine will make the cost calculations that led to this decision different since they will need to include the risk of judgement in the costs.
I would imagine not. The class action would settle, most consumers would get a trivial sum in the form of a check, and the litigating firm would get a large payout. The settlement would result in no one taking responsibility for anything.
Aside from the other mentioned issues, a significant part is also the lack of retesting. WD Red drives aren't a fancy new thing and have been on the market for years now. As a result a test of the same drives is unlikely to give you a whole lot of revenue, since it's a known old product. People don't usually care a lot about yet another test with the same results. As a result retesting isn't really worth your time _unless_ you find something significantly changed (like in this case). Also running a useful test is non-trival as you'd need to source a significant amount of platforms, comparision products and setup a testing environment for it. Testing a brand new (CPU|GPU|SSD) instead would be much more likely to attract new readers and increase revenue.
Manufacturers have slowly started realizing this circumstance and are obviously able to exploit it by making products cheaper to manufacture down the line.
On the SSD side of the storage market, I know it's becoming more common over the past ~2 years for manufacturers to change drive internals without changing the model name/number (for consumer drives only). In the past year, I've had one brand proactively bring it up as part of a product announcement presentation and two other brands have mentioned it in the course of an extended conversation about their entire product line. For the one company that mentioned the hardware update in their press release, I asked if they could get me a review sample of the new revision, but the drive that arrived a few weeks later was the old version.
Most of the updates like this in the SSD market are actually pretty harmless—switching a SATA drive from 64L to 96L TLC generally isn't going to change the performance or power characteristics enough to care about, and is more likely to be beneficial than harmful. But when they start introducing QLC NAND into a product line that originally was TLC-only, that's a problem.
> Manufacturers have slowly started realizing this circumstance and are obviously able to exploit it by making products cheaper to manufacture down the line.
I believe this is a known technique in mass-produced markets. Called 'debasing' or something like that. Even new cars have more bells and whistles when first released while as the model gets a stead consumer base the manufacturer might reduce accessories or get cheaper versions, etc.
There’s an analogue here in the concept of shrinkflation. To my mind debasing occurs in capital purchase items that last years or for life to take advantage of the only opportunity to double dip on the single sale. Shrinkflation seems more applicable to commodity goods that are often consumable or single use, the hidden price increase of which causes larger impacts to ROI and and profitability as well as cost to the buyer. These factors combined make shrinkflation perhaps more impactful overall to the economy due to the frequency and necessity of such goods.
If you pay too much for too little on your car, oh well. Its probably too late to do anything about that now or you would have returned it to the seller already. For most people they settle for enough car for enough money. You can always add aftermarket parts or customize it, because there is a large secondary market waiting to make your outside investment even more worthwhile to your own judgement. If you pay too much for soap, it’s not even worth it to return it to the store in your time or your money so the market simply wins. It’s a rigged game akin to Las Vegas house games.
As buyers it’s just stressful being so wary all the time. I don’t know what the better way is but surely it must exist, we just haven’t made it profitable enough yet for the right people.
Yes, you will notice this, even if you do a simple write test with only big writes at full speed. After a while (about 2h in our tests) these drives become "tired". You need to leave them be for a few hours and then they are fine again.
An added problem is that the usual candidate file systems (ext4, xfs,...) do not combine well with SMR.
Some people might be able to put these drives to good use, but only if they know up front that it's this kind of drive they are getting.
That's a good way of explaining it and makes sense. I have 3x4TB WD Reds configured as an 8TB RAID 5 mdadm array in my Linux box. It's a sort of dumping grounds for backups/disk images, VMm images, etc. I would see initial write speeds of 150-200MB/sec but during large transfers moving 100's of GB, it would drop in write speed down to 50-60MB/sec. I thought it was a performance issue in the kernel or with mdadm and didn't bother to investigate further because I'm not a datacenter.
Because with DM-SMR drives there is usually a non-shingled area on the drive used as a buffer. Once the buffer is full, performance tanks dramatically as tracks are being rewritten. This is especially true in my experience when writing lots of smallish files vs several very large files.
don't assume that if you hire a volume on AWS that you get a device. The thing you get is a virtual block device and is actually the entry point of a sophisticated piece of software that will spread your data over multiple devices (might be erasure coded, might be replicated, probably hierarchical, so data comes in on NVMe, is then moved to SSD and eventually to HDD). So whatever you're seeing, it's not the behaviour of a single HDD.
Yes. I remember two years back when a small (really) independent french journal called CPC Hardware was able to publish a full review of the latest AMD CPU a month before everyone else in a bimonthly paper issue: they simply sourced the chip on eBay instead of signing NDAs like literally every other publication.
