15 ms·

Unpowered SSDs slowly lose data

770 points by amichail 11mo ago

lofaszvanitt 11mo ago
xda-developers..... reliable source. nonetheless time to ask the ssd makers whats their take on this. they have support,time to write to them.
paulkrush 11mo ago
I had to search around and feel like a dork not knowing this. I have my data backed up, but I keep the SSDs because it's nice to have the OS running like it was... I guess I need to be cloning the drives to ISOs and storing on spinning rust.
- dpoloncsak 11mo ago
  I could be wrong, but I believe the general consensus is along the lines of "SSDs for in-use data, it's quicker and wants to be powered on often. HDDs for long-term storage, as they don't degrade when not in use nearly as fast as SSDs do.
  - joezydeco 11mo ago
    I've been going through stack of external USB drives with laptop disks in them. They're all failing in some form or another. I'm going to have to migrate it all to a NAS with server-class drives I guess
    - Yokolos 11mo ago
      At the very least, you can usually still get the data off of them. Most SSDs I've encountered with defects failed catastrophically, rendering the data completely inaccessible.
  - PunchyHamster 11mo ago
    I'd imagine HDDs also don't like not spinning for years(as mechanical elements generally like to be used from time to time). But at least platters itself are intact
- pluralmonad 11mo ago
  I learned this when both my old laptops would no longer boot after extended off power time (couple years). They were both stored in a working state and later both had SSDs that were totally dead.
  - justin66 11mo ago
    Were the SSDs toasted, or were you able to reinstall to them?
    - pluralmonad 11mo ago
      D.E.A.D. Had to replace them.
- gosub100 11mo ago
  or you could power them on 1-2x /year.
  - ggm 11mo ago
    Power them on and run something to exercise the read function over every bit. Thats why a ZFS filesystem integrity check/scrub is the useful model. I'm unsure if dd if=/the/disk of=/dev/null does the read function.
    - fragmede 11mo ago
      why would it not? it's a low level tool to do exactly that. you could "of" it to somewhere else if you're worried it's not. I like to | hexdump -C, on an xterm set to a green font on a black background for a real matrix movie kind of feel.
sevensor 11mo ago
Flash is programmed by increasing the probability that electrons will tunnel onto the floating gate and erased by increasing the probability they will tunnel back off. Those probabilities are never zero. Multiply that by time and the number of cells, and the probability you don’t end up with bit errors gets quite low. The difference between slc and mlc is just that mlc has four different program voltages instead of two, so reading back the data you have to distinguish between charge levels that are closer together. Same basic cell design. Honestly I can’t quite believe mlc works at all, let alone qlc. I do wonder why there’s no way to operate qlc as if it were mlc, other than the manufacturer not wanting to allow it.
- Someone 11mo ago
  > I do wonder why there’s no way to operate qlc as if it were mlc, other than the manufacturer not wanting to allow it. You can run an error-correcting code on top of the regular blocks of memory, storing, for example (really an example; I don’t know how large the ‘blocks’ that you can erase are in flash memory), 4096 bits in every 8192 bits of memory, and recovering those 4096 bits from each block of 8192 bits that you read in the disk driver. I think that would be better than a simple “map low levels to 0, high levels to 1” scheme.
- bobmcnamara 11mo ago
  > I do wonder why there’s no way to operate qlc as if it were mlc, other than the manufacturer not wanting to allow it. Loads of drives do this(or SLC) internally. Though it would be handy if a physical format could change the provisioning at the kernel accessible layer.
- em500 11mo ago
  > Honestly I can’t quite believe mlc works at all, let alone qlc. I do wonder why there’s no way to operate qlc as if it were mlc, other than the manufacturer not wanting to allow it. Manufacturers often do sell such pMLC or pSLC (p = pseudo) cells as "high endurance" flash.
- testartr 11mo ago
  the market demands mostly higher capacity tlc/qlc works just fine, it's really difficult to consume the erase cycles unless you really are writing 24/7 to the disk at hundred of megabytes a second
brian-armstrong 11mo ago
Powering the SSD on isn't enough. You need to read every bit occasionally in order to recharge the cell. If you have them in a NAS, then using a monthly full volume check is probably sufficient.
- Izkata 11mo ago
  Huh. I wonder if this is why I'd sometimes get random corruption on my laptop's SSD. I'd reboot after a while and fsck would find issues in random files I haven't touched in a long time.
  - formerly_proven 11mo ago
    Unless your setup is a very odd Linux box, fsck will never check the consistency of file contents.
    - suspended_state 11mo ago
      But metadata is data too, right? I guess the next question is, would it be possible for parts of the FS metadata to remain untouched for a time long enough for the SSD data corruption process to occur.
    - Izkata 11mo ago
      It found problems in the tree - lost files, wrong node counts, other stuff - which led to me finding files that didn't match previous backups (and when opened were obviously corrupted, like the bottom half of an image being just noise). Once I found this was a problem I've also caught ones that couldn't be read (IOError) that fsck would delete on the next run. I may not have noticed had fsck not alerted me something was wrong.
    - giantrobot 11mo ago
      A ZFS scrub (default scheduled monthly) will do it.
  - brian-armstrong 11mo ago
formerly_proven 11mo ago
> Even the cheapest SSDs, say those with QLC NAND, can safely store data for about a year of being completely unpowered. More expensive TLC NAND can retain data for up to 3 years, while MLC and SLC NAND are good for 5 years and 10 years of unpowered storage, respectively. This is somewhat confused writing. Consumer SSDs usually do not have a data retention spec, even in this very detailed Micron datasheet you won't find it: https://advdownload.advantech.com/productfile/PIS/96FD25-S2TB-MX/file/96FD25-S2TB-MX_datasheet20220308104755.PDF https://advdownload.advantech.com/productfile/PIS/96FD25-S2T... Meanwhile the data retention spec for enterprise SSDs is at the end of their rated life, which is usually a DPWD/TBW intensity you won't reach in actual use anyway - that's where numbers like "3 months @ 50 °C" or whatever come from. In practice, SSDs don't tend to loose data over realistic time frames. Don't hope for a "guaranteed by design" spec on that though, some pieces of silicon are more equal than others.
- Yokolos 11mo ago
  Any given TBW/DWPD values are irrelevant for unpowered data retention. Afaik, nobody gives these values in their datasheet and I'm wondering where their numbers are from, because I've never seen anything official. At this point I'd need to be convinced that the manufacturers even know themselves internally, because it's never been mentioned by them and it seems to be outside the intended use cases for SSDs
  - formerly_proven 11mo ago
    Example: https://www.ssd.group/wp-content/uploads/2022/07/PM1733-25-SSD-Datasheet_v1.3_for-General.pdf https://www.ssd.group/wp-content/uploads/2022/07/PM1733-25-S... > Component Design Life 5 years > TBW 14 PB for 7.68 TB drives > Data Retention 3 months And then 2.7.3 explains that this number applies for 40 °C ambient, not the operating/non-operating range (up to 85 °C).
    - Yokolos 11mo ago
      That's literally just the JEDEC spec.
bossyTeacher 11mo ago
This is why I would rather pay someone a couple of dollars per year to handle all this for me. If need be pay two providers to have a backup.
- loloquwowndueo 11mo ago
  Who do you pay for this? (To rephrase : which cloud storage vendors do you use?) interested in the $2/month price point :)
  - ggm 11mo ago
    tell me about this $2/week filestore option. I'm interested.
    - 867-5309 11mo ago
      continuing the bizarre trend, I'm here for the $2/day deal
      - topato 11mo ago
        I'D love to be paying $2/minute!
      - bigstrat2003 11mo ago
        That would be Tarsnap. Cool product and the owner is a good dude, but good Lord is it expensive. I would love to support him but just can't afford it.
  - PunchyHamster 11mo ago
    Backblaze B2 is $6TB/mo, so if you have around 300GB... stuff like restic or kopia backups nicely to it
    - markhahn 11mo ago
      $72/yr is somewhere around 3x purchase price (per year). BB seems to be pretty smart about managing their exposure, infrastructure overhead, etc.
traceroute66 11mo ago
I assume this blog is a re-hash of the JDEC retention standards[1]. The more interesting thing to note from those standards is that the required retention period differs between "Client" and "Enterprise" category. Enterprise category only has power-off retention requirement of 3 months. Client category has power-off retention requirement of 1 year. Of course there are two sides to every story... Enterprise category standard has a power-on active use of 24 hours/day, but Client category only intended for 8 hours/day. As with many things in tech.... its up to the user to pick which side they compromise on. [1]https://files.futurememorystorage.com/proceedings/2011/20110810_T1B_Cox.pdf https://files.futurememorystorage.com/proceedings/2011/20110...
- throw0101a 11mo ago
  > I assume this blog is a re-hash of the JDEC retention standards[1]. Specifically in JEDEC JESD218. (Write endurance in JESD219.)
- tcfhgj 11mo ago
  With 1 year power-off retention you still loose data, so still a compromise on data retention
  - deleted 11mo ago
    [deleted]
- Springtime 11mo ago
  In the longer JEDEC overview document[1] it explains that in the ideal 'direct' testing method retention testing is only performed after the endurance testing. Which is only after the drive has had its max spec'd TBW written to it. While if the endurance testing would exceed 1000 hours an extrapolated approach can be used to stress below the TBW but using accelerated techniques (including capping the max writable blocks to increase wear on the same areas). Which is less dramatic than the retention values seem at first and than what gets communicated in articles I've seen. Even in the OP's linked article it takes a comment to also highlight this, while the article itself only cites its own articles that contain no outside links or citations. [1] https://www.jedec.org/sites/default/files/Alvin_Cox%20%5BCompatibility%20Mode%5D_0.pdf https://www.jedec.org/sites/default/files/Alvin_Cox%20%5BCom...
testartr 11mo ago
what is the exact protocol to "recharge" an ssd which was offline for months? do I just plug it in and let the computer on for a few minutes? does it needs to stay on for hours? do I need to run a special command or TRIM it?
- PunchyHamster 11mo ago
  I'd imagine full read of the whole device might trigger any self-preservation, but I'd also imagine it's heavily dependent on manufacturer and firmware
- PaulKeeble 11mo ago
