[HN Gopher] Micron rolls out 276-layer SSD trio for speed, scale...
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Micron rolls out 276-layer SSD trio for speed, scale, and stability
Author : rbanffy
Score : 123 points
Date : 2025-07-30 21:54 UTC (4 days ago)
(HTM) web link (blocksandfiles.com)
(TXT) w3m dump (blocksandfiles.com)
| ggm wrote:
| I purchased 2TB ssd for a home nas. I watched prices for 18
| months. They didn't move an inch.
|
| Prices for HDD do drop when the TB available rises but there
| seems to be a "floor" price.
|
| For SSD, there definitely appears to be a floor price.
|
| I am pretty convinced this is not cost btw. This is classic
| cost/price disjoint stuff.
|
| The price is tracking people's willingness to pay.
| wmf wrote:
| The floor for hard disks is the cost of the case, motor,
| controller board, etc. The floor for SSDs is the controller and
| the PCB.
| dopa42365 wrote:
| Price/TB is nearly identical for ancient SATA and new "high-
| end" PCIe 4 M.2 SSDs. The cost is EVERYTHING except the
| controller and the PCB. Which would be the memory,
| shockingly.
| ggm wrote:
| Do you think they have a yield problem? The price on chips
| usually drops when the production tech matures. I could
| believe the fab lines are running smoking hot, but surely
| by now lower density fab in all kinds of economies could be
| making this tech.
| esseph wrote:
| Maybe spending time making more GPU memory instead?
| wtallis wrote:
| DRAM and NAND require entirely different fabs.
| ggm wrote:
| We're nowhere near floor cost in SSD because the cost of the
| PCB and controller is cents.
|
| We're not even tracking the chipcost for the storage. There's
| no linear function between them in terms of numbers, or die
| space.
|
| The price is just "the price"
| elchananHaas wrote:
| Not true. High end controllers need DRAM for caching
| indexes. That's at least a few dollars.
|
| Flash storage is a commodity, we are paying close to the
| amortized cost of manufactured and sales.
| ggm wrote:
| Mate, if you think we're paying amortised costs you
| either work in American pharma or marketing. We're paying
| fat shareholder returns.
|
| "A few dollars" forsooth. My 2TB SSD cost $150 AUD and
| was (I believe) immensely profitable to everyone down the
| supply chain. The same spend gets you 16GB of packaged
| DDR ram and I think we can both see there is no linear
| relationship between the DDR chip cost, in GB and the
| 100x denser storage needed for SLC flash. This is not
| about vlsi density or number of chips. I'm not paying
| $15,000 more for my SSD.
|
| "The prices are the prices"
| fh973 wrote:
| An SSD with 2TB flash typically contains 2GB RAM for
| lookup tables.
| AtlasBarfed wrote:
| We are talking about Samsung and Micron here?
| HarHarVeryFunny wrote:
| The cost of manufacturing a 276 layer (!!!) NAND chip must
| also be significant, and a I dare say takes longer than the
| mechanical components given that we're talking 276 sequential
| steps of applying photo resist, UV exposure, then etching ...
| wtallis wrote:
| The whole reason why 3D NAND happened and higher layer
| counts enable cheaper, higher density storage is that it
| _doesn 't_ require an etch step per layer to build the
| memory cells. It's just deposit several dozen layers then
| etch holes down through all of those layers in one step,
| followed by filling in those holes with different
| materials. (Though at 276 layers, it's a stack of more than
| one deck of layers built as separate batches. The aspect
| ratio of the holes is the limiting factor.)
|
| But aside from that, the cost of the NAND is the _variable_
| portion of the drive 's cost, not part of the fixed floor
| of cost necessary for a drive of any capacity.
| HarHarVeryFunny wrote:
| Interesting - thanks. I wasn't aware 3D NAND was built
| multiple layers at a time in this way.
|
| How are the layers made different, without individual
| masking and etch?
| wtallis wrote:
| The layers largely _aren 't_ different. The end result is
| a vertical string of (theoretically identical) NAND
| memory cells filling the holes that were etched through
| the stack, with contacts at the top and bottom. At the
| edge of the stack, at the end of the fabrication process,
| they etch a staircase to expose one contact with each
| layer. See https://thememoryguy.com/3d-nand-how-do-you-
| access-the-contr...
| Dylan16807 wrote:
| SSD prices cratered in 2023, then shot way back up, and have
| barely dropped since then.