My guess is that a decent review of a hard drive takes a non-trivial amount of work: review unit acquisition, test setup, test execution, test repetition, analysis, writeup, publishing, ...
And that work needs to be paid for.
And nobody buys review magazines any more.
And advertising revenue on review sites can only pay for a small handful of SKUs to be reviewed. So only the sexiest, mass-marketest units get reviewed.
And the vendors fly under the review radar by flooding the market with so many variants that there isn’t enough funding to review more than a tiny fraction of them.
And by the time any headway is made into reviewing current models, new ones are released and suddenly nobody is interested in the old ones, further squeezing the window of opportunity for advertising revenue. And eliminating entirely the incentive for long-term testing.
Meanwhile, review sites realise they can get paid more in bribes/freebies/access than in advertising, and either outright compromise their reviews or only report the hits and never the misses.
And so consumers are flying blind, trying to extract signal from the noise of furious churn.
>And so consumers are flying blind, trying to extract signal from the noise of furious churn.
I think this is true for almost any product nowadays that isn't in a ridiculously small niche.
Most non-niche products on Amazon I've found get a poor score on "FakeSpot".
I believe someone even admitted on reddit that he/she was actively creating fake reviews and fake stories about certain boot brands on relevant subreddits.
Unfortunately you can't trust anything online anymore. You need to spend hours or days researching the technology or product category in order to make a judgement on the products available.
Yes, I've been buying WD for what, 15-20 years (I'm just a domestic user, fwiw) .. these sorts of things signal "we've decided to burn the brand to make short term gains", like when venture capitalists take over.
> Meanwhile, review sites realise they can get paid more in bribes/freebies/access than in advertising, and either outright compromise their reviews or only report the hits and never the misses.
Pretty much. Like the rest of news, accuracy is expensive, entertainment is cheaper, and anyway the audience prefer the latter.
Putting together a decent automated test suite is possible, but is a significant project for an individual drive reviewer. And any test suite you create is only good for a few years at most before you have to start worrying about new technologies that change performance or power characteristics in a way your tests can't capture. If you were putting together a hard drive test suite a few years ago to use for reviewing consumer/prosumer desktop and NAS drives, testing specifically for SMR behavior may not have been on your radar.
Well, the OP mentions that these drives are dropping out of RAID arrays during rebuilding operations. Some people might describe that as a reliability concern.
"For Backblaze Vault Storage Pods each is one of 20 pods needed to create a Backblaze Vault. A Backblaze Vault divides up a file into 20 pieces (17 data and 3 parity) and places a piece of the file on each of the 20 Storage Pods in the Vault. We use our own implementation of Reed-Solomon to encode and distribute the files across the 20 pods, achieving 99.99999% data durability. We open-sourced our Reed-Solomon encoding implementation as well."
Backblaze's main reliability system is erasure coding[4] of shards of files, which is not RAID[1][2]. RAID mirrors disks or volumes on block or filesystem layers, not files in userspace.
That being said, I stand corrected in that they did use RAID at some point in time[3] (RAID6 on 13+2 drives), and may still be using some form of RAID. OTOH their reliability calculations don't seem to consider RAID - calculating with individual drive failures and shard rebuilds.
For these large scale infrastructures, they typically use JBOD, i.e. no RAID whatsoever and they achieve redundancy by maintaining multiple copies of the data over multiple disks spread around the datacentre. So it's not hardware RAID that requires a certain response time (I suspect the drives mentioned here drop because they timeout as it take a long time to random write on an SMR disk), more like a distributed software RAID. I think they likely also have their own file system so they are not dependent on a fixed block size, which allows them to save space if they have loads of small files.
I think that's about half right: for large storage infrastructure, you would indeed eschew local RAID, but instead of storing multiple copies, you'd use Reed Solomon encoding to stripe a single copy across many disks/servers/failure domains with a configurable number of added parity stripes. Full copies are really expensive!
RAID only protects you from disk failures, not machine failures. If you want to protect against machine failures (whole server offline), which might be an availability concern, then you would naturally want to replicate the data at a higher level. Once you’re doing that, it makes sense to only replicate the data at a higher level, because for a given level of safety, it is more efficient to replicate the data once, in one layer, than to replicate the data multiple times, at multiple layers.
RAID is only effective for workloads small enough that you care about a single machine.
It's a similar idea but they distribute the copies between machines, not just across disks in the same machine. https://www.backblaze.com/blog/reed-solomon/ So the drives in each box are not in a RAID configuration.