  We really don't know. One thing I wish some of these sites would do is actually test how long it takes for the drives to decay and also do a retest after they have been left powered for say 10 minutes to an hour, read completely, written to a bit etc and see if they can determine what a likely requirement is. The problem is the test will take years, be out of date by the time its released and new controllers will be out with potentially different needs/algorithms.
  - unsnap_biceps 11mo ago
    There was one guy who tested this https://www.tomshardware.com/pc-components/storage/unpowered-ssd-endurance-investigation-finds-severe-data-loss-and-performance-issues-reminds-us-of-the-importance-of-refreshing-backups https://www.tomshardware.com/pc-components/storage/unpowered... The data on this SSD, which hadn't been used or powered up for two years, was 100% good on initial inspection. All the data hashes verified, but it was noted that the verification time took a smidgen longer than two years previously. HD Sentinel tests also showed good, consistent performance for a SATA SSD. Digging deeper, all isn't well, though. Firing up Crystal Disk Info, HTWingNut noted that this SSD had a Hardware ECC Recovered value of over 400. In other words, the disk's error correction had to step in to fix hundreds of data-based parity bits. ... As the worn SSD's data was being verified, there were already signs of performance degradation. The hashing audit eventually revealed that four files were corrupt (hash not matching). Looking at the elapsed time, it was observed that this operation astonishingly took over 4x longer, up from 10 minutes and 3 seconds to 42 minutes and 43 seconds. Further investigations in HD Sentinel showed that three out of 10,000 sectors were bad and performance was 'spiky.' Returning to Crystal Disk Info, things look even worse. HTWingNut notes that the uncorrectable sectors count went from 0 to 12 on this drive, and the hardware ECC recovered value went from 11,745 before to 201,273 after tests on the day.
BaardFigur 11mo ago
I don't use my drive much. I still boot it up snd write some data, just not the long term one. Am I in risk?
- zozbot234 11mo ago
  AIUI, informal tests have demonstrated quite a bit of data corruption in Flash drives that are literally so worn out that they might as well be about to fail altogether - well beyond any manufacturer's actual TBW specs - but not otherwise, least of all in new drives that are only written once over for the test. It seems that if you don't wear out your drive all that much you'll have far less to worry about.
  - userbinator 11mo ago
    No, even drives written once have started showing a rise in (correctable) errors after 2 years: https://news.ycombinator.com/item?id=43739028 https://news.ycombinator.com/item?id=43739028
    - zozbot234 11mo ago
      That's a slight rise in ECC which is entirely expected. Flash storage can be expected to rely on error correction as part of normal functioning; it's not an abnormal condition.
      - userbinator 11mo ago
        Bit errors occurring after only 2 years, on flash that has been written to once, is not good at all.
yapyap 11mo ago
good to know but apart from some edge cases this doesnt matter that much
dale_glass 11mo ago
So on the off-chance that there's a firmware engineer in here, how does this actually work? Like does a SSD do some sort of refresh on power-on, or every N hours, or you have to access the specific block, or...? What if you interrupt the process, eg, having a NVMe in an external case that you just plug once a month for a few minutes to just use it as a huge flash drive, is that a problem? What about the unused space, is a 4 TB drive used to transport 1 GB of stuff going to suffer anything from the unused space decaying? It's all very unclear about what all of this means in practice and how's an user supposed to manage it.
- zozbot234 11mo ago
  Typically unused empty space is a good thing, as it will allow drives to run in MLC or SLC mode instead of their native QLC. (At least, this seems to be the obvious implication from performance testing, given the better performance of SLC/MLC compared to QLC.) And the data remanence of SLC/MLC can be expected to be significantly better than QLC.
  - gruez 11mo ago
    >as it will allow drives to run in MLC or SLC mode instead of their native QLC That depends on the SSD controller implementation, specifically whether it proactively moves stuff from the SLC cache to the TLC/QLC area. I expect most controllers to do this, given that if they don't, the drive will quickly lose performance as it fills up. There's basically no reason not proactively move stuff over.
    - kasabali 11mo ago
      Cheap DRAM-less controllers usually wait until the drive is almost full to start folding. And then they'll only be folding just enough to free up some space. Most benchmark results are consistent with this behavior.
- fairfeather 11mo ago
  SSD firmware engineer here. I work on enterprise stuff, so ymmv on consumer grade internals. Generally, the data refresh will all happen in the background when the system is powered (depending on the power state). Performance is probably throttled during those operations, so you just see a slightly slower copy while this is happening behind the scenes. The unused space decaying is probably not an issue, since the internal filesystem data is typically stored on a more robust area of media (an SLC location) which is less susceptible to data loss over time. As far as how a user is supposed to manage it, maybe do an fsck every month or something? Using an SSD like that is probably ok most of the time, but might not be super great as a cold storage backup.
tzs 11mo ago
What about powered SSDs that contain files that are rarely read? My desktop computer is generally powered except when there is a power failure, but among the million+ files on its SSD there are certainly some that I do not read or write for years. Does the SSD controller automatically look for used blocks that need to have their charge refreshed and do so, or do I need to periodically do something like "find / -type f -print0 | xargs -0 cat > /dev/null" to make sure every file gets read occasionally?
- JensenTorp 11mo ago
  I also need an answer to this.
  - dboreham 11mo ago
    It's fine. But the whole drive can turn to dust at any time, of course.
    - danparsonson 11mo ago
      I stopped buying cursed second-hand drives for exactly this problem.
      - formerly_proven 11mo ago
        The supply chain got you covered and will randomly hand you inofficially-refurbished drives as new ones ;)
- seg_lol 11mo ago
  You should absolutely be doing a full block read of your disk, dd if=/dev/disk of=/dev/null every couple weeks
  - topato 11mo ago
    pretty accurate username
jcynix 11mo ago
Hmm, so what about these modern high density hard drives which store track parameters for their servos in on-board flash (aka OptiNAND)? Do we get "spinning rust" which might loose the information where exactly it stored the data? https://blog.westerndigital.com/optinand-explained/ https://blog.westerndigital.com/optinand-explained/
- binaryturtle 11mo ago
  I wonder too. I don't trust SSDs/ flash for my archives, hence I'm stuck on max. 18TB drives atm.
- markhahn 11mo ago
  shouldn't really be a problem, since the capacity required for this use is so low. the real issue here is QLC in which the flash cell's margins are being squeezed enthusiastically...
- userbinator 11mo ago
  I think you're talking about two different things; "adaptives" are usually stored in EEPROM or the MCU's NOR flash, which is basically better-than-SLC levels of reliability, especially as they're written once and treated as ROM after that. OptiNAND is a "SSHD" and thus has the same concerns with retention as an SSD. https://en.wikipedia.org/wiki/Hybrid_drive https://en.wikipedia.org/wiki/Hybrid_drive
storus 11mo ago
I thought that was an ancient issue with Samsung 740? I had that one and it was slowly losing speed when unpowered due to an accumulation of errors and rewriting the individual sectors once for the whole drive made it work fine for a year.
TacticalCoder 11mo ago
So basically if you like to put SSDs on shelves (for offline backups), you should read them from scratch once in a while? I rotate religiously my offline SSDs and HDDs (I store backups on both SSDs and HDDs): something like four at home (offline onsite) and two (one SSD, one HDD) in a safe at the bank (offline offsite). Every week or so I rsync (a bit more advanced than rsync in that I wrap rsync in a script that detects potential bitrot using a combination of an rsync "dry-run" and known good cryptographic checksums before doing the actual rsync [1]) to the offline disks at home and then every month or so I rotate by swapping the SSD and HDD at the bank with those at home. Maybe I should add to the process, for SSDs, once every six months: ... $ dd if=/dev/sda | xxhsum I could easily automate that in my backup'ing script by adding a file lastknowddtoxxhash.txt containing the date of the last full dd to xxhsum, verifying that, and then asking, if a SSD is detected (I take it on a HDD it doesn't matter), if a full read to hash should be done. Note that I'm already using random sampling on files containing checksums in their name, so I'm already verifying x% of the files anyway. So I'd probably be detecting a fading SSD quite easily. Additionally I've also got a server with ZFS in mirroring so this, too, helps keep a good copy of the data. FWIW I still have most of the personal files from my MS-DOS days so I must be doing something correctly when it comes to backing up data. But yeah: adding a "dd to xxhsum" of the entire disks once every six months in my backup'ing script seems like a nice little addition. Heck, I may go hack that feature now. [1] otherwise rsync shall happily trash good files with bitrotten ones
nubinetwork 11mo ago
I've got some old SSDs just to test this myself, the old 256gb corsairs I tested previously were fine after a year and a half, but I might have misplaced them...(they only had 10% write life left, so no huge loss) the 512gb samsungs on my desk should be getting pretty ripe soon though, I'll have to check those too.
canadiantim 11mo ago
What is the best way to store data for a long time then?
- markhahn 11mo ago
  all the major players say "tape". (but that's partly for practical issues like scaling and history)
  - deleted 11mo ago
    [deleted]
  - octorian 11mo ago
    And yet nobody wants to actually offer a tape-based solution that's practical, easy to get, holds enough data, and doesn't cost a blithering fortune. Even if you are willing to spend that small fortune, good luck actually getting all the parts together without enterprise contracts.
- schneehertz 11mo ago
  Depending on your time requirements, carving it into a stone tablet is generally a good choice
dboreham 11mo ago
Quick note to not store any valuable data on a single drive. And when you store it on two drives, don't use the same kind of drive. (Speaking from bitter experience using spinning drives in servers that had a firmware bug where they all died at the time number of seconds of power-on time).
- burnt-resistor 11mo ago
