I was just shopping for an SMR drive for this exact reason. I wanted a backup/archive drive that wasn't going to be used for daily tasks and figured it would be more economical. Because of all the negative associations though, it's hard to actual find drives marketed as SMR, and you see a lot of negative reviews purely for being SMR, so it's hard to get an idea of overall reliability. You really get a sense of how damaging it is when a company is not transparent with their advertising, it kind of ruins the whole market. They should be marketing SMR drives as low cost, high reliability solutions for infrequent write applications.
There are three reasons I would never use an SMR drive in my NAS. 1. Warranty: NAS certified drives typically have warranties of 3 to 5 years compared to their SMR desktop counterparts 2. Robustness: NAS certified means designed to be running 24/7, unlike most desktop SMR drives 3. Cost: SMR Vs NAS CMR drives are so close in price, it's not worth the saving you might make.
Like everything in life, is all down to luck. I still have a 12 year old Synology with the original drives I got at the same time (two blue wd, yes the wrong drive type), and they are still going strong, no bad sectors, and used for secondary backup. For home usage, while the NAS is on 24/7, the drives don't necessarily stay 24/7. Of course adapt to your use case.
In your third point you oppose NAS and SMR drives, but WD Red drives are marketed as NAS drives, and they are SMR. Only WD Red Pro and WD Red Plus drives are CMR. So a buyer really needs to know the products, and check the specs if they want to buy a type of drive or the other. And for the price, the difference is not noticeable or does not make sense. At the time of writing this comment, 4tb Red Plus (CMR) drives are cheaper than Reds (SMR), which are cheaper than Red Pros (CMR) (on Amazon, 120/140/160€)
@@ffordawn676 Thank you for your reply. Yes, you're right. My third point relates to "true" NAS drives, thus ignoring WD Red's which I am aware are SMR. I was referring to CMR drives certified for NAS usage and now realise that some buyers may not be aware that WD Red's are not suitable for NAS's despite their marketing claim. Your last paragraph echoes my own sentiments. NAS certified drives (i.e CMR ones) are so close, or even cheaper, than SMR desktop drives, it's not worth considering an SMR drive under those circumstances for desktop use. Of course, Red Pro, as with Ironwolf Pro, will be more expensive due to their higher specifications.
I have multiple DSMR drives AND 2 NAS boxes - notice I said AND - no SMR IN any of my NAS units! But my regular backups go to DSMR since I use them as "Write occassionally, Read only if theres a distaster" drives. My only issue with DSMR backup is I can only write in 400GB chunks at full speed. Then I need to leave them 5 to 10 mins. If I go to 500GB at full speed, they often disconnect from USB and vanish until they can do thier "reshingle". So long as I remember this, they are best bang for buck available for backup
I was a victim of the WD Red SMR debacle. They replaced them with WD Pros. Got $9/drive (CAD) out of a class action settlement based on misrepresentation of their product.
I believe most of us are using these large cap hard drives for a NAS holding our video collections for Jellyfin / Plex. I guess it works out because it falls into that write once and read many areas. I even imagine videos editors are working off ssds and storing on HHDs... so same case I imagine. Perhaps ill save some money next time and give em a try when bigger caps come out. TY for the info.
Had a NAS with raidz2 and 4x6TB shucked WD drives. Then I found out about the smr issue (and it dawned on me why the price for the drives was so low). It was a nerve wracking exercise to replace the drives one by one with CMR drives, but it worked. Now using the SMR drives in a set-up with two "mirrored" single-drive OMV NAS'es (plus two spare drives). However, got screwed by WD a second time when I bought a new drive that was dead on arrival. The RMA process was a complete mess (and not for free either). I hate that company.
Hello! For my high-capacity NAS systems, I use CMR drives from Seagate and Toshiba. However, since I don't always need access to this data and electricity is expensive, I've started a small experiment. I've installed 4 Seagate ST4000LM024 2.5-inch SMR drives into my old NAS (Synology RS816). They are configured in a SHR array with a redundant disk. The system is mainly used for data synchronization (via Synology Drive), including smaller data such as documents and photos. I've had the system running without any issues for about 3 months now. Of course, regular backups of the system are also taken. I think it can work well if you're not constantly transferring huge amounts of data and don't mix CMR and SMR drives.
If SMR was operated in Host Managed mode (HM-SMR), if the NAS vendors supported it, and if the CMR write cache area they use was of a decent and known size smaller than the typical workload, then they would not be "bad' - the NAS would be able to adjust the load to deal with the peculiarities of the zoned implementation. The problem is that generally speaking none of the above are true outside of enterprise space - the disks are DM-SMR, they hide internal details from the OS and the user - and that makes them a bad idea in a consumer/prosumer NAS outside some very, very specific use cases. A similar issue applies to consumer QLC NAND SSDs, incidentally - the only saving grace is that all-SSD NASes are underpowered right now so the same issue under sustained issue isn't quite as visible as either the NIC bandwith, CPU power or PCIe bandwith is exhausted first, at least for now.