Hardware RAID typically requires a disk to respond within a certain number of ms, either reporting a successful write or a failure to write. SMR, because it requires a whole section of the drive to be re-written everytime you need to modify a single block of that section, may have very slow response times, and result in timeouts. On a timeout, the hardware RAID controller assumes the disks is offline and drops the disk from the array.
The same happened with WD Green drives, which are not graded for RAID. Their error correction logic typically allows for a lot more attempts to read the data than a datacentre drive, resulting in timeouts and the drive dropping out of the array (which is why it is a very bad idea to put a consumer drive in a hardware RAID array).
Now WD Red NAS are meant for RAID arrays but I suspect WD assumed they would be used for software RAID only, which typically doesn't have those timeouts. But if so, it should be clearly stated.
Isn't that behaviour of Greens only a problem when the drive goes bad? In which case you want it to get kicked out of the array. Or do you mean this will happen to a new Green drive with too high a probability?
The problem is that taking some time to read the data doesn't mean the drive has gone bad, at worst perhaps a sector has gone bad, and even then, it might even still be readable, just a bit slow. And apparently it is very common on large capacity green disks after a few months.
The typical bad scenario (and I have been burned by this) is that let's say you use RAID5, and one sector goes bad. While the disk tries to read it, the RAID controller kicks the disk out of the array because of the timeout. Now you need to replace the disk and rebuild the array. In the rebuilt, as you are doing a full read or all disks, you are pretty likely to find another sector that is slow to read on one of the other disks (particularly on multi-TB disks). And then the controller will kick another disk from the array. And now you lost everything.
Also why data scrubbing is pretty important in NAS.
Thanks for explanation. That was surely a bad experience. Luckily there are ways to overcome this incompatibility, such as increasing the timeout value for a drive in the OS, see the Linux wiki
They have long (deep) error recoveries, and most of them don't have configurable SCT ERC. If used on Linux, where the default command (queue) timer is 30 seconds, a bad sector could result in the drive not reporting success or failure well beyond 30 seconds at which point the kernel does a link reset thinking the drive is unresponsive. On SATA drives, resetting the drive clears the whole queue, all commands are lost, so it's not clear what sector has the problem. This prevents whatever healing properties RAID has. e.g. on md RAID (includes mdadm and LVM managed RAIDs these days) an explicit read error by the drive comes with a sector LBA value, and md will know what stripe its a member of (or its mirror) and will overwrite the bad sector with reconstructed data, fixing it. But if there are either write errors or a bunch of link resets, md will consider the drive faulty (kicking it).
It's important to know this kernel command timer and SCT ERC mismatch is (a) common and (b) affects mdadm, LVM, Btrfs and maybe ZFS RAID on Linux. I'm not really sure whether the kernel command timer applies to ZoL or if a vdev has its own policy.
I dont know of any independent review site besides BackBlaze.
Most review sites receive product samples from the manufacturer. The linked article shows that the disk manufacturers cannot be trusted.
I bet they did not send out DM-SMR drives to review sites.
"Which?" in the UK do pretty good consumer reviews for domestic goods IMO. Though in general they have a problem of always picking the most expensive products, usually they give enough info that you can get a substantially cheaper item with practically no loss.
There are, but it's a moving goalpost. Consumers are chasing yet unbiased reviewers, while companies' marketing departments are busy bribing the next generation of reviewers.
At least in IT we have Stallman-esque zealots who refuse to be bribed. I don't think we have the equivalent in other markets unfortunately.
"The Synology forum poster said he called WD support to ask if the drive was an SMR or conventionally recorded drive..... the higher team contacted me back and informed me that the information I requested about whether or not the WD60EFAX was a SMR or PMR would not be provided to me. They said that information is not disclosed to consumers"
I don't know or care about shingled, thatch, whatever, but I am not going to entrust my irreplaceable data to a vendor that refuses to tell me or anyone else what they are selling.
My understanding is that the SMR drives are like SSD to a degree that they needs rather intelligent firmware to place the information on the disk.
At the moment everything is sitting behind the bogo SATA disk interface which was never designed for this type of storage - rapid burst writes to the 20GB onboard buffer area and than very slow I/O as it is emptied out.
Surely a native OS interface would be better for these drives.
It's much worse than that. For SSD, it's just the blocks need to be zeroed before being writing to, which is not even an issue if there is lot of free space.
But for SMR, the reading track is narrower than writing track. For example, reading track's width is 1 unit, writing track's width is 2 unit, there is a 1 unit overlap between two adjacent tracks.