|
| Baseline name brand SSDs got down to about $75 for 2TB, and I'm
| not going to be impressed by anything until I see similar
| numbers again.
| porphyra wrote:
| I got an Intel 660P 2TB for $55 haha. Should have stocked up
| on bigger SSDs ugh.
| adastra22 wrote:
| Also the capacities for SSDs have barely budged. Many years ago
| I went all-out and equipped my PC with a 4TB SSD. Just last
| week I went SSD shopping for the first time in ages.. and 4TB
| was the largest drive anyone had. It's a few generations later
| and the new NVME/PCIe standards mean faster, lower-latency
| drives. But where are the 8TB, 12TB, or 24TB drives?
| Dylan16807 wrote:
| There's a couple 8TB options, but with the twin constraints
| of M.2 size and price nobody is really bothering to go bigger
| for consumer parts.
|
| And the technologies for fast connections to 2.5" drives keep
| failing to get a foothold in consumer products.
| crote wrote:
| > And the technologies for fast connections to 2.5" drives
| keep failing to get a foothold in consumer products.
|
| Not surprising, considering the _vast_ majority of
| consumers don 't need more storage than you can easily fit
| in an M.2 form factor. Why mess around with expensive
| enterprise U.2 drives when it gives you zero benefit and
| gains you the hassle of dealing with extra wires and
| finding space for an ugly bulky rectangle?
|
| Once you get to storage sizes where 2.5" becomes a need,
| you are well beyond the consumer price range. Very few
| people are willing to spend more on a single SSD than on
| the rest of their gaming computer combined.
| mort96 wrote:
| With individual games being hundreds of gigabytes and
| growing, I'm not convinced that you're right.
| Tadpole9181 wrote:
| The "vast majority of consumers" are not PC gamers who
| keep a dozen AAA games installed at a time. They have
| work PCs and laptops.
| mort96 wrote:
| I never said that the vast majority of people need large
| SSDs.
|
| I said that the set of people who need large SSDs is big
| enough such that its complement does not necessarily
| constitute the "vast majority".
|
| Obviously what you mean by "vast majority" is somewhat
| subjective, and there is absolutely room to disagree with
| my statement. But argue against the right thing.
| wtallis wrote:
| 4TB is what currently fits _easily_ into the M.2 form
| factor, and 8TB has been _possible_ for years without
| much extra expense in custom packaging. I 'm quite
| confident that it is fair to say the "vast majority" of
| consumers _do not need_ 8TB or more of storage in their
| laptops.
| taraindara wrote:
| If local storage becomes too cheap, how can companies
| push their cloud storage subscriptions? Imho it's sad
| that ssds haven't gotten much bigger. A spinning disk can
| now house dozens of tb. If 8tb can fit on an m.2, it
| could feasibly fit even more into an SSD form factor. Not
| as fast as nvme, but still faster and somewhat more
| resilient than hdds. I have a strong desire for ssds like
| this... but my only option is super expensive u.2, and I
| don't need it to be that crazy fast. Just faster and
| smaller than hdd would suffice
| mort96 wrote:
| It pains me so much. I would love a laptop with a 4TB or
| 8TB SSD. But the 3.5 extra TB to go from a 0.5TB SSD to a
| 4TB SSD costs _1758 USD_ if I want an Apple laptop (which
| I do, for all sorts of other reasons). It 's absolutely
| wild.
| radicality wrote:
| They exist but definitely more painful to use at a home setup
| since their formats are more server oriented, like U.2/U.3 or
| E1S and few others. And for course the prices - you can get
| 30,60 TB (and even more), but it's gonna be >$4k.
|
| And versus the normal M2 drives, the larger server grade are
| more annoying. For example, I got recently a 15.36TB Kioxia
| Cd6-R in U.3 format, for $1.3k, which is not bad for ssd
| prices. After getting the right adapters and fitting it
| inside a minisforum ms-01. It's working fine, but it
| immediately reached its "critical" temperature (while doing
| nothing) so I had to attach a big fan and cool it. All the
| larger SSDs which are meant for server rooms will expect lots
| of cooling.
|
| https://www.serversupply.com/SSD/PCI-E4.0/15.36TB/KIOXIA/KCD.
| ..
| adastra22 wrote:
| Why not get 4x 4TB drives and stripe?