Thanks again, Having a 5 bay RAID 5 NAS, years ago I was not aware that I was using SMR disks. As you explained very well. Raid 5 and SMR are prone to a data disaster. When I became aware of the data risk having SMR drives in a RAID 5 array, I decided to replace them with "normal" drives. The SMR drives were sort of new. I thank WD for giving me the extra costs. For decades I trusted WD to be a reliable partner. Trust comes walking, and goes by horse. Sorry WD.
At the end of the day it's all about having the right tool for the right job, and SMR is just fundamentally unsuited for the kind of constant load that NAS and other multi-drive arrays are put under especially during a rebuild. I still keep that video from Serve the Home in memory when it comes to rebuild games, going from like 17 hours to 9.5 DAYS
I think the "hate" stems from corporate deception and the lack of due diligence. Realistically, SMR drives still, and always will, serve a purpose. For most, the performance and speed is negligible because of the environment and use they reside in. Put it this way... try asking my kids, siblings or parents, if they give a shit whether I install Cat6a or Cat5e. If you know, you know.
As the issue with SMR drives is that writing data to the platter "damages" the the tracks around because of the the shape of the magnetic cells I do not understand why the manufacturers do not use multiple magnetic heads on the same lever arm and track. With 2 heads on the same track head one reads all four tracks the data is modified with new information and written by head two. This means the read modify write is done continuously -eliminating the need for separate rewrites. This is exactly what 3 head tape recorder did in the 90s. Ok, it adds complexity with a second head but its only for reads and it almost completely eliminates the usage differences between SMR and CMR.
Hi, it's been a month but I can answer this question so here goes: What you are describing would require: 1.) Multiple read heads in the cross-track direction--as many as there are shingled tracks in an SMR track "block"--which can be 8 or more. 2.) The same number of write heads, "staggered" so they can each write their overlapping tracks in order... 3.) ...Which also must be positioned far enough behind the read heads for there to be time to process the signals from the read heads before re-writing This would require many readers and writers positioned over a much wider area than usual, necessitating that the "mothership" that flies immediately over the disk surface is also much larger. Why is this a problem? Something people may not appreciate is that the physical spacing (air gap, or helium gap) between the read/write head and the surface of the disk is, nowadays, less than 1 nanometer during drive operation. This is critically important, since both the reading and writing processes have some exponential dependencies on the head-to-disk spacing; if head-disk spacing is relaxed, the achievable capacity of the drive drops very sharply. As such, engineers operate at the very limit of technology to achieve the smallest spacing they can, in all kinds of ways. Furthermore, flying at such a sub-microscopic height requires some very 1.) accurate, and 2.) responsive, control systems. Many different micro and nano-actuators are used to maintain a very small but constant fly-height. The long and short of it is, having a giant mothership with parallel readers and writers would necessarily involve tradeoffs in the head-media spacing. It would not be possible to maintain the absolute minimum spacing for all readers and writers at all tracks at the same time--compromises would have to be made. Granted, this is an engineering limitation, not a fundamental one--you could, in principle, position all the read/write elements perfectly if you had the right magic technology, without violating the laws of physics. But, in practice, whatever spacing you can achieve with e.g. 10 heads, you can always achieve much better with 1 head. And since spacing plays such a critical role in performance, this trade never works in your favor. Another limitation is track-following capability. The whole point of SMR is to increase track density. Today, SMR track pitch can be less than 40 nm. If you want to have a 40nm track pitch, then the servo-mechanical positioning capability of your read/write head needs to be much better than that--generally it is measured in angstroms. Think about that--some $50-100 of mechanical components in a drive have a spatial accuracy on par with a million dollar scanning probe microscope, and about 10-100x better than the smallest feature size achievable with a $300 million EUV lithography tool. If you increased the size and complexity of the reader/writer to accommodate e.g. 10x parallel reads/writes, there would necessarily be compromises in track positioning/following accuracy, which would require you to relax your track pitch, reducing the whole point of SMR in the first place. Remember, SMR only has about a 20% capacity premium over CMR, so there isn't a whole lot of margin to mess things up. These problems both mean that highly parallel read/write (at least in this way) would come at a penalty to overall drive capacity. For tape, this is fine, since they operate at much lower bit density than drives, but over a far greater surface area of media. For a disk drive, what you end up with is a more expensive, lower capacity, and therefore higher $/TB product, but with much better read/write performance. We already have that--it's called an SSD, which no mechanical drive is ever going to compete with in read/write or IOPS, regardless of how parallel your read/write is. So, not only do you need to solve all the engineering problems above (and others...), you need to do it while offering a better value proposition than SSDs. Another problem is that a *lot* of the cost of a drive is in the read/write heads, since those are manufactured using (expensive) semiconductor-like wafer processing technology. If you achieve 4x parallel read/write by using 4x more heads…the value proposition isn’t *that* much better than just having 4x drives-and that’s igonring all the penalties already outlined. So basically, you need to beat the “floor” set by a drive array, while also offering some kind of value proposition relative to the “ceiling” of an SSD. People have looked into it, but it just hasn't worked out (so far…)
It was for this reason i no longer purchase WD Red drives. I used to back and forth between it and Ironwolf depending on pricing. Its now either Ironwolf or enterprise drives. Frustratingly, these drives are often sold in prebuilt nas sets (Non-empty)
What about HSMR? The Exos X14 12TB HSMR is almost half of the price of the CMR, and as far as I have heard, it is shipped as CMR and you need to decide how much SMR to allow (thus the Hybrid in HSMR). It seems to me that even if you lose 2 tb or something like that, the cut in price still makes it a much better deal.