And here is how it works, assuming writing sequentially:
1. Start with blank disk, and write to track #1. This is happy case, as no data there, we can simply write to it.
2. Write to track #2. Still can simply write to it. However, this will overwrite lower half of track #1, but as long as reading only need 1 unit, track #1 record is still good.
3. Write to the following tracks one by one, all good, same story with step #2, over writing half of previous track.
4. Repeat until track #n.
5. Okay, all of a sudden, now we need to change something in track #1. What would happen now: we cannot simply overwrite the stuff in track #1 as this will overwrite the top half of track #2, which is the reading track of track #2. So we'll have to read out track #2 and and write track #1 and then write back track #2, which in turn has to read out track #3 and write track #2 and write back track #3...
6. Repeat the previous operation until all impacted tracks are written back.
In reality, the situation could be slightly better: if the disk is almost empty, the firmware can always find somewhere to write to without reading out and writing back. But if the disk is relatively full, then the case could be much worse: every writing could technically trigger another reading out and writing back operation. So how long would it take to finish a writing operation can hardly be predicted.
The worse case is that the disk is full and the writing is targeting whole track #1, then almost the entire disk need to be refreshed so that it can complete the operation...
Wow. That’s how I had visualized it in my mind when I read how they work, but I figured I was wrong because it seemed too dumb and I thought there’s no way it could work like that.
Thanks for explaining.
It would be amazing for someone to come up with a “worst case write” benchmark for SMR drives.
It's worse than that. SMR drives can't do random writes without rewriting large sections. So they are entirely unsuitable for general purpose workloads.
File system journaling typically refers to a log that helps ensure filesystem consistency by recording attempted operations before they happen, but the system still has to do all the same random writes to the disk afterwards.
Some file systems (notably ZFS and Btrfs) use a copy-on-write approach that should in theory not require many random writes, but I don't think any of them are adapted for the large blocks you need to write to for SMR. (256MB?)
It should be possible to make a filesystem with drastically better performance on SMR drives given the right low-level access, probably based on something more like a log-structured merge-tree, like e.g. LevelDB.
> It should be possible to make a filesystem with drastically better performance on SMR drives given the right low-level access, probably based on something more like a log-structured merge-tree, like e.g. LevelDB.
The filesystem would need to do periodic compaction. You would necessarily encounter situations where a write to “allocated” data would fail because the disk is out of space, which is a new, surprising error that would undoubtedly confuse some user-space programs.
That wouldn’t fix it. As long as programs can write faster than the compaction algorithm frees space, you can run out of space.
The only solutions I see here are to block IO until the compaction algorithm frees space, or return ENOSPC. Both options violate assumptions that real-world programs make.
I think you actually mean log-structured filesystems.
They help with poor random write performance only at the cost of poor sequential read performance.
Both SMR drives and SSDs benefit greatly from sequential reads. A file that was randomly written will be read back in random order regardless of the reader's interest.
The Toshiba and Seagate NAS lines seem well organized and better alternatives these days. And I guess this is all the more reason to get one drive per manufacturer for the typical ~4 drives in a home NAS. Between Seagate/Toshiba/WD/HGST there should be enough variation to still protect against this stuff.
Edit: Seagate is doing the exact same thing [0], although not confirmed for NAS drives... yet. HGST is owned by WD (although the 3.5" side apparently went to Toshiba). So that leaves Toshiba.
It sucks to have to qualify drives (again?) in small businesses, thought this was a solved problem. It's more offensive they're doing it with the smaller capacities, too.
(I should note SSDs don't stand up to manufacturer's claims in error scenarios, too. But that's fairly well known I think?)
Seagate drives are notoriously poor quality, in addition to well published, large sample and long running studies by Backblaze - I ran a number of decent sized storage clusters for many years and by far found Seagate drives the most unreliable (including Seagate a rebranded as HPE etc...)
I've been using Seagate's Exos enterprise line for video processing and am very impressed with the performance. I get sustained 230MB/s write over terabytes, and while it's supposed to be slightly louder, I can't hear any difference with the case closed.
Compared to their high end consumer IronWolf Pro/NAS series they have better tech, no RAID drive limit, higher rated workload, and longer estimated MTBF. Looks even better now with the 14TB Ironwolf at $460 and the 14TB Exos at $340 on Amazon.
Agreed. I built a synology with 5x Seagate and all failed within 18 months with light workload. I will never buy another Seagate. Replaced with mix of HGST and Toshiba which are working for several years with no bad sectors. Now will buy Toshiba only until they go down the low quality road.