| LtdJorge wrote:
| MS-01 doesn't have enough space
| bbarnett wrote:
| I agree this would work, and yes backups are important,
| but you're now at 1/4 reliability plus raid issues
| reliability.
|
| The upthread may be able to hug that, but I like a quiet
| night in, not an unreliable wildcat.
| cm2187 wrote:
| RAID 0, ok (but that's a bit dangerous). As soon as you
| add some redundancy, you pay either a massive price in
| term of capacity or in term of performance, pretty much
| any implementation you look at (ZFS, MD, Windows storage
| space, etc). Larger SSDs means less components which can
| fail, less power consumption per TB.
| consp wrote:
| You can also look up the rated idle power in the datasheets
| to know beforehand. Anything over ~5w needs cooling and
| usually they are 10+w (at least the ten or so I have here
| at home). Some of my disks have a low power more (still 7w)
| which you can enable with vendor tooling or the correct sas
| command but ymmv. Check the datasheet, it almost always
| states max 45c ambient and continuous airflow required.
| Culonavirus wrote:
| I mean, isn't it obvious? There is no demand for massive
| SSDs. The current "average consumer" capacity has stabilized
| at 1-2TB for a system drive. It's also what you buy for your
| PS5s etc. There's just not that many (popular) use cases for
| larger SSD. Even with gaming, which is probably the most
| widespread use case for "fast and big" drives, people found
| out that there's only so many AAA 150GB behemoths that they
| can play at the same time...
| bravesoul2 wrote:
| photo and video use case?
| zozbot234 wrote:
| As an average consumer/data hoarder, why not store those
| on cheap spinning HDD's? They can stream the data fast
| enough, and modern NAS hardware gives you easy RAID too.
| You don't really need super-quick random access to
| multiple TB's of data, so HDD storage is probably good
| enough.
| daymanstep wrote:
| HDD is really not fast enough if you're going to be doing
| a RAID rebuild with a 18TB HDD
| GauntletWizard wrote:
| It's plenty fast enough for my N+2 ZFS Raid, but I'll
| admit that that time is still measured in days.
| lostlogin wrote:
| I'm running several that large or larger in a Synology.
|
| Adding a drive takes a week. Replacing a drive a slightly
| quicker, but rebuild times are no joke.
| Uvix wrote:
| I think you're confusing cause and effect - 1-2 TB is the
| most common for PS5s because it's still where the price-
| per-GB sweet spot is. I bought a 2 TB because it was the
| cheapest per GB at the time, figuring I'd come out ahead
| financially even if I replaced it with a 4 TB in 2-3 years.
|
| Alas, prices have not come down like I expected. And sure,
| there's only so many I can play at a time, but I also don't
| want to have to wait through a reinstall each time I change
| it up.
| mjevans wrote:
| If consumers were offered the same space for half the cost
| or same cost for double the space, I find it likely at
| least 30% would pick each of those bins.
|
| It's not that people don't want larger drives, it really is
| that this is what the market is willing to bear and there
| is NOT sufficient competition to keep prices low.
| lostlogin wrote:
| > There is no demand for massive SSDs.
|
| Then why can I buy 22TB spinner by disks so easily?
|
| I'd love to go solid state, but the cost should be
| phenomenal.
|
| Judging by comments here, the server options also require a
| lot of cooling, and keeping the noise down is the point for
| me (along with keeping heat + power down, and speed).
| userbinator wrote:
| The 22TB HDDs are good for archival and long-term
| storage.
| justinclift wrote:
| The capacities for SSDs have barely budged in the consumer
| space, but they're going upwards a lot for enterprise and 2nd
| hand enterprise drives.
|
| ie: https://www.ebay.com/itm/186355513308
|
| There are heaps on Ebay, but you'll be paying $$ for the
| larger sized drives.
| mananaysiempre wrote:
| There are 8TB drives, and (ignoring QLC ones) 18 months ago
| you'd have paid over $1200 for either of the two models
| available (Sabrent Rocket 4 Plus or Inland Performance Plus).
| Then WD released a 8TB version of their SN850X at an initial
| price of $850. These days I regularly see it for $650 or
| below (Amazon actually has it for $600 right this moment),
| which is a positive but tolerable premium over buying 2x4TB
| of the same (admittedly high-end) model. The other two
| options have also come down in price, though the Sabrent
| still hovers just below a thousand.