what boggles my mind is. SMR drives arent that much cheaper here. I would love to find some seagate archival but doesnt exist in my market (but seagate does make them).
I have a problem with my single 2TB SMR drive during an incremental backup with OpenZFS, also there I write continuously at the max speed of my network 1Gbps. Sometimes for 10 seconds writing stops and during other periods writing slows down to speeds between 2 and 9MB/s, while in the begin it writes at ~100MB/s. The end result is that my 2nd backup a Pentium 4 HT (3.0GHz) with 4 outdated IDE drives finishes in the same time than the modern SMR drive. The Pentium 4 is limited to a constant 30MB/s by a >90% load on one CPU thread.
Personally I have no issue with SMR drives in theory, especially when adopted for use cases that match how they store data. What bothered me was that manufacturers did not disclose when drives were SMR, and the naming gave no indication. So I don't think they're bad if manufacturers are up-front, and they are used for lighter write situations.
I had a failure in my Synology DS918, with 3 disks WD Red, now after about 5 years I think, took about while to rebuild, I think 3 days, but I do not complain, have an external backup and on Amazon Glacier, so if another disk would have crashed during that time, I still would be ok. But my load at home is not high, like 2-3 times per week I access pictures or empty the camera and edit some. Would be another thing at a place with much higher load as said or higher demand on availability.
Can I ask about your capacity? Was your array mostly full or what when it happened? I have an old Drobo 5n with 5 4TB red drives in it I'm concerned about. It is all backed up to a Synology, since Drobo is now bankrupt. Still I'm curious what I could be in for.
@@MichaelDeHaven Had 3x8 TB and was about half full, running SHR so I inserted a 12 TB and when I have the energy to order 2-3 more, I might go for that. Just thinking if I shall buy a whole new NAS, when it now has 5-6 years of continuous running time. Then I might use that newer drive in that. We’ll see, not a high priority now with kids and loads of other things as well, might as well take a couple of more years as well.
First, the fact that WD kept that information under their hood and not disclose it until really, really late, are very despicable practices. Full stop. Next, it has been proven technically, SMR drives have a significantly performance degradation under certain conditions. As in where the user, for such conditions, has no control over, at all. Only the system has the control. Let's be honest, the only reason SMR drives are still around, is trying to reduce the price(s) for the drives. And, as far I have noticed, such price-differences are minute at best. Technically, SMR can work just fine, but when there are bad conditions, you will notice that you are using SMR, it will take way more time than "usual" to recover from such bad conditions. We have indeed SMR drives with significant run-hours, their failure-rate does seem to be on par with the non-SMR versions. So, I personally would state that SMR is not per say bad, but if possible, should be avoided.
Would you recommend a normal new SMR disc or a refurbished one that is CMR both have a 2 year warranty? Or, for example, for the same price a normal CMR disk of 8tb or a refurbished 12tb for the same price?
Yeah I dont really have a want for SMR, I'd rather go recertified CMR if i need to pinch some pennies. I've used recertified drives a few times and never had any issues. I'm more curious about HAMR drives, and if consumer hardware platforms can currently or will in the future be able to make use of them. Our storage needs as consumers keep growing exponetially, and it's outpacing capacity per bay capabilities. I suppose the immediate solution is just multiple nas units.