Buying the same brand / model drives is not a wise idea, especially if all are bought at once. Any manufacturing defects will be amplified and could cause a RAID array failure due to losing multiple drives in proximity to each other.
You are not wrong and I knew better but I was build for first time and bought all at same time. Now it's a mix of HGST, WD, Toshiba. Some are 34000h, with no issues. The WD is slower when data scrubbing but I don't trust WD for many years and that one was because other vendors were out of that size. I don't really know who to trust in that space any more so it's Toshiba for me on any new replacements.
They have a higher average failure rate but even backblaze still uses them. If you're defending against defects in product lines you want the most diverse set of drives possible to make the failures uncorrelated. Having to use drives with higher failure rates doesn't invalidate that benefit.
Anyone operating at the scale of Backblaze should also already have the right infrastructure to deal with a drive, machine, rack, PSU, etc failure without causing service downtime. (And NB that part of that will including diversifying between drive brands to guard against eg a firmware issue which affects many drives of a certain brnad in a limited time window).
What matters in that context is something similar to $/GB x (% of drives which make it to end of useful life in their application context). Cheaper drives which are less reliable might well win on that score. They might also expect to retire drives rather sooner than an average NAS user as the power cost of running older, smaller drives becomes an issue.
In an average small NAS setup the cost of a failed drive is potentially much higher. You incur at a minimum a performance penalty while the array is degraded and a significant performance penalty while it's rebuilding and have lower guarantees against data loss during that period and you can't average that out over thousands of drives.
If you've got 1,000 drives, a 99.5% or 98.5% success rate doesn't matter so much - you're going to be replacing a drives anyways. If you have 2 or 4 drives, dividing the probability that you have to replace any drives at all by a third is a big deal.
I'd say completely the opposite. If you're operating at Backblaze scale doubling your operations workload can be expensive. If you're at home doubling or tripling your chance of having to do some maintenance for an hour a year is trivial compared to the benefit of significantly reducing the chance that your whole array will fail from a common fault of all drives.
Thing about Seagate drives though is that they're usually less expensive than the competition. From my perspective, they do not have a high enough failure rate to justify spending extra on a brand like HGST. If you're doing things right, you have both redundancy and backups for your critical stuff, and in my experience Seagate is good about replacing failed drives within the warranty period.
Anecdotally, the only Seagate disks that have caused me significant headache are the Archive line that definitely uses SMR and is marketed appropriately because of it.
I've been selling and doing DR on HDD for 20 years now, and frankly speaking, Seagate drives reliability isn't the best.
Numerous new technologies led to severe issues like : 5400.6/7200.4 platter dust issues killing heads the more they heat, the infamous LBA 0 fw issue on desktop drives, motor bearing seizure on 7200.10/12, lots of bad batchs on 7200.14 ST DM001/002/003, more than WD or even Hitachi. On SAS drives, the Cheetah 15K.x are not very reliable (replaced LOTS of ST3600057SS), but the Fujitsu and Hitachi are not very either.
Toshiba drives are not great either. The 2.5" MK series had an important return rate, more than the competitors. The MQ01ABD is better, but faces platters demagnetization that leads to bad sectors.
The 3.5" ACA drives are a Hitachi prod line that was "given" to Toshiba when WD acquired HGST. They are quite basically Hitachi drives with a Toshiba firmware.
Edit : and now DR on Seagate drives like the Rosewood family (like the ST1000LM035) is the absolute worst nighmare for any data recovery guy. Ultra brittle head stack, easy platter damage when shocked, self encrypted firmware and SMR. If those disks makes some motor noise or head clicking, we don't even bother to open them anymore.
Thanks for lots of valuable information, finally someone who has some data not just a story. Could you please share more? Any source on Toshiba ACA being made using HGST tech? What do you think about reliability of helium drives? On paper they should fare much better than air drives.
Of the last 4 Seagate drives I purchased[1] 2 failed in less than 1 year - one failing after a week(!) of use. This is pure anecdote, but I don't have a lot of confidence in Seagate's quality.
[1] These were bought from 3 different retailers at slightly different times, so it's not a "bad batch" either.
Disclaimer: I worked for HGST about 3 years ago (but in the Enterprise storage (flash)/Object store fields, not consumer/prosumer HDDs).
At the time, WD was assimilating HGST's drive tech where there were cost/performance/reliability benefits to the point where quite a few 'WD' products were just relabeled HGST ones, possibly with minor firmware/logic board tweaks. I seem to recall that at the time some WD Black, and maybe Gold, models at least were rebadged HGST units. The aim at the time was to fade out the HGST brand so that everything was WD and I pretty much think that has since been done.