| justinclift wrote:
| Be extremely careful of buying WD (NVMe) SSDs if you're
| intending on using them with Linux:
| https://github.com/openzfs/zfs/discussions/14793
|
| Many _serious_ reports of problems there, across many
| models and firmware revisions. It's an ongoing problem, and
| WD is ignoring it entirely.
| jeffbee wrote:
| It's just a brand. The SN770 shares nothing technical
| with, for example, the SN8100.
| justinclift wrote:
| Well, "the brand" is ignoring the problems across several
| SSD models.
| wtallis wrote:
| The reports in that thread you linked to are clustered
| around several models that _do_ have substantial shared
| technology: a DRAMless design using an in-house SanDisk
| controller, and difficulties arise with the NVMe Host
| Memory Buffer feature that is only applicable to DRAMless
| drives. But the high-end SanDisk drives _aren 't_
| DRAMless, and the SN8100 in particular doesn't even use
| an in-house SanDisk controller.
| mananaysiempre wrote:
| Thanks! I see that the people reporting problems with the
| (DRAMless) SN770 there also report no problems with the
| SN850X, but that might not be indicative either way--
| AFAIU the 8TB SN850X has somewhat different internals
| compared to its lower-capacity brethren. (It does put
| Framework's decision to ship SN770--now SN7100--SSDs in
| their laptops as standard in an unfavourable light.)
| mschuster91 wrote:
| > But where are the 8TB, 12TB, or 24TB drives?
|
| Kioxia has them for servers [1]. You'll pay for that
| privilege though, 12.8 TB will set you back a healthy 1.600
| EUR [2] and 30 TB 4.100 EUR [2].
|
| [1] https://europe.kioxia.com/de-de/business/ssd/enterprise-
| ssd....
|
| [2] https://www.primeline-solutions.com/de/kioxia-12-8-tb-
| cd8-v-...
|
| [3] https://www.primeline-solutions.com/de/kioxia-30-72-tb-
| cm7-r...
| abdullahkhalids wrote:
| Why do you think the price of SSDs should be close to cost?
|
| As there are many consumer level producers (who all buy from a
| smaller set of actual producers), it may seem like the market
| is close to perfect competition (which would justify
| price=cost).
|
| But actually there are many low quality producers that
| frequently burn those stupid enough to buy from them. And a few
| high quality producers who generally sell what they advertise.
| So if you are trying to buy a high quality SSD, you are buying
| from an oligopoly that have built their brands over the years.
| So they can charge significantly higher than cost due to this
| reason.
|
| And I imagine that others can't drop their prices much lower
| than this price because then people get suspicious and don't
| buy it at all.
| ggm wrote:
| > Why do you think the price of SSDs should be close to cost?
|
| Not close, but closeER and at least some evidence of
| tracking. That's what I'd expect if they were ubiquitous.
|
| Some goods track commodity prices closely. Shrinkflation
| happens when you can't easily alter the unit price, chocolate
| bars are a good example. Not that we pay anything like as
| little as the producers get: there's enough competition that
| putting valhrona to one side, chocolate prices reflect
| commodity prices. Same with fuel. Same with ROHC compliant
| resistors. SMD components. PCBs. Batteries, led light bulbs.
| DDR memory.
|
| Not SSD. There is no reason it must, this isn't the laws of
| physics. I just observe it doesn't. If there was more visible
| competition in supply of inputs, they MIGHT. But it looks
| like at best a duopoly or tri-opoly of inputs, and prices
| reflect demand a lot more. Supply isn't even close to demand,
| there's no surplus.
|
| Those other things are somewhat peripheral. Not saying they
| don't have a role, but I don't think it's fundamental. I
| bought 6 "patriot" P210 and they get average to poor reviews
| for speed and reliability.
| lazide wrote:
| Eh, probably RAM'esque price fixing. Not that anyone is
| going to look too closely with all the geopolitical fuckery
| right now.
| mananaysiempre wrote:
| There _have_ been reports that Micron has been doing
| unusual ammounts of lobbying around the time that the US
| government introduced trade sanctions against YMTC and
| Apple dropped their plans to start using them. (Though
| that time period also coincides with the CHIPS Act
| frenzy, so take with a grain of salt.)