In my PCs I have CMR HDDs that are over 15 years old, although they are now very slow they work and do not give smart errors. Now for 2 years I have replaced the older HDDs with Seagate Barracudas and they are SMR, perhaps for this reason noisier? However, 1 of the 2 disks died after a few hours, it was replaced under warranty, now after 2 years these SMR HDDs are already slow and increasingly noisy, so given my experience I don't think I would ever knowingly buy SMR disks for a NAS . To keep a copy of all the data (updated every 6-12 months), however, I don't think there is anything bad or risky in archiving on an SMR HDD (I hope my comment is understandable, I'm not good with languages so I use google translator)
When this hit the news about SMR I checked my unraid server and 3 out of my 5 WD drives were SMR. All ordered with the buy it again option from amazon. How is this possible? Forward ahead 2 years and all 3 of my SMR drives failed in the Array. Only good thing is WD replaced them under warranty. And they sent me three CMR drives as replacements. but I will still never buy Drives from them again.
When you need to rewrite : yes If your drive / array has lots of empty space for swap : should be ok I wonder if it do okay when rebuild because it will just need overwrite everything from start to end and it is not a rewrite which slow on SMR
They make rebuilding take a much longer time when using parity. Replacing a failed CMR with an SMR drive when all other drives are CMR can make a hours long rebuild take days. If they are all SMR the time it takes can quicky get to the "will it ever finish?" state.
What about in the case of Unraid with a cache? That's not raid, and people are generally using a write cache. So writing to the given SMR driven would just happen once a day, all at once, rather than a little bit here and there.
As long as it's tradition UNRAID use and not the recently added ZFS pools, then maybe. It's still a question of how much data in one go vs the cap of the drive (time etc). But yeah, good point
I use SMRs for my plex files as it only gets added to slowly over time and the data isn't critical photos and such. Critical data is stored on regular drives though I'm considering using SMRs to backup the critical data as well. Could be a mistake or could be fine.
Weirdly WD is even pushing "UltraSMR" in their newest Ultrastar lineup. I mean they must think there's a business case there. Even though I have always loved my Ultrastars, for their performance (although quite noisy) and price, compared to NAS drives which is not even a contest, I would never add any kind of SMR drives to my array.
How do you expect the HAMR drives slated for this year to perform in NAS use-cases compared to CMR and SMR? I expect the per-TB cost to be substantially higher, but I'm curious what sort of performance characteristics (speeds, quirks, limitations, etc) might surface.
Should be broadly similar, with the main differences being in cost and reliability. HAMR drives will eventually be offered in both CMR and SMR as well, but you can expect the SMR capacity "uplift" to be smaller for HAMR, at least for awhile.
SMR was a sexy idea. But there is a big flaw in the marketing. They just forgot to sell them for half price or double capacity. A 60 TB SMR drive for the price alf a 30 TB CMR drive could be a thing. Otherwise there is no point to go for SMR.
Yeah, marketing is still very bad. My resentment comes from if I'm looking for a harddrive I have to keep a sheet of model numbers to compare to just to avoid SMR drives because no one makes it clear enough. If they put something in the name like "ARCHIVE" and clearly advertised the slower speed but cheaper capacity, then fine, but they ruined the shopping experience because now you have to dodge these so often. Sellers do not make it any easier, I wanted to get another 2TB Toshiba last year, so I went back to the usual sellers, and so many had the SMR version now that only differs by 1 digit in the model number, but they don't update the listings, and I have to waste so much time confirming "is this the xxx2xxx or xxx1xxx model"? Apart from that one number change, everything is exactly the same (minus the cache size, often its 256, good rule of thumb for quickly sifting through SMRs)
SMR is like tape, is for long term storage, more like archival use: for Banks and other uses where collecting small but constant amounts of data is the day to day. RAID is a back up, 'coz it backs up data. RAID is a waste of HDD and $, 'coz HDDs fail preemptively now and let you save 100% of your data: starts with clicking that lasta like 1 week, before it gets more serious, and still will not lose any data; is an audible warning, no SMART nor Event Viewer in Windows will infor about it yet, until starts losing data, or find damaged sectors, further on, in its failure path. So those that do RAID are wealthy and sophisticated morons
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I was just shopping for an SMR drive for this exact reason. I wanted a backup/archive drive that wasn't going to be used for daily tasks and figured it would be more economical.
Because of all the negative associations though, it's hard to actual find drives marketed as SMR, and you see a lot of negative reviews purely for being SMR, so it's hard to get an idea of overall reliability.
You really get a sense of how damaging it is when a company is not transparent with their advertising, it kind of ruins the whole market.
They should be marketing SMR drives as low cost, high reliability solutions for infrequent write applications.
There are three reasons I would never use an SMR drive in my NAS.
1. Warranty: NAS certified drives typically have warranties of 3 to 5 years compared to their SMR desktop counterparts
2. Robustness: NAS certified means designed to be running 24/7, unlike most desktop SMR drives
3. Cost: SMR Vs NAS CMR drives are so close in price, it's not worth the saving you might make.
Like everything in life, is all down to luck. I still have a 12 year old Synology with the original drives I got at the same time (two blue wd, yes the wrong drive type), and they are still going strong, no bad sectors, and used for secondary backup.