In the past year I've had these failures: 2x WD RED 4TB (EFRX), 2x WD RED 6TB (EFRX), 1x Seagate 4TB. I have a fairly even mix that includes HGST (and a few HGST He). No HGST failures yet. I won't be buying WD RED's for a while, if ever.
To counter that, I've been running 11x 4TB WD Red (WD40EFRX) since 2013 and zero failures, with 10 drives in RAIDZ2 and 1 warm spare.
I have them in a 4U chassis in the attic, with 5 case fans blowing through; two on the rear and three across all the bays. It's a 24 bay box, but I've not yet had pressing need to fill the rest of the bays.
Maybe they refreshed their 2-6TB line recently and not the 8-14TB and it'll come later?
Maybe the market for 8-14TB is different enough that it warrants CMS? For instance maybe the 2-6TB is for hobbyists/small companies who might not realize the drives behave differently while the larger and more expensive drives are more often use in large companies with dedicated IT who would realize something is off?
Given that TFA mainly mentions 2-6TB several times I doubt they got it wrong.
maybe the testing showed that the 8-14 would fail in rebuild but the 2-6 where small enough that would pass.
or that the 8-14 where used in "serious business" where you could not fake your way around and the smaller ones for consumers or smaller firms would not notice or could not cause bigger harm.
My guess is the want to further segment the markets so they can improve price discrimination, but they don’t want to sell a “lite” or “value” drive in the NAS segment, so they change the base model(s) to be shittier and accept the bad PR.
That way they can come out with a more expensive PMR SKU in the NAS series. SSD manufacturers did a lot of the same where features were stripped from consumer drives (PLP, DRAT/DZAT, etc.), segmented into a new market (notice the NAS SSDs?), and sold back to us as more expensive SKU.
I was wondering about this too, and I think it’s for cost-cutting on the lowest-margin products in the range.
SMR is going to reduce platter size and quality requirements for a given size in GB (because the data is packed more densely). A given capacity can require fewer platters/sides, or a blemished platter can now be used where it couldn’t previously.
For all the "can't trust HGST because its owned by WD" comments: I don't think this is the case, as HGST is still selling drives that are explicitly declared to be PMR is the datasheets, e.g. here's the HGST Ultrastar DC520 [0] which includes PMR as one of its selling points.
Eh I still wouldn't want to give money to a company that's segmented itself into a "lie to the customer" branch and a "don't lie to the customer" branch. The former will poison the latter eventually.
I would think that one would typically expect NAS drives in particular not to use SMR, especially since SMR is known to be problematic in RAID setups, etc. Not to mention the write performance issues.
It's so frustrating that all that was needed to avoid most of this was some transparency. At least list in the specs that they have SMR. It's essentially lying by omission.
But I'd probably go a step further and say that marketing an SMR drive as a NAS drive is user-hostile and destined to cause problems
Agreed. I will add that the general trend seems to assume that user is a functional idiot and keep actual specs either hidden away or difficult to get to. It is hard to make informed decisions in such environment.
The fact that WD is refusing to tell customers basic facts about their products even when called is a huge red flag. There is no legitimate reason to refuse to tell customers about whether or not you’re using SMR on a given drive.
A funny thing about device managed HMR (DMSMR) is that they extensively rely on error correction codes to recover data from overwritten tracks, and loose near all of SMR density gain to extra coding.
Why DMSMR became a thing in the first place? Windows! And non-upgradeable proprietary storage array hardware.
It seems that business people in those storage companies have put big money into SMR, but only realised that an extremely big chunk of the market cannot adopt SMR after drives shipped. And so they simply slapped a cheap and easy firmware hack on top of SMR drives to make them work with non-SMR aware software.
Where can one buy SMR drives that the host can at least reliably coerce into not using their cache/staging area? It should be quite feasible to tune/adapt btrfs to exhibit writing patterns that don't make the drive use it's staging area, but it'd still be compatible because the drive would start to make use of that staging area when needed. Some way to overwrite the superblocks without triggering SMR problems or something like that would be nice, but that's of lower importance to me, at least.
Just supporting TRIM and exposing/documenting the SMR layout/regions would be enough, I think. I'd like to buy that.
There exist "host-managed SMR" drives. In the SCSI/SAS specifications, these use the "Zoned Block Devices" command set, rather than the SCSI Block Commands (SBC) command set.
As far as I can tell it's seemingly impossible for an individual to buy host-managed SMR (ZBC) drives. Presumably they're only sold in bulk to datacentres. Maybe that could change if some demand materialised and was communicated to a suitable retailer...
