11 ms·

The Reliability of Optical Disks

142 points by gandalfff 5y ago

rascul 5y ago
It feels weird to me to call optical media disks instead of discs.
- chrisseaton 5y ago
  It's American English / British English isn't it?
  - rascul 5y ago
    Laser disc, compact disc, digital video disc, and blu-ray disc are (from what I understand) officially spelled with the c. I'm in the US and that is the typical way to spell it that I see, but I also see the k is generally used for hard disk and floppy disk. That said, there are a lot more instances of "disk" than "disc" used in the comments here so far.
    - theandrewbailey 5y ago
      The reasoning I've seen, is that disc is the recording media itself, whereas disk includes things like a sleeve, case, and/or IO heads.
  - Wowfunhappy 5y ago
    Nope! Apple—of all companies—has a support article on this: https://support.apple.com/en-us/HT201697 https://support.apple.com/en-us/HT201697
    - chrisseaton 5y ago
      > Nope! https://en.m.wikipedia.org/wiki/Spelling_of_disc https://en.m.wikipedia.org/wiki/Spelling_of_disc > the spelling disk is more popular in American English, while the spelling disc is more popular in British English
      - rascul 5y ago
        > In 1979, the Dutch company Philips, along with Sony, developed and trademarked the compact disc using the "c" spelling. The "c" spelling is now used consistently for optical media such as the compact disc and similar technologies.
- jonsen 5y ago
  "(The spelling disk and disc are used interchangeably except where trademarks preclude one usage, e.g. the Compact Disc logo. The choice of a particular form is frequently historical, as in IBM's usage of the disk form beginning in 1956 with the "IBM 350 disk storage unit").": https://en.m.wikipedia.org/wiki/Disk_storage https://en.m.wikipedia.org/wiki/Disk_storage
gjsman-1000 5y ago
In my movie collection, I replaced almost every DVD I could with Blu-Ray. Not just because the quality is better - it was, as the author mentioned, the massively improved scratch resistance. When you have kids, it becomes cheaper in the long run. Also, we’re a quality over quantity family. We don’t want thousands of movies on several subscriptions. Everything we’ve ever liked fits on two four-foot-wide shelves.
ghostly_s 5y ago
I'm a bit skeptical of these conclusions without more detail on the methodology. Does "100% success rate!" mean the author was able to mount the disks and read some files off them? Or did they actually have some method to verify check-sums of every file to identify bitrot?
- blueflow 5y ago
  It matches my experience. Even decades-old CD-ROMs only fail when they are scratched or physically damaged, which you can prevent by keeping them in appropriate cases and always put them back after use.
  - deleted 5y ago
    [deleted]
  - codazoda 5y ago
    My own experience is different. I had several brands of CD media that lasted less than 10 years. Many of them you could see the damage (cracks through the shiny layer). Some were dark blue, some a light blue. Almost all of them were bad. I had them stored in a light proof zipper pouch and stored at room temperature in a closet. Maybe something special happened to them over the years but very few worked. This would have been some of the first CD-R and CD-RW media available. I opened them more than 20 years ago so the media would have been 30 to 40 years old today. Anyway, I haven’t trusted optical since then.
    - xupybd 5y ago
      Some plastics can react with other plastics you have to be careful when storing long term in plastic bags for this reason. I'm not at all sure if this played a part in your CDs but it's possible.
    - dTal 5y ago
      CD-ROM != CD-R/RW
  - ghostly_s 5y ago
btrettel 5y ago
> What I didn’t realise at the time, was that all these CDs and DVDs would become a grand experiment of reliability and longevity. When I read data from these backup disks in 2021, I had a 100% success rate! My own experience is pretty good, but not 100%. I burned a lot of CDs from 2001 to 2006 or so. Most were discarded at some point, but in late 2019 I ripped all that I had (39 CDs) with (GNU) ddrescue. The vast majority (77%) had some small amount of read errors. I was able to recover 99.88% on the worst disk (a brand I'm not familiar with: "D"). That disk was about 15 years old. That's pretty good, but not 100%. This experience underlined to me the importance of having parity files in addition to the disks themselves. When I do a Blu-ray backup now (roughly once a year for the most important files), I also burn a DVD with par2 files. Back in the 00s I didn't verify checksums, but as a test I checked zip, gz, and png files on the oldest disk I had (Jan. 2001, 100% recovered). Those files have internal checksums to detect corruption. All those files passed. I should probably perform the same check on the other disks. Edit: I ran my script to check internal checksums on my disk image for my worst disk and 19 out of 635 files tested were corrupt, all png files. That is worse than the recovery percentage that ddrescue reports (97.01% valid vs. 99.88% recovered). That's roughly 0.2% lost per year.
KennyBlanken 5y ago