For home usage, while the NAS is on 24/7, the drives don't necessarily stay 24/7. Of course adapt to your use case.
In your third point you oppose NAS and SMR drives, but WD Red drives are marketed as NAS drives, and they are SMR. Only WD Red Pro and WD Red Plus drives are CMR.
So a buyer really needs to know the products, and check the specs if they want to buy a type of drive or the other.
And for the price, the difference is not noticeable or does not make sense. At the time of writing this comment, 4tb Red Plus (CMR) drives are cheaper than Reds (SMR), which are cheaper than Red Pros (CMR) (on Amazon, 120/140/160€)
@@ffordawn676 Thank you for your reply.
Yes, you're right. My third point relates to "true" NAS drives, thus ignoring WD Red's which I am aware are SMR. I was referring to CMR drives certified for NAS usage and now realise that some buyers may not be aware that WD Red's are not suitable for NAS's despite their marketing claim.
Your last paragraph echoes my own sentiments. NAS certified drives (i.e CMR ones) are so close, or even cheaper, than SMR desktop drives, it's not worth considering an SMR drive under those circumstances for desktop use. Of course, Red Pro, as with Ironwolf Pro, will be more expensive due to their higher specifications.
SMR ones may be bad but not ASMR
*rubs finger and thumb against each other, over and over again, 1 inch from my ear* ...yeah....
I can see it now.... @nascompares dumming his fingers across a DS923+ while whispering "s-y-n-o-l-o-g-y.....Disk-station....." 😅
I have multiple DSMR drives AND 2 NAS boxes - notice I said AND - no SMR IN any of my NAS units!
But my regular backups go to DSMR since I use them as "Write occassionally, Read only if theres a distaster" drives.
My only issue with DSMR backup is I can only write in 400GB chunks at full speed. Then I need to leave them 5 to 10 mins.
If I go to 500GB at full speed, they often disconnect from USB and vanish until they can do thier "reshingle".
So long as I remember this, they are best bang for buck available for backup
Each time I see your videos I am Impressed of the big pile of NAS systems on the left side of your table.
I was a victim of the WD Red SMR debacle. They replaced them with WD Pros. Got $9/drive (CAD) out of a class action settlement based on misrepresentation of their product.
I believe most of us are using these large cap hard drives for a NAS holding our video collections for Jellyfin / Plex. I guess it works out because it falls into that write once and read many areas. I even imagine videos editors are working off ssds and storing on HHDs... so same case I imagine. Perhaps ill save some money next time and give em a try when bigger caps come out. TY for the info.
Had a NAS with raidz2 and 4x6TB shucked WD drives. Then I found out about the smr issue (and it dawned on me why the price for the drives was so low). It was a nerve wracking exercise to replace the drives one by one with CMR drives, but it worked. Now using the SMR drives in a set-up with two "mirrored" single-drive OMV NAS'es (plus two spare drives). However, got screwed by WD a second time when I bought a new drive that was dead on arrival. The RMA process was a complete mess (and not for free either). I hate that company.
Hello! For my high-capacity NAS systems, I use CMR drives from Seagate and Toshiba. However, since I don't always need access to this data and electricity is expensive, I've started a small experiment. I've installed 4 Seagate ST4000LM024 2.5-inch SMR drives into my old NAS (Synology RS816). They are configured in a SHR array with a redundant disk. The system is mainly used for data synchronization (via Synology Drive), including smaller data such as documents and photos. I've had the system running without any issues for about 3 months now. Of course, regular backups of the system are also taken. I think it can work well if you're not constantly transferring huge amounts of data and don't mix CMR and SMR drives.
If SMR was operated in Host Managed mode (HM-SMR), if the NAS vendors supported it, and if the CMR write cache area they use was of a decent and known size smaller than the typical workload, then they would not be "bad' - the NAS would be able to adjust the load to deal with the peculiarities of the zoned implementation. The problem is that generally speaking none of the above are true outside of enterprise space - the disks are DM-SMR, they hide internal details from the OS and the user - and that makes them a bad idea in a consumer/prosumer NAS outside some very, very specific use cases.
A similar issue applies to consumer QLC NAND SSDs, incidentally - the only saving grace is that all-SSD NASes are underpowered right now so the same issue under sustained issue isn't quite as visible as either the NIC bandwith, CPU power or PCIe bandwith is exhausted first, at least for now.
Thanks again,
Having a 5 bay RAID 5 NAS, years ago I was not aware that I was using SMR disks.
As you explained very well. Raid 5 and SMR are prone to a data disaster.
When I became aware of the data risk having SMR drives in a RAID 5 array, I decided to replace them with "normal" drives.