What exactly do companies gain by such deceptive obfuscation and secrecy of the details about the products they sell? Especially when some testing can reveal the truth easily. It seems to be a bit of an industry trend in general, since very old HDD datasheets would specify even things like how many tracks per inch the platters have, how many heads, sectors per track, spindle motor spin-up time, etc. Somewhat recently, the WD Greens famously did not specify their rotational speed.
As I alluded to above, HDDs aren't the only things affected by this trend; SSDs, or more precisely NAND flash manufacturers, have become equally secretive about endurance and data retention. Older datasheets were freely available and specified the number of cycles each block could be guaranteed to be rewritten and how long the data would stay, but datasheets for newer flash are basically all NDA-only and even then you won't get the exact details. At least in that case, I suspect they are trying to hide the inconvenient truth of decreasing reliability; software workarounds can only go so far.
"There are three ways to make a living in this business: be first, be smarter, or cheat." -Margin Call
It feels like the first two are increasingly taken, so businesses are lazily switching to various versions of #3. I don't know where the regulators and punishment for doing that have gone.
I don't understand enough of the technical details in the article - can someone please explain what this means in practice?
I use WD Reds in my Synology NAS in a SHR configuration for daily backups. Should I be worried? Should I replace the disks with other models? What are the risks if I keep the current configuration?
Write performance (particularly random access writes) is degraded because of the way data is written to the disk.
Unfortunately, the nature of RAID means that you can be dealing with a lot of random writes. Further, when a drive fails and you want to replace it, you are pushing massive amounts of writes to the new disk.
A lot of this is due to the Shingling. Like shingles on your roof, the physical locations where data is written overlap. The problem is that if you need to update an already written location, you may also need to update surrounding bits. This is where the random write performance degradation comes from.
If they worked so far, they will continue to work in the future.
With my limited understanding, the new models will fail under intensive work-loads. For example adding them to existing RAID setups to replace a failed drive, where in the beginning they have to be sync-ed and they fail under load after a few hours (either by dropping in performance or not being recognized at all).
They will work reasonable well under lower loads (more common for home NAS setups).
The biggest problem, and what the article is trying to point out, is that Western Digital (and Seagate) are doing all they can to hide this info from customers. They even advertise the HDD as being NAS/RAID friendly, when they are clearly not meant for that type of loads.
Essentially they’re selling disks as “raid compatible”. This implies the disk will perform well under constant pressure: resilvering a raid disk of these sizes can easily take several days.
However, they have cut corners / optimized costs that assumes the drive is not under constant pressure, but rather mostly idle. What this implies is that they likely just have a hybrid magnetic/ssd backend, which is what the outrage is about.
It's not you, the article was written by someone that doesn't understand what they're trying to report on and is repeating facts they've been told are pertinent. Can't blame the reader for being confused.
Isn’t the hard drive space all owned by WD since they bought Seagate? It doesn’t matter as much to their brand because there’s no competition in this area of large platter drives.
Why are they using SMR on small capacity drives? I thought the driving force behind SMR was for higher capacity? I know cheaper 8TB+ drives use SMR.
Is it so they can use fewer platters to get the same capacity, thus reducing the manufacturing cost of the drive? Or is there some other technical reason to do it on low capacity drives?
It should be pretty easy to detect SMR. It's probably sufficient to just compare random read and random write performance and look for a big disparity. Probing for cache size and zone size would be a bit trickier.
Does this mean anything for the Purple line that are specifically for surveillance applications?
My assumption would be that the Purple drives become the default for NAS usage as the surveillance use-case much more closely matches the requirements of a RAID rebuild (a fairly constant write-stream).
My anecdata sample size of 3 has WD Red drives priced very closely to equivalently sized WD Purple drives, with WD Black drives a significant percentage more expensive (40% +).
Does this mean WD Black drives are the last hold-out against SMR for WD brand?
Are the 8TB-14TB drives actually fully cleared? I assume this is all about the official Red (EFAX) line - I own a WD100EMAZ drive (10TB, obtained from an Elements Desktop case) the performance of which has been a little disappointing - I suspect it might be shingled as well.
Resilvering on ZFS in not linear, it is quite some random IO.
A ST8000DM004 is capable of linear reads above 200MB/s, and a normal drive should be able to handle the same speeds with linear writes.
I would not recommend those drives for use with ZFS from my own experience: one of my drives disappeared after 1.5TB of writes while moving a dataset, and only went online again (with a SMART failure) after a power cycle.