  That's kicking the can down the road for double the cost. Only a backup on spinning rust is actually a backup. Furthermore, replication isn't a backup.
userbinator 11mo ago
One key point about retention which is not often mentioned, and indeed neither does this article, is that retention is inversely proportional to program/erase cycles and decreases exponentially with increasing temperature. Hence why retention specs are usually X amount of time after Y cycles at Z temperature. Even a QLC SSD that has only been written to once, and kept in a freezer at -40, may hold data for several decades. Manufacturers have been playing this game with DWPD/TBW numbers too --- by reducing the retention spec, they can advertise a drive as having a higher endurance with the exact same flash. But if you compare the numbers over the years, it's clear that NAND flash has gotten significantly worse; the only thing that has gone up, multiplicatively, is capacity, while endurance and rentention have both gone down by a few orders of magnitude. For a long time, 10 years after 100K cycles was the gold standard of SLC flash. Now we are down to several months after less than 1K cycles for QLC.
- RachelF 11mo ago
  Endurance going down is hardly a surprise given that the feature size has gone down too. The same goes for logic and DRAM memory. I suspect that 2035 years time, hardware from 2010 will work, while that from 2020 will be less reliable.
  - Dylan16807 11mo ago
    As far as I'm aware flash got a bit of a size boost when it went 3D and hasn't shrunk much since then. If you use the same number of bits per cell, I don't know if I would expect 2010 and 2020 or 2025 flash to vary much in endurance. For logic and DRAM the biggest factors are how far they're being pushed with voltage and heat, which is a thing that trends back and forth over the years. So I could see that go either way.
  - lotrjohn 11mo ago
    Completely anecdotal, and mostly unrelated, but my NES from 1990 is still going strong. Two PS3’s that I have owned simply broke. CRTs from 1994 and 2002 still going strong. LCD tvs from 2012 and 2022 just went kaput for no reason. Old hardware rocks.
cosmic_cheese 11mo ago
Is there any type of flash-based storage (preferably accessible to end users) that focuses on long term data retention? If not, that feels like a substantial hole in the market. Non-flash durable storage tend to be annoying or impractical for day to day use. I want to be able to find a 25 year old SD card hiding in some crevice and unearth an unintentional time capsule, much like how one can pick up 20+ year old MiniDiscs and be able to play the last thing their former owners recorded to them perfectly.
- 55873445216111 11mo ago
  Yes, NOR Flash guarantees 20 years data retention. It's about $30/GiB.
- tensility 11mo ago
  There are also expensive high-grade SLC NAND flash chips available that offer significantly higher retention time than the cheaper commodity channel TLC NAND (i.e. 10 years versus 3 years). In general, though, whether NAND or NOR, the fundamental way that flash works is by creating an isolated voltage charge for each bit (or several bits, for TLC), making it effectively a vast grid of very tiny batteries. Like all batteries, no matter how well-stored, they will eventually leak energy to the point where the voltage levels change enough to matter. Further, it's not enough to simply make power available to this grid since the refresh of the cells requires active management by a nand controller chip and its associated software stack.
coppsilgold 11mo ago
My scrub script: dd if=$1 of=/dev/null iflag=direct bs=16M status="progress" smartctl -a $1 If someone wants to properly study SSD data-retention they could encrypt the drive using plain dm-crypt and fill the encrypted volume with zeroes and check at some time point afterwards to see if there are any non-zero blocks. This is an accessible way (no programming involved) to let you write random data to the SSD and save it without actually saving the entire thing - just the key. It will also ensure maximum variance in charge levels of all the cells. Will also prevent the SSD from potentially playing tricks such as compression.
burnt-resistor 11mo ago
Not having a (verified) backup is driving without a seatbelt.
Wowfunhappy 11mo ago
> But, most people don't need to worry about it. [...] You should always have a backup anyway. [...] Backing up your data is the simplest strategy to counteract the limitations of storage media. Having multiple copies of your data on different types of storage ensures that any unexpected incidents protect your data from vanishing forever. This is exactly what the 3-2-1 backup rule talks about: 3 copies of data on at least 2 different storage media, with 1 copy stored off-site. Um. Backups seem like exactly why I might have data on an unpowered SSD. I use HDDs right now because they're cheaper, but that might not be true some day. Also, I would expect someone less technically inclined than I am to just use whatever they have lying around, which may well be an SSD.
- jollyllama 11mo ago
  Yeah. That part was so out of touch, I have to wonder who they're carrying water for. Most people backup their data? What planet does the author live on?
behringer 11mo ago
The article implies this is not a concern for "regular" people. That is absolutely false. How many people get their family photos when they finally decide to recycle that 15 year old PC in the basement? How many people have a device that they may only power up ever few years, like on vacation. In fact, I have a device that I've only used on rare occasions these days (an arcade machine) that now I suspect I'll have to reinstall since It's been 2 or 3 years since I've last used it. This is a pretty big deal that they don't put on the box.
kevstev 11mo ago
Is there a real source that confirms this with data? I generally like xda, but the quality of their articles is uneven and they trend towards click bait headlines that try to shock/surprise you with thin content underneath. There have been a string of "Here is the one piece of software you didn't know you needed for your NAS" and it turns out to be something extremely popular like home assistant. This article just seems to link to a series of other xda articles with no primary source. I wouldn't ever trust any single piece of hardware to store my data forever but this feels like clickbait- At one point they even state "...but you shouldn't really worry about it..."
pmarreck 11mo ago
shameless plug of my anti-bitrot tool, which I am actually enhancing with a --daemon mode currently https://github.com/pmarreck/bitrot_guard https://github.com/pmarreck/bitrot_guard
m0dest 11mo ago
So, product idea: A powered "cold storage box" for M.2 SSDs. 2 to 8 M.2 slots. Periodically, an internal computer connects one of the slots, reads every byte, waits for some period of time, then powers off. Maybe shows a little green light next to each drive when the last read was successful. Could be battery-powered.
- loeg 11mo ago
  How much are you saving vs an always-on ARM board with M.2 slots? Is it worth the pennies?
- throwaway894345 11mo ago
  > Could be battery-powered. How often does it need to run? If it could be solar powered you could probably avoid a whole bunch of complexity per unit longevity.
- boznz 11mo ago
  here's a better idea, buy a mechanical hard disk.
deleted 11mo ago
[deleted]
cobertos 11mo ago
How does one keep an SSD powered without actually mounting it or working with it? I have backups on SSDs and old drives I would like to keep somewhat live. Should I pop them in an old server? Is there an appliance that just supplies power? Is there a self-hosted thing I can monitor disks which I have 0 access usage for and don't want connected to anything but want to keep "live"
- nirui 11mo ago
  The simplest trick is just don't use SSD for long term backup, use a normal magnetic hard drive instead, those thing way lasts _longer_ (but not forever, even in human timescale). I have a HDD that was 17+ years since it last powered on. I dug it out recently to re-establish some memories, and discovered that it still reads. But of course you need to take care of them well, put them in an Anti-Static Bag or something similar, and make sure the storage environment is dry. It's not prefect, but at least you don't have to struggle that much maintaining SSDs.
  - ziml77 11mo ago
    I'm seeing threads where even for HDDs people are recommending you mount them yearly to do a full check of the data and to ensure that everything keeps moving freely.
    - lofaszvanitt 11mo ago
      Superstition....
      - akimbostrawman 11mo ago
        While unlikely solar flares or other environmental conditions could damage data over a long time.
    - procaryote 11mo ago
      regardless if it actually helps the longevity, it's probably a pretty good way to notice when you need another copy of the data. If you have your precious data on three harddrives and one starts thowing errors during your yearly check, you can get a replacement in good time
spoaceman7777 11mo ago
A solution I haven't yet seen in this thread is to buy multiple drives, and sacrifice the capacity of one of those drives to maintain single parity via a raidz1 configuration with zfs. (raidz2 or raidz3 are likely better, as you can guard against full drive failures as well, but you'd need to increase the number of drives' capacity that you're using for parity.) zfs in these filesystem-specific parity-raid implementations also auto-repairs corrupted data whenever read, and the scrub utility provides an additional tool for recognizing and correcting such issues proactively. This applies to both HDDs and SSDs. So, a good option for just about any archival use case.
- fweimer 11mo ago
  How would this work? Wouldn't all these drives start loosing data at roughly at the same time?
  - spoaceman7777 11mo ago
    Yes, but different pieces of data. The stored parity allows you to reconstruct any piece of data as long as it is only lost on one of the drives (in the single parity scenario). The odds of losing the same piece of data on multiple drives is much lower than losing any piece of data at all.
    - danparsonson 11mo ago
      But the data is not disappearing, it's corrupted - so how do you know which bits are good and which are not?
      - spoaceman7777 11mo ago
        checksums
        danparsonson 11mo ago
        Where are you storing your checksums? If the answer is 'on the corrupted drive' then what makes you think that the checksums are correct?
fsckboy 11mo ago
>unpowered SSDs slowly lose data so it's as if the data... rusts, a little bit at a time
- dsego 11mo ago
  Usually described as bit rot.
  - fsckboy 11mo ago
    was referencing the main competition to ssd's, often decried as spinning rust
stuxnet79 11mo ago
Welp, new fear unlocked. I need to move all my backups to ZFS sooner rather than later ...
hyperliner 11mo ago
[dead]
breput 11mo ago