The SMR drives were sort of new. I thank WD for giving me the extra costs.
For decades I trusted WD to be a reliable partner.
Trust comes walking, and goes by horse. Sorry WD.
At the end of the day it's all about having the right tool for the right job, and SMR is just fundamentally unsuited for the kind of constant load that NAS and other multi-drive arrays are put under especially during a rebuild. I still keep that video from Serve the Home in memory when it comes to rebuild games, going from like 17 hours to 9.5 DAYS
I think the "hate" stems from corporate deception and the lack of due diligence. Realistically, SMR drives still, and always will, serve a purpose. For most, the performance and speed is negligible because of the environment and use they reside in. Put it this way... try asking my kids, siblings or parents, if they give a shit whether I install Cat6a or Cat5e. If you know, you know.
I got burned once by an SMR drive, never again!
As the issue with SMR drives is that writing data to the platter "damages" the the tracks around because of the the shape of the magnetic cells I do not understand why the manufacturers do not use multiple magnetic heads on the same lever arm and track.
With 2 heads on the same track head one reads all four tracks the data is modified with new information and written by head two. This means the read modify write is done continuously -eliminating the need for separate rewrites. This is exactly what 3 head tape recorder did in the 90s.
Ok, it adds complexity with a second head but its only for reads and it almost completely eliminates the usage differences between SMR and CMR.
Hi, it's been a month but I can answer this question so here goes:
What you are describing would require:
1.) Multiple read heads in the cross-track direction--as many as there are shingled tracks in an SMR track "block"--which can be 8 or more.
2.) The same number of write heads, "staggered" so they can each write their overlapping tracks in order...
3.) ...Which also must be positioned far enough behind the read heads for there to be time to process the signals from the read heads before re-writing
This would require many readers and writers positioned over a much wider area than usual, necessitating that the "mothership" that flies immediately over the disk surface is also much larger.
Why is this a problem?
Something people may not appreciate is that the physical spacing (air gap, or helium gap) between the read/write head and the surface of the disk is, nowadays, less than 1 nanometer during drive operation. This is critically important, since both the reading and writing processes have some exponential dependencies on the head-to-disk spacing; if head-disk spacing is relaxed, the achievable capacity of the drive drops very sharply. As such, engineers operate at the very limit of technology to achieve the smallest spacing they can, in all kinds of ways.
Furthermore, flying at such a sub-microscopic height requires some very 1.) accurate, and 2.) responsive, control systems. Many different micro and nano-actuators are used to maintain a very small but constant fly-height.
The long and short of it is, having a giant mothership with parallel readers and writers would necessarily involve tradeoffs in the head-media spacing. It would not be possible to maintain the absolute minimum spacing for all readers and writers at all tracks at the same time--compromises would have to be made. Granted, this is an engineering limitation, not a fundamental one--you could, in principle, position all the read/write elements perfectly if you had the right magic technology, without violating the laws of physics. But, in practice, whatever spacing you can achieve with e.g. 10 heads, you can always achieve much better with 1 head. And since spacing plays such a critical role in performance, this trade never works in your favor.
Another limitation is track-following capability. The whole point of SMR is to increase track density. Today, SMR track pitch can be less than 40 nm. If you want to have a 40nm track pitch, then the servo-mechanical positioning capability of your read/write head needs to be much better than that--generally it is measured in angstroms. Think about that--some $50-100 of mechanical components in a drive have a spatial accuracy on par with a million dollar scanning probe microscope, and about 10-100x better than the smallest feature size achievable with a $300 million EUV lithography tool. If you increased the size and complexity of the reader/writer to accommodate e.g. 10x parallel reads/writes, there would necessarily be compromises in track positioning/following accuracy, which would require you to relax your track pitch, reducing the whole point of SMR in the first place. Remember, SMR only has about a 20% capacity premium over CMR, so there isn't a whole lot of margin to mess things up.
These problems both mean that highly parallel read/write (at least in this way) would come at a penalty to overall drive capacity. For tape, this is fine, since they operate at much lower bit density than drives, but over a far greater surface area of media. For a disk drive, what you end up with is a more expensive, lower capacity, and therefore higher $/TB product, but with much better read/write performance. We already have that--it's called an SSD, which no mechanical drive is ever going to compete with in read/write or IOPS, regardless of how parallel your read/write is. So, not only do you need to solve all the engineering problems above (and others...), you need to do it while offering a better value proposition than SSDs.
Another problem is that a *lot* of the cost of a drive is in the read/write heads, since those are manufactured using (expensive) semiconductor-like wafer processing technology. If you achieve 4x parallel read/write by using 4x more heads…the value proposition isn’t *that* much better than just having 4x drives-and that’s igonring all the penalties already outlined. So basically, you need to beat the “floor” set by a drive array, while also offering some kind of value proposition relative to the “ceiling” of an SSD.