| kijin wrote:
| There is no consumer market for 4TB+ SSDs. There never was, and
| there probably won't be for the foreseeable future. Most non-
| technical people have been conditioned to store their data on
| their phones and/or in the cloud these days. When they need
| more storage, their first thought is to upgrade their cloud
| plan, not to open up their device and void the warranty.
|
| Professionals like us know of course that the SSD is an easily
| upgradable component. But we also tend to know how to set up a
| NAS with 4x 18TB HDDs in a zfs pool that can saturate the
| bandwidth of any reasonable home network when transferring
| large files. So the market for professionals and enthusiasts
| don't always translate into a market for large SSDs.
| dontlaugh wrote:
| I would like to be able to get rid of my hard drive NAS at
| some point, in favour of something smaller and quieter. The
| price really doesn't make sense right now, though.
| rbanffy wrote:
| > and there probably won't be for the foreseeable future.
|
| There might be if we get to vert large models that rely more
| on storage than compute, but that's a lot of "ifs" in there.
| Maybe when people start capturing their birthdays in 16K HDR
| at 120 fps.
| asnyder wrote:
| Opening up one's device does not void the warranty in the US.
| We have the Magnuson-Moss Warranty Act which forbids this,
| despite manufactures trying to groom us otherwise with those
| void if removed or broken stickers.
|
| Most recently, FTC started to raise awareness and crack down
| on some abuse: https://www.ftc.gov/news-events/news/press-
| releases/2024/07/....
|
| Will take a long time to de-program and by that time nothing
| will be replaceable to matter due to industries march towards
| preventing repair altogether.
| mschuster91 wrote:
| > There is no consumer market for 4TB+ SSDs. There never was,
| and there probably won't be for the foreseeable future.
|
| Gamers certainly are a market. Borderlands 3 for example, a
| 2019 game, clocks in at 75GB on Steam, GTA 5 at 105 GB, MSFS
| 150 GB. And that's all OLD games. CoD Black Ops wants 175 GB,
| GTA 6 is rumored to want anything from 100 to 300 GB. You
| don't want that on spinning rust.
| Detrytus wrote:
| Are you going to have all those installed at the same time?
| I mean, most players will focus on one, two games at the
| time, and also Steam or GoG will just backup your saved
| games to the cloud, so you can uninstall them, and come
| back to your old games later.
| Dylan16807 wrote:
| And if uninstalling is too far, inactive games can go to
| an extra cheap hard drive and it'll only take 10-15
| minutes to move 100GB back to your SSD.
|
| I was hoping SSDs would get price competitive with hard
| drives but the progress sure has been bad lately...
|
| (It's possible to even set up a system that lets you play
| a game _while_ it 's being moved over to SSD, but sadly
| there aren't any easy ways to do that right now.)
| mystifyingpoi wrote:
| > have been conditioned to store their data on their phones
|
| This is 100% true. I have a family member that literally has
| a decade of family photos stored in WhatsApp conversations.
| 10 gigs app storage used on some old iPhone, no backup.
| ksec wrote:
| HDD isn't any different. Peice per TB has been flat for many
| years. You get higher capacity for Hyperscaler, but those are
| not intended for consumers and you need to pre book in advance
| to get them.
|
| SSD price may have fluctuating for the last few years but their
| cost model are now similar to HDD. And so is DRAM.
|
| Mainly cost to produce GB of DRAM / NAND / HDD are roughly the
| same for many years. You may get better performance or lower
| energy usage. But cost hast changed. And all fluctuations in
| market are supple and demand dynamics, which is why many saw
| 4TB for $150 in 2023 and thought things will drop soon. But
| that has not been the case.
|
| We need breakthroughs to further reduce the cost per GB.
| Although one could argue we have half the cost already if we
| accounted for inflation for the past 20 years.
| AtlasBarfed wrote:
| The SSDs come from, very generally speaking, the same
| semiconductor segment that has been busted multiple times for
| price fixing in DRAM.
|
| Not that hyperconsolidation in HDDs isn't vulnerable to the
| same things, but the management playbook of these guys is to
| fix and inflate as much as possible.
| Jerry2 wrote:
| What's a fair price for a TB of HDD? SSD? Which high-capacity
| SSDs are worth buying?
|
| I'm not sure if there are any sites tracking this. Anyway, I
| need to buy 30TB of storage this year so I can upgrade my NAS
| and make it last few years. Thanks for any replies from
| anyone who has an opinion!