It really depends, newer Toshiba and HGST drives in "massive" (ie > 8TB) sizes are almost all 256MB cache for improved in-memory write reordering, but HGST calls out at least some of their drives as not only being PMR but also being better because they're PMR [0] (it's just the most recent one we purchased for our ZFS pool). We haven't had any issues with it (first order of business is writing random values to the disk then reading them back to verify integrity and check SMART values afterwards) and had sustained write speeds the entire time.
"Designed to handle workloads
up to 550TB per year, the Ultrastar DC HC520 is the industry’s first 12TB drive and
uses traditional perpendicular magnetic recording (PMR) technology to make it dropin ready for any enterprise-capacity application or environment."
Based on the reports cited in the article, it looks like earlier models (WDx0EFRX) were not SMR, but newer ones (WDx0EFAX) are, up to 6TB.
Their larger disks are still claimed to be CMR at the moment, though how much credibility anyone should give a WD spokesperson at this point is obviously open to debate.
one way to check, seen on another forum, is to see if the drive reports supporting the TRIM function via smartctl/camcontrol - if it does it's one of these 'DMSMR' style drives
If you think people already knew, why do you expect the stock to go down today? If people already knew, EMH says it was already priced in.
Your point is weak anyway, it is like claiming climate change is false because of today's weather. Stock prices move everyday for many reasons, you can't say bad news had no effect just because the price didn't go down compared to yesterday. It's possible the price would have gone up more without the bad news.
I'm saying I would expect the stock to have performed differently recently as more people found out. I checked and it seemed to behave exactly the same as other stocks.
I'm pretty sure this is a similar
problem to Securities rating agencies in Finance world
Luckily that problem only led to the largest (so far!) recession / crisis humans have seen.
Ok snark over, but we have seen things like this before - take steam boiler production mid to late 19C. This took
insurance companies simply refusing to insure anyone who did not manufacture boilers to their standards to clean up.
Something similar is needed now. Do you know why you cannot claim your covid-19 cancelled holiday from your insurance - because pandemics are not covered by travel insurance - do you know why? Because Re-insurance companies look at the likelihood of pandemics and simply refuse.
I think something different is needed - I think insurance is related to it. Basically we treat government as the insurer of last resort - but we have no real idea of the costs we are shouldering - or the risks we are ignoring.
So what if we had to have obligatory true cost insurance? Buy a house? great is it insured against flooding? Now you built on a flood plain like half of England. Fine your premiums are now twice the cost of your mortgage.
Are you selling crappy products through your business? Great please show business insurance that will make the people you rip off whole. Don't have that insurance? good luck getting anyone to buy off you.
> Because Re-insurance companies look at the likelihood of pandemics and simply refuse.
I believe it's not likelihood alone. It's a combination of very low likelihood, very high cost event that doesn't make it worth it for most.
In the end it likely wasn't the re-insurers decision. They cover pretty much everything for the right price, also pandemics. But no end-customer would've paid the extra price for pandemic coverage so no insurers used it. Unless it's outright illegal I've yet to hear of an event that no insurance company would cover.
A nice example of "ensurers will ensure everything" is the Ansari X Prize (space competition). They ensured against someone actually winning the competition:
> The funding for the US $10,000,000 prize was unconventional in being "backed by an insurance policy to guarantee that the $10 million is in place on the day that the prize is won."
Is this happening on the Red Pro hard drives, their enterprise versions? If not, it sounds like a fairly standard hard drive company marketing move, fine for NAS as long as you use our definition of NAS. Like their megabyte definition change. Disappointing, but not surprising.
You are missing my likely poorly made point, WD seems to have different view of what non-enterprise "NAS use" entails than those users having problems.
While they might have some concept of what home NAS use is, these drives are literally marked as dead by common NAS filesystems/RAID drivers because the filesystem thinks they are malfunctioning due to them being so slow, when they are first put into an array
>keep[s] getting kicked out of RAID arrays due to errors during resilvering
This problem is independent of what type of workload you actually use the NAS for.
See, by NAS HDD they mean "fit for the rapper Nas," so any problems these users have are their fault for not being Nas.
This is hyperbole, but "network attached storage" could basically refer to every hard drive now and not be false advertising. No matter how unacceptable you view this, it's the kind of shit hardware manufacturer's often do.
Not every raid configuration though. Just looked at the Red spec sheet, and it specifically says "without being tested for compatibility with your NAS system, optimum performance is not guaranteed." You'd need to find a setup authorized by their compatibility list that breaks for them to admit any fault.
Only up until the array needs to be rebuilt (eg replacing a drive). At which point the workload is the literal opposite of "bursty with idle time". :(