People have looked into it, but it just hasn't worked out (so far…)
Pretty sure: interference and heads take space (so you cannot have several of them extremely close together)
It was for this reason i no longer purchase WD Red drives. I used to back and forth between it and Ironwolf depending on pricing. Its now either Ironwolf or enterprise drives.
Frustratingly, these drives are often sold in prebuilt nas sets (Non-empty)
Good job on transitions and chapter title cards by the way
Bought a WD-Black 8tb new for 176.00 in external box with fan… great drive! Getting good speeds for a HDD… its probably SMR
I use SMRs in my NAS for 6-7 years now, it works like charm with some NVMe cache ... but hiding specs from customer is bad ....
What about HSMR? The Exos X14 12TB HSMR is almost half of the price of the CMR, and as far as I have heard, it is shipped as CMR and you need to decide how much SMR to allow (thus the Hybrid in HSMR). It seems to me that even if you lose 2 tb or something like that, the cut in price still makes it a much better deal.
Thank you for this vid. How I'll avoid SMR drives as performance and longevity are my concern.
Thank you. Happy Sunday.
what boggles my mind is. SMR drives arent that much cheaper here. I would love to find some seagate archival but doesnt exist in my market (but seagate does make them).
I have a problem with my single 2TB SMR drive during an incremental backup with OpenZFS, also there I write continuously at the max speed of my network 1Gbps. Sometimes for 10 seconds writing stops and during other periods writing slows down to speeds between 2 and 9MB/s, while in the begin it writes at ~100MB/s. The end result is that my 2nd backup a Pentium 4 HT (3.0GHz) with 4 outdated IDE drives finishes in the same time than the modern SMR drive. The Pentium 4 is limited to a constant 30MB/s by a >90% load on one CPU thread.
Personally I have no issue with SMR drives in theory, especially when adopted for use cases that match how they store data. What bothered me was that manufacturers did not disclose when drives were SMR, and the naming gave no indication. So I don't think they're bad if manufacturers are up-front, and they are used for lighter write situations.
i appreciate your explanation!
I think I have 1 WD SMR Drive on my ZFS Mirror, I have 4 drive (2 drive each VDEV, with total 2 VDEV), and one of them is WD, which totally smell SMR
I had a failure in my Synology DS918, with 3 disks WD Red, now after about 5 years I think, took about while to rebuild, I think 3 days, but I do not complain, have an external backup and on Amazon Glacier, so if another disk would have crashed during that time, I still would be ok. But my load at home is not high, like 2-3 times per week I access pictures or empty the camera and edit some. Would be another thing at a place with much higher load as said or higher demand on availability.
Can I ask about your capacity? Was your array mostly full or what when it happened? I have an old Drobo 5n with 5 4TB red drives in it I'm concerned about. It is all backed up to a Synology, since Drobo is now bankrupt. Still I'm curious what I could be in for.
@@MichaelDeHaven Had 3x8 TB and was about half full, running SHR so I inserted a 12 TB and when I have the energy to order 2-3 more, I might go for that. Just thinking if I shall buy a whole new NAS, when it now has 5-6 years of continuous running time. Then I might use that newer drive in that. We’ll see, not a high priority now with kids and loads of other things as well, might as well take a couple of more years as well.
First, the fact that WD kept that information under their hood and not disclose it until really, really late, are very despicable practices. Full stop.
Next, it has been proven technically, SMR drives have a significantly performance degradation under certain conditions.
As in where the user, for such conditions, has no control over, at all. Only the system has the control.
Let's be honest, the only reason SMR drives are still around, is trying to reduce the price(s) for the drives.
And, as far I have noticed, such price-differences are minute at best.
Technically, SMR can work just fine, but when there are bad conditions, you will notice that you are using SMR, it will take way more time than "usual" to recover from such bad conditions.
We have indeed SMR drives with significant run-hours, their failure-rate does seem to be on par with the non-SMR versions.
So, I personally would state that SMR is not per say bad, but if possible, should be avoided.
Would you recommend a normal new SMR disc or a refurbished one that is CMR both have a 2 year warranty?
Or, for example, for the same price a normal CMR disk of 8tb or a refurbished 12tb for the same price?
Yeah I dont really have a want for SMR, I'd rather go recertified CMR if i need to pinch some pennies. I've used recertified drives a few times and never had any issues. I'm more curious about HAMR drives, and if consumer hardware platforms can currently or will in the future be able to make use of them. Our storage needs as consumers keep growing exponetially, and it's outpacing capacity per bay capabilities. I suppose the immediate solution is just multiple nas units.
In my PCs I have CMR HDDs that are over 15 years old, although they are now very slow they work and do not give smart errors.