| wmf wrote:
| HDD: $10/TB
|
| SSD: $50-100/TB
| nixgeek wrote:
| Most new drives are sold into consumer/end user retail
| around $20/TB and only seem to dip a little during sales
| (with most sellers also quantity limiting any sales,
| also). Getting to $10/TB is possible but typically
| involves buying manufacturer recertified, and may involve
| going smaller (14-16TB drives) than you might prefer.
|
| I managed to find 64x Seagate Exos 20TB for $13/TB new
| about 2 years ago, on NewEgg of all places, but I've
| never seen that deal repeat. :(
|
| All the new 30TB+ HDDs using HAMR technology from Seagate
| and WD still feel like expensive unobtainium.
| synack wrote:
| https://diskprices.com/
| toast0 wrote:
| > Prices for HDD do drop when the TB available rises but there
| seems to be a "floor" price.
|
| For SSD, there definitely appears to be a floor price.
|
| The floor price for new hard drives is somewhere around
| $50-$80. When a drive at a certain capacity is only sellable
| for $50, most of the options disappear. Looking at newegg, you
| can get a 1TB drive for $60, 2TB for $65, and 4TB for $75 ...
| The price floor is around there. But if you want the best $/TB,
| you've got to get larger drives.
|
| For SSDs, the floor is a lot lower. You can get a 128gb ssd for
| $22, 256Gb for $25, 512GB for $33, 1TB for $50, and then after
| that $/TB stays pretty consistent, there's not a lot of
| reduction in cost due to density like with hard drives.
| torginus wrote:
| Imo the problem of SSDs is that even super-cheap products
| easily hit or exceed the sweet spot (which for me is at least
| 1TB of capacity and 1-2GB/s of read write speed, and lack of
| judder/slowdown when near capacity).
|
| A ton of affordable SSDs can do this, and after that (well, I'd
| pay for 2TB but not more), any upgrade is not noticeable for
| the end user.
| sleepyguy wrote:
| There is collusion between manufacturers to control prices.
| Just like other industries, they learned the hard way with
| overproduction and capacity. Samsung was able to convince
| everyone to cut back. In Dec of 23, I purchased a Crucial P5
| Plus Gen 4 2 TB SSD for $86 off Amazon and it was soon
| afterwards Samsung cut back drastically, with competitors
| following.
| userbinator wrote:
| Absolutely zero mention of retention for a storage device is
| disturbing.
|
| The endurance figures seem to suggest anywhere between 6.6k and
| 11k cycles, which is both a wide range and unusually high for TLC
| flash - this is the normally expected range for decent MLC and 5
| years of retention, so I suspect they're massaging the retention
| downwards to get those numbers.
|
| Related: https://news.ycombinator.com/item?id=43702193
| jauntywundrkind wrote:
| To ground these endurance figures a little more concretely,
| consumer drives will advertise 600TBW:TB, or 600 cycles!
| Starting at 10x that is a very solid starting place!
|
| On the other hand, an enterprise drive like Kioxia CM7 will
| offer either 1 or 3 drive writes per day (for regular and
| write-intensive drive models, respectively), across the 5 year
| warranty. That's ~1800 cycles or just shy of 5500 cycles.
| userbinator wrote:
| Enterprise drives have always been rated for lower retention
| and hence higher cycles than consumer drives, since those are
| inversely correlated.
| daymanstep wrote:
| Do you have a source for that claim? Everything I've read
| suggests that data retention is mostly about the write
| temperature vs storage temperature, and that enterprise
| drives have about equivalent retention to consumer drives.
|
| By retention I'm assuming you're referring to the amount of
| time it takes for data loss to occur on SSDs in cold
| unpowered storage.
| userbinator wrote:
| From the horse's mouth:
| https://americas.kioxia.com/content/dam/kioxia/en-
| us/busines... (See graph on page 2.)
|
| https://www.macronix.com/Lists/ApplicationNote/Attachment
| s/1... (See graph on page 3.)
|
| Then look up the retention specs for enterprise drives
| and compare to consumer ones, and the conclusion is
| obvious.
| daymanstep wrote:
| Correct me if I'm mistaken but it looks to me like your
| graphs are talking about the number of P/E cycles
| accumulated, rather than the number of P/E cycles that a
| drive is rated for?
|
| What this seems to suggest is that as a drive gets more
| "worn out", its data retention gets worse.