The spinrite[0] user group has noticed some of these effects, even on in-service drives. The theory is that operating system files, which rarely change, are written and almost never re-written. So the charges begin to decay over time and while they might not be unreadable, reads for these blocks require additional error correction, which reduces performance. There have been a significant number of (anecdotal) reports that a full rewrite of the drive, which does put wear on the cells, greatly increases the overall performance. I haven't personally experienced this yet, but I do think a "every other year" refresh of data on SSDs makes sense. [0] https://www.grc.com/sr/spinrite.htm https://www.grc.com/sr/spinrite.htm
- londons_explore 11mo ago
  There are lots of other potential causes for the same effect... Eg. Data structures used for page mapping getting fragmented and therefore to access a single page written a long time ago requires checking hundreds of versions of mapping tables.
- 2WSSd-JzVM 11mo ago
  If full rewrite helps doesn't it sound like TRIM implementation in SSDs is buggy or insufficient? Or internal cell wear-maps aren't detailed enough. Anyway plenty ways it can go wrong, SSD firmware had also plenty of high profile bugs, including total bricking.
roschdal 11mo ago
Shitty Storage Device
groestl 11mo ago
A strong believe of mine: there is no storage, only communication. I hold that thought since I first heard of SRAM, and I think it applies to everything, knowledge, technology, societies, our universe in general..
- rafterydj 11mo ago
  Interesting statement. I suppose you could argue that long term archival storage is communication with a long tailed, sometimes ill-defined window for receiving the message. Few people write books they don't want anyone to read.
2rsf 11mo ago
I was in a team that wrote the firmware to handle that 15 years ago, with focus on automotive implementations where temperature might be high and access to the data is harder.
fnord77 11mo ago
well poop, I was just about to buy an 8Tb ssd to use as a backup device
lxgr 11mo ago
As far as I understand, this even applies to some seemingly read-only storage such as game cartridges, e.g. those for the Nintendo Switch. Flash storage is apparently cheaper (especially for smaller production runs) and/or higher density these days, so these cartridges just use that and make it appear ROM-like via a controller.
hosh 11mo ago
Does this also apply to thumbdrives?
- pja 11mo ago
  Yes, it applies to all flash memory. Timescales will vary depending on the fabrication type, ambient temperature etc etc.
fuzztester 11mo ago
Does the same apply to USB thumb drives, i.e. do they lose their data if not plugged in?
- zozbot234 11mo ago
  USB thumb drives (and SD cards) are bottom-of-the-barrel flash, so yes, absolutely.
  - fuzztester 11mo ago
    good to know, thanks.
EVAN1098 11mo ago
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reflexe 11mo ago
Also, FYI for the one person here who uses raw nand flash: run ubihealthd (https://lwn.net/Articles/663751/ https://lwn.net/Articles/663751/). It will trigger reads in random areas in flash, and try ti correct any errors found. Without it, the same issue as in the original article will happen (even if the device is powered on): areas in the NAND were not read for long time will have more and more errors, causing them to be non recoverable.
tensility 11mo ago
Good advice; however, past experience suggests that conventional magnetic hard drives suffer problems of stiction when left in cold storage for too long. I wouldn't trust either technology for long-term archival purposes.
leo_e 11mo ago
We learned this the hard way with "cold" backups stored in a literal safe. We treated NVMe drives like digital stone tablets. A year later, we tried to restore a critical snapshot and checksums failed everywhere. We now have a policy to power-cycle our cold storage drives every 6 months just to refresh the charge traps. It's terrifying how ephemeral "permanent" storage actually is. Tape is annoying to manage, but at least it doesn't leak electrons just sitting on a shelf.
- deltoidmaximus 11mo ago
  What does power-cycle mean in this case? I've seen this topic come up a lot on a datahoarder forum but there was never any consensus on what it would take to assure the data was refreshed because no one really knew how it worked. People would assume anything from a short power up to simply rewriting all data as possibilities. The firmware engineer responding up thread is actually the best information I've seen on this. And it kind of confirmed my suspicions. He works on enterprise drives and they run a refresh cycle as background cycle that seems to start on a random timer. I didn't see any response (yet) on how long this process takes but I think we can infer that it takes a while based on it being a background process. Probably hours or more. And this is all for an enterprise drive, I wouldn't be surprised if consumer drives have a less robust or even non-existent refresh function. I'm of the opinion that that based on the little information about some implementations of this function, the logical conclusion is you should just rewrite all of the data over again on your cold backups for the cycle. Powering it on isn't enough, even powering it on for a day might not do anything. As you said this is a pretty big drawback for uses flash as a cold backup.
- qingcharles 11mo ago
  I was talking to a lawyer recently and somehow this subject came up and he confessed he has been scanning and storing all his files onto SSDs for years which he keeps in a safe to meet a 7-year retention requirement.
- thenthenthen 11mo ago
  What is the goldielocks area here, spinning rust? My 20 year old ide hdds seem to be… ok
Barry-Perkins 11mo ago
[dead]
mghackerlady 11mo ago
This is a really good case for better file systems with built in error correction and self healing. On linux they have btrfs which kinda does this, and some support for zfs. In the BSD land we have zfs and hammer2. Does NT or Mac have anything like this? I think Mac might have some unofficial zfs support but I don't know the state that's in
- johnebgd 11mo ago
  The self healing only works if you have redundant drives. If all SSD’s are like this maybe they need alarms that sound as an onboard battery gets low to ensure someone plugs them in.
lizknope 11mo ago
I've been hearing about this for years and it makes sense theoretically but has anyone ever actually seen it? What are the errors reported? Or does the drive return bad data but reports no error? There was a guy on reddit that took about 20 cheap USB flash drives and checked 1 every 6 months. I think after 3 years nothing was bad yet. I've copied OS ISO images to USB flash drives and I know they sat for at least 2 years unused. Then I used it to install the OS and it worked perfectly fine with no errors reported. I still have 3 copies of all data and 1 of those copies is offsite but this scare about SSDs losing data is something that I've never actually seen.
- orbital-decay 11mo ago
  Of course. Cheap USB sticks in particular "spoil" pretty frequently due to firmware corruption while being stored in a drawer, this is something they're known for since the invention. I had this happen with a few. For some designs, it's possible to reflash them and they'll work again.
thomas-shelby 11mo ago
[dead]
buildbot 11mo ago
Making sure all your important data can be read and is checked at read is like zfs scrubs sole purpose. Seems like at least a monthly scrub is a very good idea for SSDs.
kevin-scott21 11mo ago
[dead]
KPGv2 11mo ago
> SSDs have all but replaced hard drives when it comes to primary storage. Really? I could have sworn that primary storage was the one place they weren't going to replace HDDs. Aren't they more of a thing for cache? I've aged and busied myself beyond keeping track of this stuff anymore. I'm going to buy a packable NAS in the next couple months and be done with it. Hopefully ZFS since apparently that's the bee's knees and I won't have to think about RAIDs anymore.
carra 11mo ago
We may be facing a grim situation in a few years because of this. Right now most consumer-grade storage is flash memory, and all of it suffers from this problem. SSDs, pendrives, SD cards, Compact Flash... Apparently games for the Nintendo 3DS and PS Vita are already suffering from this, and people losing photos in faulty SDs is hardly news.
paranoidrobot 11mo ago
For years I've been collecting a slowly growing pile of old drives from old devices as I had replaced them. I finally decided to do something about them and got myself a USB to IDE/SATA adapter and spent a week or so duplicating them so I could check if there was anything worthwhile to keep, before destroyig and sending them to an e-waste recycler. Some of those drives had been sitting around since early 2000. All except two of the mechanical drives just fired up and worked fine. One won't power on at all. One powers up, but reading from some sectors just results in failures. But the SSDs are another story. All blank/empty for any that were more than a few years old. Even though I know some were pulled from working machines.
whoisthemachine 11mo ago
Yes, for the same reason we don't have any perpetual motion machines.
asdefghyk 11mo ago
I note , CHEMICAL reactions proceed faster with heat. So this why data retention is longer if device is in "...cold storage.." (This situation is also know with old photographic film , if stored in low temperatures it can last cira 100 years, but if stored at much higher room? temperatures , the film deterioration is much faster ) In SSD drives digital bits are stored as a electrical charge amount for each "cell". I suspect these cells have been decreased in size to provide much larger numerically increased SSD storage amounts. The decreased cell size means the charge decreases below needed amount faster and ssd becomes unreliable. MORE IMPORTANTLY - I also contend the SSD CHIP DESIGNERS would have/SHOULD HAVE been aware of this size effect and the decreased SSD reliability was not publicised OR specified for the product data sheets. Presently I'm looking for articales that prove my suspicions or assertions
asdefghyk 11mo ago
From the above linked articale "... Your SSD data isn't as permanent as you think Even the cheapest SSDs, say those with QLC NAND, can safely store data for about a year of being completely unpowered. More expensive TLC NAND can retain data for up to 3 years, while MLC and SLC NAND are good for 5 years and 10 years of unpowered storage, respectively. ..." RE "...QLC NAND, can safely store data for about a year of being completely unpowered...." QLC Nand only reliably stores data for only a year . This would be within the warranty period for some products. This information should be more clearly shown to product purchasers.
dusted 11mo ago
This is true, but it is generally true. Even for UV-EPROMs the retention time can be as low as a 25 years, if kept warm, even with the window sealed correctly. Magnetic drives are quite a lot better, around 50 years. CD-RWs are somewhat wider in their stability, I have ~20 year old discs that are becoming unreadable because the actual foil is delaminating from the plastic disc. Meanwhile I have ~40 year old DS-DD floppies that are still fully readable even though their medium is in physical contact with the read/write heads (although here, again, storage conditions and especially the different brands/batches seem to make a difference).

