Flash media longevity testing – 6 years later

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88 points | by 1970-01-01 1 day ago

11 comments

  • rambambram 26 minutes ago
    I could google it, but I would rather ask HN: what are the best pens (or pen(cil)/paper-combination) for keeping written text as long as possible? I had some Stabilo pen which was very nice ergonomically, but the blue ink faded within a couple of years (laying on my window sil in the sun, but still).

    My guess is: regular graphite pencil on porous paper is best. Any ideas about further things I have to take into account?

    • lich_king 0 minutes ago
      I don't think there's a simple answer. For example, someone recommended black ink on white paper, but it really depends on the composition of that ink. Inorganic pigments last forever, but the ink used in black sharpies actually fades pretty quickly.

      Pencil definitely lasts if the paper is undisturbed. I have some paperwork that's 100+ years old and with legible pencil text. On the flip side, if the paper is handled a lot, it will gradually fade because graphite particles just sit on the surface and can flake off.

    • fhdkweig 7 minutes ago
      I vote for graphite on paper. Ink will run if the paper gets wet. Of all the damage that has occurred to my papers, water is the most common. I keep a copy of important phone numbers written inside my wallet in case I ever lose my phone. Between an unexpected rainstorm, to an unchecked pocket before putting pants in a washing machine, to a spilled drink, I have gotten my wallet wet several times. Every time I used ink, I had to rewrite the list, but now with graphite, it isn't a problem.
    • sandworm101 20 minutes ago
      Black ink on white paper, stored in a cool dark place, will last many decades. If may fade but will remain readable. Want centuries? Use skin parchment. Millenia? An engraving pen on glass. Going for longer? Take a grinder to a block of granite, but the real problem there is the lack of geologically-stable storage on this planet.
  • ralferoo 2 hours ago
    I like the fact he's not just verifying all of them each year. AFAICR, reading the flash causes the row to be rewritten with the values just read.

    I remember years ago working on the Wii, and there was a restriction on how often you could read the flash to avoid premature wearing. Not sure if that was just the specific type of storage, as googling suggests that NAND is subject to this and NOR isn't. I think pretty much all USB drives now use NOR flash, so maybe this isn't actually an issue any more.

    • wmf 1 hour ago
      reading the flash causes the row to be rewritten with the values just read

      DRAM works that way but flash doesn't. Read disturb is a different issue.

      pretty much all USB drives now use NOR flash

      Nope, NOR flash is much more expensive than NAND so NOR is only used for firmware and everything else is NAND.

      • cyberax 2 minutes ago
        But the firmware might have the logic to rewrite the block when it reads it in case it hasn't been written in a while.
    • zozbot234 1 hour ago
      > reading the flash causes the row to be rewritten

      This only happens very rarely, though more frequently as NAND flash goes QLC and beyond.

      Besides, other experiments have shown that data remanence is way more of an issue with drives that are almost completely worn out (way beyond their specified TBW) and about to croak. Even then you only get rare bitrot that can be checked for and compensated quite cheaply in most cases.

      If you take fresh media, write it just once or a few times at most, use substantial overprovisioning to keep the drive in its fast pseudo-SLC mode, and reread the media periodically, NAND can be a good enough storage system for most casual needs.

  • somat 1 hour ago
    On a related subject, physical media, like a song album. I started by wondering if there were ever any solid state distribution options (One Company tried SD cards) and then started digging into the underlying storage tech to see if I could find a write once long term stable process.

    First the elephant in the room. Why solid state? because the drives to read the media are often the weak link. When the drives are no longer being manufactured how hard is it to make one? reading solid state drives is a relatively low precision electrical process compared to the high precision mechanical process needed for most media.

    First on the chopping block was bulk storage. It tends to be delicate and hard to read and short lifespans. But if I limited myself to small storage there are some interesting options. fusible proms were promising but top out at a few megabytes. Mask roms? does anyone offer a mask rom service anymore?

    Put a mask rom into a sd card... no, sd cards are too physically small. For a song album we want something bigger to put album art on. A thing the size of the original gameboy cartridge with a usb interface and a mask rom?

    My conclusion, for that specific goal, indefinite future storage of a song album. Vinyl records. low tech enough that it is easy to make a player for them.

  • ComputerGuru 2 hours ago
    Slightly related: I have a tool that writes random (incompressible) data to a disk and lets you verify it back without storing a copy (by using a csprng seed), initially developed for benchmarking SSDs that used to cheat to get better performance numbers but that can also be used for this purpose or to overwrite (“shred”) a disk: https://github.com/mqudsi/hddrand
    • fhdkweig 1 hour ago
      I haven't used badblocks https://en.wikipedia.org/wiki/Badblocks in about 10 years, but I was annoyed that this exact feature wasn't available for testing accidental swapping of block locations. badblocks only writes the same data to each block and thus they are all indistinguishable.
  • deltoidmaximus 27 minutes ago
    Interesting related thread that includes SSD firmware engineer fairfeather discussing refresh mechanism implementation: https://news.ycombinator.com/item?id=46038099
  • digdugdirk 2 hours ago
    What is the best consumer friendly long-term storage medium? Are we still better off with high capacity dvd/Blu ray discs?
    • bityard 59 minutes ago
      Recordable blu-ray discs have a reported lifespan of hundreds of years if left untouched, but the high-capacity ones (128GB) are not especially cheap right now and I assume the writing process is slow. The drives themselves may not be easy to come by in future decades. But they are your best bet for "I want my data to outlive my grandchildren."