|
| But I don't see how that can be taken to imply that
| enterprise drives have worse data retention than consumer
| drives. Nothing that I've seen suggests this.
| zozbot234 wrote:
| > What this seems to suggest is that as a drive gets more
| "worn out", its data retention gets worse.
|
| This is what informal tests (i.e. via
| scrubbing/resilvering the drive after leaving it powered
| off for a long time) have found. Retention/data remanence
| is remarkably good for a drive that has been written over
| just once, and quite bad (i.e. you start seeing bit
| errors) for one that's almost worn out. This is actually
| very good news for the EEPROM-like use case where
| rewrites are quite rare.
|
| (Note that "almost worn out" in this case can mean going
| _far_ beyond the formal total-data-written rating of the
| drive. We 're talking the range where the hardware itself
| is about to croak.)
| userbinator wrote:
| _But I don 't see how that can be taken to imply that
| enterprise drives have worse data retention than consumer
| drives_
|
| Look up the specs. Commonly quoted as 3 months for
| enterprise ratings but the whole picture is in these
| tables:
|
| https://www.legitreviews.com/wp-
| content/uploads/2015/05/ssd-...
|
| Page 22 of this "says the quiet part out loud": https://w
| ww.snia.org/sites/default/files/AnilVasudeva_Are_SS...
| ("Lower Data Retention allows for higher endurance")
| daymanstep wrote:
| I'm not sure I fully understand what that page is saying.
|
| It is my understanding that JEDEC standard tests the data
| retention of the "worst case" scenario where a drive is
| fully worn out, i.e the drive has reached its maximum
| rated P/E cycles.
|
| If I'm understanding correctly, that page you linked is
| saying that enterprise drives have firmware that
| essentially allows more P/E cycles, which then means that
| at the end of those cycles, the drive will be more "worn
| out" and thus will have a worse data retention.
|
| But in a real world usage scenario where we subject a
| consumer SSD and an enterprise SSD to the same number of
| P/E cycles, would they have different data retention? I
| thought the JEDEC data was only for end-of-life
| scenarios.
| wtallis wrote:
| > But in a real world usage scenario where we subject a
| consumer SSD and an enterprise SSD to the same number of
| P/E cycles, would they have different data retention?
|
| Probably not, assuming they're using the same underlying
| media and same strength of ECC and that the amount of
| host data written was appropriately adjusted to account
| for the different capacities and overprovisioning ratios
| to ensure the actual P/E cycles seen by the NAND were the
| same.
|
| As you write more data, the consumer drive would be out
| of warranty first, while the enterprise drive would still
| be under warranty but not spec'd to retain data for as
| long as the worn-out consumer drive. So for either drive,
| the manufacturer isn't guaranteeing 1 year retention past
| the rated endurance of the consumer drive.
| userbinator wrote:
| _fully worn out, i.e the drive has reached its maximum
| rated P /E cycles._
|
| That differs between enterprise and consumer - and the
| reason why the former is rated higher is because they've
| reduced the retention spec (to almost 1/4th).
|
| _But in a real world usage scenario where we subject a
| consumer SSD and an enterprise SSD to the same number of
| P /E cycles, would they have different data retention?_
|
| No, and that's the whole point of this: the same flash,
| with different definitions of "worn out", is quite
| misleading as they're just looking at different points on
| the same curve. It's all obfuscated marketing.
|
| Incidentally, this is also why those widely-publicised
| tests that claim SSD endurance is not a problem by
| continuously writing until absolute failure and seeing
| many times the rated endurance (e.g.
| https://linustechtips.com/topic/327024-the-ssd-endurance-
| exp... ) are extremely misleading (albeit enlightening on
| how "enterprise" ratings are being calculated): they are
| showing how many cycles the flash will take before it's
| too leaky to store data long enough for the next
| verification pass, which may be less than an hour away.
| At that point it's almost behaving more like DRAM than
| nonvolatile memory.
| daymanstep wrote:
| Oh wow, yeah I see your point, that is indeed extremely
| misleading.
|
| I had always thought that enterprise SSDs used higher
| quality flash than consumer SSDs because of the higher
| endurance guarantees - that was why I bought them. Now I
| feel like a big reason to buy enterprise SSD has been
| removed.
|
| I am flabbergasted, to be honest. And I feel a bit
| cheated that I am paying much more for the same quality
| flash.