Now for 2 years I have replaced the older HDDs with Seagate Barracudas and they are SMR, perhaps for this reason noisier?
However, 1 of the 2 disks died after a few hours, it was replaced under warranty, now after 2 years these SMR HDDs are already slow and increasingly noisy, so given my experience I don't think I would ever knowingly buy SMR disks for a NAS .
To keep a copy of all the data (updated every 6-12 months), however, I don't think there is anything bad or risky in archiving on an SMR HDD
(I hope my comment is understandable, I'm not good with languages so I use google translator)
When this hit the news about SMR I checked my unraid server and 3 out of my 5 WD drives were SMR. All ordered with the buy it again option from amazon. How is this possible? Forward ahead 2 years and all 3 of my SMR drives failed in the Array. Only good thing is WD replaced them under warranty. And they sent me three CMR drives as replacements. but I will still never buy Drives from them again.
When you need to rewrite : yes
If your drive / array has lots of empty space for swap : should be ok
I wonder if it do okay when rebuild because it will just need overwrite everything from start to end and it is not a rewrite which slow on SMR
They make rebuilding take a much longer time when using parity. Replacing a failed CMR with an SMR drive when all other drives are CMR can make a hours long rebuild take days. If they are all SMR the time it takes can quicky get to the "will it ever finish?" state.
@@unicaller1 gosh , this one makes the array bit dangerous as during rebuilding it have less / no protection
I Better stick with CMR then
@@frankwong9486 Yea, it really is a great technology just not appropriate for all uses.
Cmr for commercial use… SMR for every one else..
What about in the case of Unraid with a cache? That's not raid, and people are generally using a write cache. So writing to the given SMR driven would just happen once a day, all at once, rather than a little bit here and there.
As long as it's tradition UNRAID use and not the recently added ZFS pools, then maybe. It's still a question of how much data in one go vs the cap of the drive (time etc). But yeah, good point
I use SMRs for my plex files as it only gets added to slowly over time and the data isn't critical photos and such. Critical data is stored on regular drives though I'm considering using SMRs to backup the critical data as well. Could be a mistake or could be fine.
SMR should be illegal.
Do you have any news about what's gonna come out at the Synology's event of the 21st? Any new devices?
What's a "price point"? You mean price?
I really appreciate all your videos, I have learned a lot and you have converted me to an acolyte of the Holy Church of the NAS-areth.
Weirdly WD is even pushing "UltraSMR" in their newest Ultrastar lineup. I mean they must think there's a business case there.
Even though I have always loved my Ultrastars, for their performance (although quite noisy) and price, compared to NAS drives which is not even a contest, I would never add any kind of SMR drives to my array.
How do you expect the HAMR drives slated for this year to perform in NAS use-cases compared to CMR and SMR? I expect the per-TB cost to be substantially higher, but I'm curious what sort of performance characteristics (speeds, quirks, limitations, etc) might surface.
Should be broadly similar, with the main differences being in cost and reliability. HAMR drives will eventually be offered in both CMR and SMR as well, but you can expect the SMR capacity "uplift" to be smaller for HAMR, at least for awhile.
SMR was a sexy idea. But there is a big flaw in the marketing. They just forgot to sell them for half price or double capacity. A 60 TB SMR drive for the price alf a 30 TB CMR drive could be a thing. Otherwise there is no point to go for SMR.
Yeah, marketing is still very bad. My resentment comes from if I'm looking for a harddrive I have to keep a sheet of model numbers to compare to just to avoid SMR drives because no one makes it clear enough. If they put something in the name like "ARCHIVE" and clearly advertised the slower speed but cheaper capacity, then fine, but they ruined the shopping experience because now you have to dodge these so often.
Sellers do not make it any easier, I wanted to get another 2TB Toshiba last year, so I went back to the usual sellers, and so many had the SMR version now that only differs by 1 digit in the model number, but they don't update the listings, and I have to waste so much time confirming "is this the xxx2xxx or xxx1xxx model"? Apart from that one number change, everything is exactly the same (minus the cache size, often its 256, good rule of thumb for quickly sifting through SMRs)
btrfs writes data to HDDs in a way that actually makes it suitable for SMR's physical writing method so performance on them is pretty good actually.
Here I was thinking to myself why tf ASMR is bad?
SMR is like tape, is for long term storage, more like archival use: for Banks and other uses where collecting small but constant amounts of data is the day to day.
RAID is a back up, 'coz it backs up data. RAID is a waste of HDD and $, 'coz HDDs fail preemptively now and let you save 100% of your data: starts with clicking that lasta like 1 week, before it gets more serious, and still will not lose any data; is an audible warning, no SMART nor Event Viewer in Windows will infor about it yet, until starts losing data, or find damaged sectors, further on, in its failure path. So those that do RAID are wealthy and sophisticated morons