770 points by amichail 11mo ago

xda-developers..... reliable source. nonetheless time to ask the ssd makers whats their take on this. they have support,time to write to them.

paulkrush 11mo ago

I had to search around and feel like a dork not knowing this. I have my data backed up, but I keep the SSDs because it's nice to have the OS running like it was... I guess I need to be cloning the drives to ISOs and storing on spinning rust.

dpoloncsak 11mo ago
I could be wrong, but I believe the general consensus is along the lines of "SSDs for in-use data, it's quicker and wants to be powered on often. HDDs for long-term storage, as they don't degrade when not in use nearly as fast as SSDs do.
- joezydeco 11mo ago
  I've been going through stack of external USB drives with laptop disks in them. They're all failing in some form or another. I'm going to have to migrate it all to a NAS with server-class drives I guess
  - Yokolos 11mo ago
    At the very least, you can usually still get the data off of them. Most SSDs I've encountered with defects failed catastrophically, rendering the data completely inaccessible.
- PunchyHamster 11mo ago
  I'd imagine HDDs also don't like not spinning for years(as mechanical elements generally like to be used from time to time). But at least platters itself are intact
pluralmonad 11mo ago
I learned this when both my old laptops would no longer boot after extended off power time (couple years). They were both stored in a working state and later both had SSDs that were totally dead.
- justin66 11mo ago
  Were the SSDs toasted, or were you able to reinstall to them?
  - pluralmonad 11mo ago
    D.E.A.D. Had to replace them.
gosub100 11mo ago
or you could power them on 1-2x /year.
- ggm 11mo ago
  Power them on and run something to exercise the read function over every bit. Thats why a ZFS filesystem integrity check/scrub is the useful model. I'm unsure if dd if=/the/disk of=/dev/null does the read function.
  - fragmede 11mo ago
    why would it not? it's a low level tool to do exactly that. you could "of" it to somewhere else if you're worried it's not. I like to | hexdump -C, on an xterm set to a green font on a black background for a real matrix movie kind of feel.

sevensor 11mo ago

Flash is programmed by increasing the probability that electrons will tunnel onto the floating gate and erased by increasing the probability they will tunnel back off. Those probabilities are never zero. Multiply that by time and the number of cells, and the probability you don’t end up with bit errors gets quite low. The difference between slc and mlc is just that mlc has four different program voltages instead of two, so reading back the data you have to distinguish between charge levels that are closer together. Same basic cell design. Honestly I can’t quite believe mlc works at all, let alone qlc. I do wonder why there’s no way to operate qlc as if it were mlc, other than the manufacturer not wanting to allow it.

Someone 11mo ago
> I do wonder why there’s no way to operate qlc as if it were mlc, other than the manufacturer not wanting to allow it. You can run an error-correcting code on top of the regular blocks of memory, storing, for example (really an example; I don’t know how large the ‘blocks’ that you can erase are in flash memory), 4096 bits in every 8192 bits of memory, and recovering those 4096 bits from each block of 8192 bits that you read in the disk driver. I think that would be better than a simple “map low levels to 0, high levels to 1” scheme.
bobmcnamara 11mo ago
> I do wonder why there’s no way to operate qlc as if it were mlc, other than the manufacturer not wanting to allow it. Loads of drives do this(or SLC) internally. Though it would be handy if a physical format could change the provisioning at the kernel accessible layer.
em500 11mo ago
> Honestly I can’t quite believe mlc works at all, let alone qlc. I do wonder why there’s no way to operate qlc as if it were mlc, other than the manufacturer not wanting to allow it. Manufacturers often do sell such pMLC or pSLC (p = pseudo) cells as "high endurance" flash.
testartr 11mo ago
the market demands mostly higher capacity tlc/qlc works just fine, it's really difficult to consume the erase cycles unless you really are writing 24/7 to the disk at hundred of megabytes a second

brian-armstrong 11mo ago

Powering the SSD on isn't enough. You need to read every bit occasionally in order to recharge the cell. If you have them in a NAS, then using a monthly full volume check is probably sufficient.

Izkata 11mo ago
Huh. I wonder if this is why I'd sometimes get random corruption on my laptop's SSD. I'd reboot after a while and fsck would find issues in random files I haven't touched in a long time.
- formerly_proven 11mo ago
  Unless your setup is a very odd Linux box, fsck will never check the consistency of file contents.
  - suspended_state 11mo ago
    But metadata is data too, right? I guess the next question is, would it be possible for parts of the FS metadata to remain untouched for a time long enough for the SSD data corruption process to occur.
  - Izkata 11mo ago
    It found problems in the tree - lost files, wrong node counts, other stuff - which led to me finding files that didn't match previous backups (and when opened were obviously corrupted, like the bottom half of an image being just noise). Once I found this was a problem I've also caught ones that couldn't be read (IOError) that fsck would delete on the next run. I may not have noticed had fsck not alerted me something was wrong.
  - giantrobot 11mo ago
    A ZFS scrub (default scheduled monthly) will do it.
- brian-armstrong 11mo ago

formerly_proven 11mo ago

> Even the cheapest SSDs, say those with QLC NAND, can safely store data for about a year of being completely unpowered. More expensive TLC NAND can retain data for up to 3 years, while MLC and SLC NAND are good for 5 years and 10 years of unpowered storage, respectively. This is somewhat confused writing. Consumer SSDs usually do not have a data retention spec, even in this very detailed Micron datasheet you won't find it: https://advdownload.advantech.com/productfile/PIS/96FD25-S2TB-MX/file/96FD25-S2TB-MX_datasheet20220308104755.PDF https://advdownload.advantech.com/productfile/PIS/96FD25-S2T... Meanwhile the data retention spec for enterprise SSDs is at the end of their rated life, which is usually a DPWD/TBW intensity you won't reach in actual use anyway - that's where numbers like "3 months @ 50 °C" or whatever come from. In practice, SSDs don't tend to loose data over realistic time frames. Don't hope for a "guaranteed by design" spec on that though, some pieces of silicon are more equal than others.

Yokolos 11mo ago
Any given TBW/DWPD values are irrelevant for unpowered data retention. Afaik, nobody gives these values in their datasheet and I'm wondering where their numbers are from, because I've never seen anything official. At this point I'd need to be convinced that the manufacturers even know themselves internally, because it's never been mentioned by them and it seems to be outside the intended use cases for SSDs
- formerly_proven 11mo ago
  Example: https://www.ssd.group/wp-content/uploads/2022/07/PM1733-25-SSD-Datasheet_v1.3_for-General.pdf https://www.ssd.group/wp-content/uploads/2022/07/PM1733-25-S... > Component Design Life 5 years > TBW 14 PB for 7.68 TB drives > Data Retention 3 months And then 2.7.3 explains that this number applies for 40 °C ambient, not the operating/non-operating range (up to 85 °C).
  - Yokolos 11mo ago
    That's literally just the JEDEC spec.

bossyTeacher 11mo ago

This is why I would rather pay someone a couple of dollars per year to handle all this for me. If need be pay two providers to have a backup.

loloquwowndueo 11mo ago
Who do you pay for this? (To rephrase : which cloud storage vendors do you use?) interested in the $2/month price point :)
- ggm 11mo ago
  tell me about this $2/week filestore option. I'm interested.
  - 867-5309 11mo ago
    continuing the bizarre trend, I'm here for the $2/day deal
    - topato 11mo ago
      I'D love to be paying $2/minute!
    - bigstrat2003 11mo ago
      That would be Tarsnap. Cool product and the owner is a good dude, but good Lord is it expensive. I would love to support him but just can't afford it.
- PunchyHamster 11mo ago
  Backblaze B2 is $6TB/mo, so if you have around 300GB... stuff like restic or kopia backups nicely to it
  - markhahn 11mo ago
    $72/yr is somewhere around 3x purchase price (per year). BB seems to be pretty smart about managing their exposure, infrastructure overhead, etc.

traceroute66 11mo ago

I assume this blog is a re-hash of the JDEC retention standards[1]. The more interesting thing to note from those standards is that the required retention period differs between "Client" and "Enterprise" category. Enterprise category only has power-off retention requirement of 3 months. Client category has power-off retention requirement of 1 year. Of course there are two sides to every story... Enterprise category standard has a power-on active use of 24 hours/day, but Client category only intended for 8 hours/day. As with many things in tech.... its up to the user to pick which side they compromise on. [1]https://files.futurememorystorage.com/proceedings/2011/20110810_T1B_Cox.pdf https://files.futurememorystorage.com/proceedings/2011/20110...

throw0101a 11mo ago
> I assume this blog is a re-hash of the JDEC retention standards[1]. Specifically in JEDEC JESD218. (Write endurance in JESD219.)
tcfhgj 11mo ago
With 1 year power-off retention you still loose data, so still a compromise on data retention
- deleted 11mo ago
  [deleted]
Springtime 11mo ago
In the longer JEDEC overview document[1] it explains that in the ideal 'direct' testing method retention testing is only performed after the endurance testing. Which is only after the drive has had its max spec'd TBW written to it. While if the endurance testing would exceed 1000 hours an extrapolated approach can be used to stress below the TBW but using accelerated techniques (including capping the max writable blocks to increase wear on the same areas). Which is less dramatic than the retention values seem at first and than what gets communicated in articles I've seen. Even in the OP's linked article it takes a comment to also highlight this, while the article itself only cites its own articles that contain no outside links or citations. [1] https://www.jedec.org/sites/default/files/Alvin_Cox%20%5BCompatibility%20Mode%5D_0.pdf https://www.jedec.org/sites/default/files/Alvin_Cox%20%5BCom...

testartr 11mo ago

what is the exact protocol to "recharge" an ssd which was offline for months? do I just plug it in and let the computer on for a few minutes? does it needs to stay on for hours? do I need to run a special command or TRIM it?