|
| So would it be fair to say that the only reason to pay
| for the enterprise SSD premium is the power loss
| protection and more reliable firmware?
| wtallis wrote:
| Definitely don't think of enterprise vs consumer SSDs as
| _good_ vs _bad_ ; they're optimizing for different use
| cases.
|
| Enterprise SSDs get you power loss protection and
| firmware QA aimed at server workloads and operating
| systems, and performance tuning prioritizing consistent
| sustained performance, and larger form factors with
| enabling higher capacity and higher power.
|
| Consumer SSDs get you higher peak performance (eg. SLC
| caching) and orders of magnitude better idle power
| savings and QA against Windows and its NVMe driver, in
| form factors suitable for laptops and not requiring
| direct airflow over the SSD.
|
| A very long time ago when the SSD market was still quite
| immature, there was a time period where "consumer" SSDs
| were little more than cut-down enterprise SSDs with
| inferior NAND and fewer features. But that changed well
| before NVMe showed up.
| justincormack wrote:
| Generally they just chop off some space to allow for more to
| be used when it wears out, which is why enterprise is 3.84TB
| not 4TB. If you partition the drive smaller and never use the
| rest you can achieve similar endurance.
| drtgh wrote:
| Very disturbing, the article talks about the number of bits to
| be read per cell like if it were only a matter of speed.
|
| In addition to your comment (related), when 3D-NAND cells are
| read, interference by the traces (charge-trap disturbs)
| requires the neighbour cells to be refreshed with writes, if
| the controller wants to conserve data integrity. This did not
| happen with 2D-NAND in the past.
|
| Reading data from one cell in 3D-NAND involves writing cells;
| reading data in 3D-NAND consumes disk endurance.
|
| (Not to mention, temperature/number of layers/endurance)
| zozbot234 wrote:
| The read disturb effect happens with 2D-NAND, it's just rare.
| pkaye wrote:
| I used to work in SSD controller firmware. This kind of issue
| existed more than 10 years ago. To achieve higher capacity
| with each generation of NAND you are trading off everything
| else (endurance, retention, read/program times, etc) little
| by little. 20 years ago it was so rare to see any kind of
| errors with SLC NAND that error detection and handling was
| fairly simple.
| userbinator wrote:
| I have some small USB drives from that era with SLC rated
| for 10 years of retention after 100k cycles, meaning a 64MB
| drive has a total endurance of 6.4TB. True binary capacity
| too, with no wear leveling either, as only the spares on
| each page were needed for a simple ECC.
|
| Too bad planned obsolescence got in the way, or we would've
| ended up today with bigger SLC drives that are fast and
| simple and just as reliable.
| Dylan16807 wrote:
| There's no planned obsolescence for my use case. I've
| never done enough writes to wear out an SSD. While I
| might buy an SLC flash drive if it was properly
| available, for internal drives TLC has barely any
| downsides. I very rarely get limited to 500MB/s, I need
| to turn it on sometimes, and I get 2.8x the space. Sounds
| great.
| devttyeu wrote:
| I don't think most people grasp how abstractly high even 1 DWPD
| is compared to enterprise HDDs. On the enterprise side you'll
| often read that a hard drive is rated for maybe 550TB/year,
| translating to 0.05~0.1 DRWPD [1] (yes, combined read AND
| write) and you have to be fine with that. (..yeah admittedly
| the workloads for each are quite different, you can
| realistically achieve >1 DWPD on an nvme with e.g. a large LSM
| database).
|
| What makes NVMe endurance ratings even better (though not for
| warranty purposes) is when your workload has sequential writes
| you can expect much higher effective endurance as most DWPD
| metrics are calculated for random 4k write, which is just about
| the worst case for flash with multi-megabyte erase blocks. It's
| my understanding that it's also in large part why there is some
| push for Zoned (hm-smr like) NVMe, where you can declare much
| higher DWPD.
|
| * [1] https://documents.westerndigital.com/content/dam/doc-
| library...
| zozbot234 wrote:
| I assume that flash translation layers use LSM-like patterns
| underneath to cope with small random writes. The best case
| for flash with a good translation layer is data that can be
| _erased /discarded_ in bulk, since this minimizes write
| amplification. This is close enough to the "large sequential
| writes" case but not necessarily equivalent.
| kachapopopow wrote:
| 140tb of writes, so us-, wait, that's petabytes isn't it.
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