      For the rest of us, a USB spinning rust hard drive formatted as exFAT is going to be hard to beat. You'll be able to plug this into virtually any computer made in the next few decades (modulo a USB adapter or two) and just read it. They are cheap (even allowing for the rising cost of storage), fast, and most importantly, they are easy. The data is stored magnetically, so is not susceptible to degradation just from sitting like SSDs or flash drives are.

      Of course, you should not store any important data on only ONE drive. The 3-2-1 backup rule applies to archives as well: 3 copies, 2 different media, 1 off-site.

    • orthogonal_cube 1 hour ago
      Probably depends on what “consumer-friendly” entails, how it’s stored, and the quantity of data.

      If we’re talking the average tech-illiterate to literate-but-cost-and-space-constrained person, probably Blu-Ray. A burner+reader combo with a stack of dual-layer discs is probably cost-effective. High-capacity HDDs would probably be equally effective if you can guarantee that they’re stored away from accidents and mishandling, but if it requires a SATA-to-USB adapter with assembly then it might possibly be out of reach for some consumers, and any risk of damage from movement could rule it out entirely.

      If we’re talking tech-savvy consumers who don’t have the IT budget of a corporation, maybe LTO-5 or LTO-6 tapes could work. Tapes themselves are very affordable and have a good shelf lifespan. Used libraries can be had for under $600. The primary issues would be finding one with an interface that works with your existing equipment and software to support tape read and write.

    • 1970-01-01 2 hours ago
      I've been a big fan of M-Disc BD-R.
    • layer8 1 hour ago
      Honestly: multiple copies of encrypted cloud storage. (Encryption just for privacy.) You need decentralized backups anyway. Alternatively, two NAS systems with some RAID variation in different locations that back up each other can be more cost-effective for large capacities.
    • BoredPositron 1 hour ago
      What's long-term? I have some dvd-rs that push 20-25 years and despite the plastic getting brittle they still work. I also have some ide drives that still work without problems after 40 years. I would rather aim for 20 years and upgrade the storage device if I still need to retain the data.
      • vel0city 1 hour ago
        That's a thought I hadn't had. The plastic of the disk getting so brittle it shatters in the drive due to age. I wonder what's the embrittlement profile of polycarbonate stored in reasonable condition.
  • monster_truck 2 hours ago
    Rewriting the data each year hides the actual issue here. Have had plenty of "nice" flash drives rot to hell in 18+ months of dormancy
    • benterris 2 hours ago
      Does rewriting data help prevent bit rot? Does it mean powered drives can take advantage of it by periodically rewriting the same data over?
      • monster_truck 1 hour ago
        It depends on the type of flash being used and the controller managing it. That he did not even identify the chips should inform you of the extent that these results can be trusted.

        All I can say for sure is that you should not trust any flash for long term storage, thumb drive or otherwise. In serious enough, high usage, high heat enviornments where everything working without problems or delay is part of what they are paying us to be responsible for, it is standard practice to clone fresh images to nvmes every time, with multiple spares that can be swapped out in minutes when they inevitably fail anyways.

      • vel0city 1 hour ago
        It depends on how the flash modules are maintained and their quality, but yes having freshly written data will imply better data consistency on flash media.

        Flash media relies on recharging, which may or many not happen often enough.

    • angry_albatross 2 hours ago
      Did you miss that there are 10 different drives and so they have 10 different years of tests where they are testing a completely untouched drive?
      • monster_truck 1 hour ago
        I don't think you're reading the results properly.
        • thinkling 1 hour ago
          I think they are reading it correctly. Year 1, they touched one drive and left 9 untouched. Year 2, they read one additional drive and left 8 untouched. Etc.
          • Springtime 1 hour ago
            Yes, it's also confirmed on the OP's blog linked in the post.
          • monster_truck 1 hour ago
            Those drives aren't being read
  • nullorempty 2 hours ago
    What's the simplest way to rewrite the data without actually copying the data? Like in place rewrite - you write what you read.
    • fhdkweig 2 hours ago
      I've seen "dd if=/dev/removable of=/dev/removable" suggested. I don't know if it actually works or if the OS optimizes it to a no-op.
      • piyh 46 minutes ago
        the risk of catastrophic data loss from misuse of `dd` makes my hackles rise just looking at this.

        I will never forget when I mixed up `if` and `of` during a routine backup.

        `cat /dev/sda > /mnt/myDisk2` is so much safer, explicit, and in unix norms. It's also faster because you don't have to tune block size parameters.

        Plus you can also do `pv /dev/sda > /mnt/myDisk2` to get transfer speed details.

        Friends don't let friends use `dd` where `cat` can do the same job.

    • hpb42 56 minutes ago
      Wouldn't a ZFS Scrub get the job done?
  • jmakov 4 hours ago
    Powered all the time on or powered off?
    • alnwlsn 3 hours ago
      OP says powered off.
  • 01HNNWZ0MV43FF 2 hours ago
    That's good. I want to keep some institutional knowledge and photos in "cold storage" and cloud subscriptions with a credit card and password are completely inviable.

    I'll probably get a spinner and a flash drive and hope one of them survives the years.

    • rpcope1 1 hour ago
      Unless the data is huge, you're probably going to be better off with M-Disc Blurays or DVDs, as they're explicitly designed for what you're trying to do.
    • fhdkweig 1 hour ago
      If privacy is your primary problem with cloud storage, I would suggest veracrypt containers. And if you aren't storing too much data, I would also suggest DVD/BluRay optical media with DVDisaster and PAR2 archives. I keep a DVD spindle in a safe deposit box that gets updated each year.
  • jflshci 47 minutes ago
    [dead]