PunchyHamster 11mo ago
I'd imagine full read of the whole device might trigger any self-preservation, but I'd also imagine it's heavily dependent on manufacturer and firmware
PaulKeeble 11mo ago
We really don't know. One thing I wish some of these sites would do is actually test how long it takes for the drives to decay and also do a retest after they have been left powered for say 10 minutes to an hour, read completely, written to a bit etc and see if they can determine what a likely requirement is. The problem is the test will take years, be out of date by the time its released and new controllers will be out with potentially different needs/algorithms.
- unsnap_biceps 11mo ago
  There was one guy who tested this https://www.tomshardware.com/pc-components/storage/unpowered-ssd-endurance-investigation-finds-severe-data-loss-and-performance-issues-reminds-us-of-the-importance-of-refreshing-backups https://www.tomshardware.com/pc-components/storage/unpowered... The data on this SSD, which hadn't been used or powered up for two years, was 100% good on initial inspection. All the data hashes verified, but it was noted that the verification time took a smidgen longer than two years previously. HD Sentinel tests also showed good, consistent performance for a SATA SSD. Digging deeper, all isn't well, though. Firing up Crystal Disk Info, HTWingNut noted that this SSD had a Hardware ECC Recovered value of over 400. In other words, the disk's error correction had to step in to fix hundreds of data-based parity bits. ... As the worn SSD's data was being verified, there were already signs of performance degradation. The hashing audit eventually revealed that four files were corrupt (hash not matching). Looking at the elapsed time, it was observed that this operation astonishingly took over 4x longer, up from 10 minutes and 3 seconds to 42 minutes and 43 seconds. Further investigations in HD Sentinel showed that three out of 10,000 sectors were bad and performance was 'spiky.' Returning to Crystal Disk Info, things look even worse. HTWingNut notes that the uncorrectable sectors count went from 0 to 12 on this drive, and the hardware ECC recovered value went from 11,745 before to 201,273 after tests on the day.

BaardFigur 11mo ago

I don't use my drive much. I still boot it up snd write some data, just not the long term one. Am I in risk?

zozbot234 11mo ago
AIUI, informal tests have demonstrated quite a bit of data corruption in Flash drives that are literally so worn out that they might as well be about to fail altogether - well beyond any manufacturer's actual TBW specs - but not otherwise, least of all in new drives that are only written once over for the test. It seems that if you don't wear out your drive all that much you'll have far less to worry about.
- userbinator 11mo ago
  No, even drives written once have started showing a rise in (correctable) errors after 2 years: https://news.ycombinator.com/item?id=43739028 https://news.ycombinator.com/item?id=43739028
  - zozbot234 11mo ago
    That's a slight rise in ECC which is entirely expected. Flash storage can be expected to rely on error correction as part of normal functioning; it's not an abnormal condition.
    - userbinator 11mo ago
      Bit errors occurring after only 2 years, on flash that has been written to once, is not good at all.

yapyap 11mo ago

good to know but apart from some edge cases this doesnt matter that much

dale_glass 11mo ago

So on the off-chance that there's a firmware engineer in here, how does this actually work? Like does a SSD do some sort of refresh on power-on, or every N hours, or you have to access the specific block, or...? What if you interrupt the process, eg, having a NVMe in an external case that you just plug once a month for a few minutes to just use it as a huge flash drive, is that a problem? What about the unused space, is a 4 TB drive used to transport 1 GB of stuff going to suffer anything from the unused space decaying? It's all very unclear about what all of this means in practice and how's an user supposed to manage it.

zozbot234 11mo ago
Typically unused empty space is a good thing, as it will allow drives to run in MLC or SLC mode instead of their native QLC. (At least, this seems to be the obvious implication from performance testing, given the better performance of SLC/MLC compared to QLC.) And the data remanence of SLC/MLC can be expected to be significantly better than QLC.
- gruez 11mo ago
  >as it will allow drives to run in MLC or SLC mode instead of their native QLC That depends on the SSD controller implementation, specifically whether it proactively moves stuff from the SLC cache to the TLC/QLC area. I expect most controllers to do this, given that if they don't, the drive will quickly lose performance as it fills up. There's basically no reason not proactively move stuff over.
  - kasabali 11mo ago
    Cheap DRAM-less controllers usually wait until the drive is almost full to start folding. And then they'll only be folding just enough to free up some space. Most benchmark results are consistent with this behavior.
fairfeather 11mo ago
SSD firmware engineer here. I work on enterprise stuff, so ymmv on consumer grade internals. Generally, the data refresh will all happen in the background when the system is powered (depending on the power state). Performance is probably throttled during those operations, so you just see a slightly slower copy while this is happening behind the scenes. The unused space decaying is probably not an issue, since the internal filesystem data is typically stored on a more robust area of media (an SLC location) which is less susceptible to data loss over time. As far as how a user is supposed to manage it, maybe do an fsck every month or something? Using an SSD like that is probably ok most of the time, but might not be super great as a cold storage backup.

tzs 11mo ago

What about powered SSDs that contain files that are rarely read? My desktop computer is generally powered except when there is a power failure, but among the million+ files on its SSD there are certainly some that I do not read or write for years. Does the SSD controller automatically look for used blocks that need to have their charge refreshed and do so, or do I need to periodically do something like "find / -type f -print0 | xargs -0 cat > /dev/null" to make sure every file gets read occasionally?

JensenTorp 11mo ago
I also need an answer to this.
- dboreham 11mo ago
  It's fine. But the whole drive can turn to dust at any time, of course.
  - danparsonson 11mo ago
    I stopped buying cursed second-hand drives for exactly this problem.
    - formerly_proven 11mo ago
      The supply chain got you covered and will randomly hand you inofficially-refurbished drives as new ones ;)
seg_lol 11mo ago
You should absolutely be doing a full block read of your disk, dd if=/dev/disk of=/dev/null every couple weeks
- topato 11mo ago
  pretty accurate username

jcynix 11mo ago

Hmm, so what about these modern high density hard drives which store track parameters for their servos in on-board flash (aka OptiNAND)? Do we get "spinning rust" which might loose the information where exactly it stored the data? https://blog.westerndigital.com/optinand-explained/ https://blog.westerndigital.com/optinand-explained/

binaryturtle 11mo ago
I wonder too. I don't trust SSDs/ flash for my archives, hence I'm stuck on max. 18TB drives atm.
markhahn 11mo ago
shouldn't really be a problem, since the capacity required for this use is so low. the real issue here is QLC in which the flash cell's margins are being squeezed enthusiastically...
userbinator 11mo ago
I think you're talking about two different things; "adaptives" are usually stored in EEPROM or the MCU's NOR flash, which is basically better-than-SLC levels of reliability, especially as they're written once and treated as ROM after that. OptiNAND is a "SSHD" and thus has the same concerns with retention as an SSD. https://en.wikipedia.org/wiki/Hybrid_drive https://en.wikipedia.org/wiki/Hybrid_drive

storus 11mo ago

I thought that was an ancient issue with Samsung 740? I had that one and it was slowly losing speed when unpowered due to an accumulation of errors and rewriting the individual sectors once for the whole drive made it work fine for a year.

TacticalCoder 11mo ago

So basically if you like to put SSDs on shelves (for offline backups), you should read them from scratch once in a while? I rotate religiously my offline SSDs and HDDs (I store backups on both SSDs and HDDs): something like four at home (offline onsite) and two (one SSD, one HDD) in a safe at the bank (offline offsite). Every week or so I rsync (a bit more advanced than rsync in that I wrap rsync in a script that detects potential bitrot using a combination of an rsync "dry-run" and known good cryptographic checksums before doing the actual rsync [1]) to the offline disks at home and then every month or so I rotate by swapping the SSD and HDD at the bank with those at home. Maybe I should add to the process, for SSDs, once every six months: ... $ dd if=/dev/sda | xxhsum I could easily automate that in my backup'ing script by adding a file lastknowddtoxxhash.txt containing the date of the last full dd to xxhsum, verifying that, and then asking, if a SSD is detected (I take it on a HDD it doesn't matter), if a full read to hash should be done. Note that I'm already using random sampling on files containing checksums in their name, so I'm already verifying x% of the files anyway. So I'd probably be detecting a fading SSD quite easily. Additionally I've also got a server with ZFS in mirroring so this, too, helps keep a good copy of the data. FWIW I still have most of the personal files from my MS-DOS days so I must be doing something correctly when it comes to backing up data. But yeah: adding a "dd to xxhsum" of the entire disks once every six months in my backup'ing script seems like a nice little addition. Heck, I may go hack that feature now. [1] otherwise rsync shall happily trash good files with bitrotten ones

nubinetwork 11mo ago

I've got some old SSDs just to test this myself, the old 256gb corsairs I tested previously were fine after a year and a half, but I might have misplaced them...(they only had 10% write life left, so no huge loss) the 512gb samsungs on my desk should be getting pretty ripe soon though, I'll have to check those too.

canadiantim 11mo ago

What is the best way to store data for a long time then?

markhahn 11mo ago
all the major players say "tape". (but that's partly for practical issues like scaling and history)
- deleted 11mo ago
  [deleted]
- octorian 11mo ago
  And yet nobody wants to actually offer a tape-based solution that's practical, easy to get, holds enough data, and doesn't cost a blithering fortune. Even if you are willing to spend that small fortune, good luck actually getting all the parts together without enterprise contracts.
schneehertz 11mo ago
Depending on your time requirements, carving it into a stone tablet is generally a good choice

dboreham 11mo ago

Quick note to not store any valuable data on a single drive. And when you store it on two drives, don't use the same kind of drive. (Speaking from bitter experience using spinning drives in servers that had a firmware bug where they all died at the time number of seconds of power-on time).

burnt-resistor 11mo ago
That's kicking the can down the road for double the cost. Only a backup on spinning rust is actually a backup. Furthermore, replication isn't a backup.

userbinator 11mo ago

One key point about retention which is not often mentioned, and indeed neither does this article, is that retention is inversely proportional to program/erase cycles and decreases exponentially with increasing temperature. Hence why retention specs are usually X amount of time after Y cycles at Z temperature. Even a QLC SSD that has only been written to once, and kept in a freezer at -40, may hold data for several decades. Manufacturers have been playing this game with DWPD/TBW numbers too --- by reducing the retention spec, they can advertise a drive as having a higher endurance with the exact same flash. But if you compare the numbers over the years, it's clear that NAND flash has gotten significantly worse; the only thing that has gone up, multiplicatively, is capacity, while endurance and rentention have both gone down by a few orders of magnitude. For a long time, 10 years after 100K cycles was the gold standard of SLC flash. Now we are down to several months after less than 1K cycles for QLC.

RachelF 11mo ago
Endurance going down is hardly a surprise given that the feature size has gone down too. The same goes for logic and DRAM memory. I suspect that 2035 years time, hardware from 2010 will work, while that from 2020 will be less reliable.
- Dylan16807 11mo ago
  As far as I'm aware flash got a bit of a size boost when it went 3D and hasn't shrunk much since then. If you use the same number of bits per cell, I don't know if I would expect 2010 and 2020 or 2025 flash to vary much in endurance. For logic and DRAM the biggest factors are how far they're being pushed with voltage and heat, which is a thing that trends back and forth over the years. So I could see that go either way.
- lotrjohn 11mo ago
  Completely anecdotal, and mostly unrelated, but my NES from 1990 is still going strong. Two PS3’s that I have owned simply broke. CRTs from 1994 and 2002 still going strong. LCD tvs from 2012 and 2022 just went kaput for no reason. Old hardware rocks.

cosmic_cheese 11mo ago

Is there any type of flash-based storage (preferably accessible to end users) that focuses on long term data retention? If not, that feels like a substantial hole in the market. Non-flash durable storage tend to be annoying or impractical for day to day use. I want to be able to find a 25 year old SD card hiding in some crevice and unearth an unintentional time capsule, much like how one can pick up 20+ year old MiniDiscs and be able to play the last thing their former owners recorded to them perfectly.

55873445216111 11mo ago
Yes, NOR Flash guarantees 20 years data retention. It's about $30/GiB.
tensility 11mo ago
There are also expensive high-grade SLC NAND flash chips available that offer significantly higher retention time than the cheaper commodity channel TLC NAND (i.e. 10 years versus 3 years). In general, though, whether NAND or NOR, the fundamental way that flash works is by creating an isolated voltage charge for each bit (or several bits, for TLC), making it effectively a vast grid of very tiny batteries. Like all batteries, no matter how well-stored, they will eventually leak energy to the point where the voltage levels change enough to matter. Further, it's not enough to simply make power available to this grid since the refresh of the cells requires active management by a nand controller chip and its associated software stack.

coppsilgold 11mo ago

My scrub script: dd if=$1 of=/dev/null iflag=direct bs=16M status="progress" smartctl -a $1 If someone wants to properly study SSD data-retention they could encrypt the drive using plain dm-crypt and fill the encrypted volume with zeroes and check at some time point afterwards to see if there are any non-zero blocks. This is an accessible way (no programming involved) to let you write random data to the SSD and save it without actually saving the entire thing - just the key. It will also ensure maximum variance in charge levels of all the cells. Will also prevent the SSD from potentially playing tricks such as compression.

burnt-resistor 11mo ago

Not having a (verified) backup is driving without a seatbelt.

Wowfunhappy 11mo ago

> But, most people don't need to worry about it. [...] You should always have a backup anyway. [...] Backing up your data is the simplest strategy to counteract the limitations of storage media. Having multiple copies of your data on different types of storage ensures that any unexpected incidents protect your data from vanishing forever. This is exactly what the 3-2-1 backup rule talks about: 3 copies of data on at least 2 different storage media, with 1 copy stored off-site. Um. Backups seem like exactly why I might have data on an unpowered SSD. I use HDDs right now because they're cheaper, but that might not be true some day. Also, I would expect someone less technically inclined than I am to just use whatever they have lying around, which may well be an SSD.

jollyllama 11mo ago
Yeah. That part was so out of touch, I have to wonder who they're carrying water for. Most people backup their data? What planet does the author live on?

behringer 11mo ago

The article implies this is not a concern for "regular" people. That is absolutely false. How many people get their family photos when they finally decide to recycle that 15 year old PC in the basement? How many people have a device that they may only power up ever few years, like on vacation. In fact, I have a device that I've only used on rare occasions these days (an arcade machine) that now I suspect I'll have to reinstall since It's been 2 or 3 years since I've last used it. This is a pretty big deal that they don't put on the box.

kevstev 11mo ago

Is there a real source that confirms this with data? I generally like xda, but the quality of their articles is uneven and they trend towards click bait headlines that try to shock/surprise you with thin content underneath. There have been a string of "Here is the one piece of software you didn't know you needed for your NAS" and it turns out to be something extremely popular like home assistant. This article just seems to link to a series of other xda articles with no primary source. I wouldn't ever trust any single piece of hardware to store my data forever but this feels like clickbait- At one point they even state "...but you shouldn't really worry about it..."

pmarreck 11mo ago

shameless plug of my anti-bitrot tool, which I am actually enhancing with a --daemon mode currently https://github.com/pmarreck/bitrot_guard https://github.com/pmarreck/bitrot_guard

m0dest 11mo ago

So, product idea: A powered "cold storage box" for M.2 SSDs. 2 to 8 M.2 slots. Periodically, an internal computer connects one of the slots, reads every byte, waits for some period of time, then powers off. Maybe shows a little green light next to each drive when the last read was successful. Could be battery-powered.

loeg 11mo ago
How much are you saving vs an always-on ARM board with M.2 slots? Is it worth the pennies?
throwaway894345 11mo ago
> Could be battery-powered. How often does it need to run? If it could be solar powered you could probably avoid a whole bunch of complexity per unit longevity.
boznz 11mo ago
here's a better idea, buy a mechanical hard disk.

deleted 11mo ago

[deleted]

cobertos 11mo ago

How does one keep an SSD powered without actually mounting it or working with it? I have backups on SSDs and old drives I would like to keep somewhat live. Should I pop them in an old server? Is there an appliance that just supplies power? Is there a self-hosted thing I can monitor disks which I have 0 access usage for and don't want connected to anything but want to keep "live"

nirui 11mo ago
The simplest trick is just don't use SSD for long term backup, use a normal magnetic hard drive instead, those thing way lasts _longer_ (but not forever, even in human timescale). I have a HDD that was 17+ years since it last powered on. I dug it out recently to re-establish some memories, and discovered that it still reads. But of course you need to take care of them well, put them in an Anti-Static Bag or something similar, and make sure the storage environment is dry. It's not prefect, but at least you don't have to struggle that much maintaining SSDs.
- ziml77 11mo ago
  I'm seeing threads where even for HDDs people are recommending you mount them yearly to do a full check of the data and to ensure that everything keeps moving freely.
  - lofaszvanitt 11mo ago
    Superstition....
    - akimbostrawman 11mo ago
      While unlikely solar flares or other environmental conditions could damage data over a long time.
  - procaryote 11mo ago
    regardless if it actually helps the longevity, it's probably a pretty good way to notice when you need another copy of the data. If you have your precious data on three harddrives and one starts thowing errors during your yearly check, you can get a replacement in good time

spoaceman7777 11mo ago

A solution I haven't yet seen in this thread is to buy multiple drives, and sacrifice the capacity of one of those drives to maintain single parity via a raidz1 configuration with zfs. (raidz2 or raidz3 are likely better, as you can guard against full drive failures as well, but you'd need to increase the number of drives' capacity that you're using for parity.) zfs in these filesystem-specific parity-raid implementations also auto-repairs corrupted data whenever read, and the scrub utility provides an additional tool for recognizing and correcting such issues proactively. This applies to both HDDs and SSDs. So, a good option for just about any archival use case.

fweimer 11mo ago
How would this work? Wouldn't all these drives start loosing data at roughly at the same time?
- spoaceman7777 11mo ago
  Yes, but different pieces of data. The stored parity allows you to reconstruct any piece of data as long as it is only lost on one of the drives (in the single parity scenario). The odds of losing the same piece of data on multiple drives is much lower than losing any piece of data at all.
  - danparsonson 11mo ago
    But the data is not disappearing, it's corrupted - so how do you know which bits are good and which are not?
    - spoaceman7777 11mo ago
      checksums
      - danparsonson 11mo ago
        Where are you storing your checksums? If the answer is 'on the corrupted drive' then what makes you think that the checksums are correct?

fsckboy 11mo ago

>unpowered SSDs slowly lose data so it's as if the data... rusts, a little bit at a time

dsego 11mo ago
Usually described as bit rot.
- fsckboy 11mo ago
  was referencing the main competition to ssd's, often decried as spinning rust

stuxnet79 11mo ago

Welp, new fear unlocked. I need to move all my backups to ZFS sooner rather than later ...

hyperliner 11mo ago

[dead]

breput 11mo ago

The spinrite[0] user group has noticed some of these effects, even on in-service drives. The theory is that operating system files, which rarely change, are written and almost never re-written. So the charges begin to decay over time and while they might not be unreadable, reads for these blocks require additional error correction, which reduces performance. There have been a significant number of (anecdotal) reports that a full rewrite of the drive, which does put wear on the cells, greatly increases the overall performance. I haven't personally experienced this yet, but I do think a "every other year" refresh of data on SSDs makes sense. [0] https://www.grc.com/sr/spinrite.htm https://www.grc.com/sr/spinrite.htm

londons_explore 11mo ago
There are lots of other potential causes for the same effect... Eg. Data structures used for page mapping getting fragmented and therefore to access a single page written a long time ago requires checking hundreds of versions of mapping tables.
2WSSd-JzVM 11mo ago
If full rewrite helps doesn't it sound like TRIM implementation in SSDs is buggy or insufficient? Or internal cell wear-maps aren't detailed enough. Anyway plenty ways it can go wrong, SSD firmware had also plenty of high profile bugs, including total bricking.

roschdal 11mo ago

Shitty Storage Device

groestl 11mo ago

A strong believe of mine: there is no storage, only communication. I hold that thought since I first heard of SRAM, and I think it applies to everything, knowledge, technology, societies, our universe in general..

rafterydj 11mo ago
Interesting statement. I suppose you could argue that long term archival storage is communication with a long tailed, sometimes ill-defined window for receiving the message. Few people write books they don't want anyone to read.

2rsf 11mo ago

I was in a team that wrote the firmware to handle that 15 years ago, with focus on automotive implementations where temperature might be high and access to the data is harder.

fnord77 11mo ago

well poop, I was just about to buy an 8Tb ssd to use as a backup device

lxgr 11mo ago

As far as I understand, this even applies to some seemingly read-only storage such as game cartridges, e.g. those for the Nintendo Switch. Flash storage is apparently cheaper (especially for smaller production runs) and/or higher density these days, so these cartridges just use that and make it appear ROM-like via a controller.

hosh 11mo ago

Does this also apply to thumbdrives?

pja 11mo ago
Yes, it applies to all flash memory. Timescales will vary depending on the fabrication type, ambient temperature etc etc.

fuzztester 11mo ago

Does the same apply to USB thumb drives, i.e. do they lose their data if not plugged in?

zozbot234 11mo ago
USB thumb drives (and SD cards) are bottom-of-the-barrel flash, so yes, absolutely.
- fuzztester 11mo ago
  good to know, thanks.

EVAN1098 11mo ago

[dead]

reflexe 11mo ago

Also, FYI for the one person here who uses raw nand flash: run ubihealthd (https://lwn.net/Articles/663751/ https://lwn.net/Articles/663751/). It will trigger reads in random areas in flash, and try ti correct any errors found. Without it, the same issue as in the original article will happen (even if the device is powered on): areas in the NAND were not read for long time will have more and more errors, causing them to be non recoverable.

tensility 11mo ago

Good advice; however, past experience suggests that conventional magnetic hard drives suffer problems of stiction when left in cold storage for too long. I wouldn't trust either technology for long-term archival purposes.

leo_e 11mo ago

We learned this the hard way with "cold" backups stored in a literal safe. We treated NVMe drives like digital stone tablets. A year later, we tried to restore a critical snapshot and checksums failed everywhere. We now have a policy to power-cycle our cold storage drives every 6 months just to refresh the charge traps. It's terrifying how ephemeral "permanent" storage actually is. Tape is annoying to manage, but at least it doesn't leak electrons just sitting on a shelf.

deltoidmaximus 11mo ago
What does power-cycle mean in this case? I've seen this topic come up a lot on a datahoarder forum but there was never any consensus on what it would take to assure the data was refreshed because no one really knew how it worked. People would assume anything from a short power up to simply rewriting all data as possibilities. The firmware engineer responding up thread is actually the best information I've seen on this. And it kind of confirmed my suspicions. He works on enterprise drives and they run a refresh cycle as background cycle that seems to start on a random timer. I didn't see any response (yet) on how long this process takes but I think we can infer that it takes a while based on it being a background process. Probably hours or more. And this is all for an enterprise drive, I wouldn't be surprised if consumer drives have a less robust or even non-existent refresh function. I'm of the opinion that that based on the little information about some implementations of this function, the logical conclusion is you should just rewrite all of the data over again on your cold backups for the cycle. Powering it on isn't enough, even powering it on for a day might not do anything. As you said this is a pretty big drawback for uses flash as a cold backup.
qingcharles 11mo ago
I was talking to a lawyer recently and somehow this subject came up and he confessed he has been scanning and storing all his files onto SSDs for years which he keeps in a safe to meet a 7-year retention requirement.
thenthenthen 11mo ago
What is the goldielocks area here, spinning rust? My 20 year old ide hdds seem to be… ok

Barry-Perkins 11mo ago

[dead]

mghackerlady 11mo ago

This is a really good case for better file systems with built in error correction and self healing. On linux they have btrfs which kinda does this, and some support for zfs. In the BSD land we have zfs and hammer2. Does NT or Mac have anything like this? I think Mac might have some unofficial zfs support but I don't know the state that's in

johnebgd 11mo ago
The self healing only works if you have redundant drives. If all SSD’s are like this maybe they need alarms that sound as an onboard battery gets low to ensure someone plugs them in.

lizknope 11mo ago

I've been hearing about this for years and it makes sense theoretically but has anyone ever actually seen it? What are the errors reported? Or does the drive return bad data but reports no error? There was a guy on reddit that took about 20 cheap USB flash drives and checked 1 every 6 months. I think after 3 years nothing was bad yet. I've copied OS ISO images to USB flash drives and I know they sat for at least 2 years unused. Then I used it to install the OS and it worked perfectly fine with no errors reported. I still have 3 copies of all data and 1 of those copies is offsite but this scare about SSDs losing data is something that I've never actually seen.

orbital-decay 11mo ago
Of course. Cheap USB sticks in particular "spoil" pretty frequently due to firmware corruption while being stored in a drawer, this is something they're known for since the invention. I had this happen with a few. For some designs, it's possible to reflash them and they'll work again.

thomas-shelby 11mo ago

[dead]

buildbot 11mo ago

Making sure all your important data can be read and is checked at read is like zfs scrubs sole purpose. Seems like at least a monthly scrub is a very good idea for SSDs.

kevin-scott21 11mo ago

[dead]

KPGv2 11mo ago

> SSDs have all but replaced hard drives when it comes to primary storage. Really? I could have sworn that primary storage was the one place they weren't going to replace HDDs. Aren't they more of a thing for cache? I've aged and busied myself beyond keeping track of this stuff anymore. I'm going to buy a packable NAS in the next couple months and be done with it. Hopefully ZFS since apparently that's the bee's knees and I won't have to think about RAIDs anymore.

carra 11mo ago

We may be facing a grim situation in a few years because of this. Right now most consumer-grade storage is flash memory, and all of it suffers from this problem. SSDs, pendrives, SD cards, Compact Flash... Apparently games for the Nintendo 3DS and PS Vita are already suffering from this, and people losing photos in faulty SDs is hardly news.

paranoidrobot 11mo ago

For years I've been collecting a slowly growing pile of old drives from old devices as I had replaced them. I finally decided to do something about them and got myself a USB to IDE/SATA adapter and spent a week or so duplicating them so I could check if there was anything worthwhile to keep, before destroyig and sending them to an e-waste recycler. Some of those drives had been sitting around since early 2000. All except two of the mechanical drives just fired up and worked fine. One won't power on at all. One powers up, but reading from some sectors just results in failures. But the SSDs are another story. All blank/empty for any that were more than a few years old. Even though I know some were pulled from working machines.

whoisthemachine 11mo ago

Yes, for the same reason we don't have any perpetual motion machines.

asdefghyk 11mo ago

I note , CHEMICAL reactions proceed faster with heat. So this why data retention is longer if device is in "...cold storage.." (This situation is also know with old photographic film , if stored in low temperatures it can last cira 100 years, but if stored at much higher room? temperatures , the film deterioration is much faster ) In SSD drives digital bits are stored as a electrical charge amount for each "cell". I suspect these cells have been decreased in size to provide much larger numerically increased SSD storage amounts. The decreased cell size means the charge decreases below needed amount faster and ssd becomes unreliable. MORE IMPORTANTLY - I also contend the SSD CHIP DESIGNERS would have/SHOULD HAVE been aware of this size effect and the decreased SSD reliability was not publicised OR specified for the product data sheets. Presently I'm looking for articales that prove my suspicions or assertions

asdefghyk 11mo ago

From the above linked articale "... Your SSD data isn't as permanent as you think Even the cheapest SSDs, say those with QLC NAND, can safely store data for about a year of being completely unpowered. More expensive TLC NAND can retain data for up to 3 years, while MLC and SLC NAND are good for 5 years and 10 years of unpowered storage, respectively. ..." RE "...QLC NAND, can safely store data for about a year of being completely unpowered...." QLC Nand only reliably stores data for only a year . This would be within the warranty period for some products. This information should be more clearly shown to product purchasers.

dusted 11mo ago

This is true, but it is generally true. Even for UV-EPROMs the retention time can be as low as a 25 years, if kept warm, even with the window sealed correctly. Magnetic drives are quite a lot better, around 50 years. CD-RWs are somewhat wider in their stability, I have ~20 year old discs that are becoming unreadable because the actual foil is delaminating from the plastic disc. Meanwhile I have ~40 year old DS-DD floppies that are still fully readable even though their medium is in physical contact with the read/write heads (although here, again, storage conditions and especially the different brands/batches seem to make a difference).