Aside from the author dismissing tape because "drives are expensive" and then concluding that the primary disadvantage to optical is "the discs are expensive" (wow, big surprise...) and then he doesn't bother to actually calculate the costs of either... ...and not describing how they tested for errors... ...and not having particularly rigorous testing methodology (the DVD was apparently left for three months before he got around to checking it)... ...no organization looks at a requirement like "archive these records for 50 years" and then commands its IT department to only store the data on media that will be expected to survive 50 years. What you do is store the data in such a way that your chance of losing data per year is within acceptable margins, on the most suitable storage method at the time, and migrated periodically when that system's chance of data loss falls below acceptable margins, appears to be getting too impractical to operate/maintain, or there are improvements in reliability or practicality. That can include factors like cost, availability of knowledgeable labor (ask the IRS how finding COBOL programmers is going), parts/service availability/cost, and so on. Other comments: > HDDs, especially NAS disks, have an “always on” assumption Even in the early 2000's, commercial NASes were offering systems that could power down portions of the array that were unused. There was significant interest in minimizing opex, and that's mostly power. Nowadays unraid and other solutions allow for the same. > And if you ever wanted to take disks offline and store them on a shelf, you don’t really know how long they’ll survive - unless you plug them in every now and then. "you don't know if that HDD is gonna work if it's sitting on a shelf" is irrelevant because your backups shouldn't be sitting on a shelf for any significant period of time, regardless of the media/mechanism. See discussion above: you should be rotating your media off-site periodically, bringing it back for tests. The biggest problem with HDDs is that SATA connectors are not rated for frequent use; their connect/disconnect rating is often in the range of "hundred or so." (This can be partially addressed by using a cable that stays plugged into the drive, and replacing the cable when it is past a certain number of cycles.) > if you ever wanted to take disks offline and store them on a shelf, you don’t really know how long they’ll survive - unless you plug them in every now and then. > And yet, the expectation is, that you will be able to read the disks without problem - even with zero maintenance. Indeed, that was the outcome of my ~15 year experiment! That's not the expectation, at all? CD-Rs used to have a lifetime measured in months before they start showing failures, especially if they had an adhesive label. I don't understand how the author possibly could be reading ten year old CD-Rs. That's basically impossible. DVD-Rs faired a bit better, and bluray disks even better. The issue with HDDs is the lubrication of the motor > any NAS will automatically check for errors, and notify if problems are found. No. No. No. NO. This is probably one of the biggest myths of RAID and NAS devices. Just because you have a RAID array doesn't mean it is configured to scrub its arrays; this often has to be enabled. Just because you have a RAID array scrubbing doesn't mean you're going to find out about it. Make sure your reporting works, and ideally report on success, not just failure, and have something else that reports on failure to receive Last but not least: Just because your RAID array controller (or software) finds a parity error or unreadable block doesn't mean it does what you expect, and most people expect "beep bop boop, parity/mirror inconsistency detected. Fixed, meatsack! Pat yourself on the back for being smart in using RAID." Reality: "beep bop boop, parity or mirror inconsistency detected, so go and verify your files or restore from backup, meatsack." RAID arrays cannot self-repair mirror or parity errors because there is no way to do so. The array controller has no idea whether it's the parity bit that is wrong, or the data. In a mirror, it has no idea which drive is correct - just that one of them is bad. RAID is not for data consistency. This is why ZFS is usually the top pick for data consistency: it knows the checksum of files and metadata, in addition to the on-disk redundancy via mirrored copies or parity. If it finds an error, it can play out both scenarios to see which results in files or metadata that match their checksum.
kevin_thibedeau 5y ago
This misses the most reliable optical media which is DVD M-disc.
- password4321 5y ago
  No longer manufactured, I believe; only available on eBay?
  - kevin_thibedeau 5y ago
    It is still made.
    - Skiiing 5y ago
      No. DVD M-disc are no longer manufactured, only blu-ray M-Disc is available. Which is a pity, because the DVD version was rated for longer longetivity.
bufferoverflow 5y ago
I have many degraded CDs and DVDs from 2000-2010. No drive would read them. Most from reputable brands. Most non-RW. All stored in dark places, indoors.
- superkuh 5y ago
  I have many degraded CDs from 1998-2010. In 2019 almost all of them would read, eventually, even as metal flakes came off the disks. I recovered most data from most. My CD-Rs were a mix of brands, nothing special or expensive. But my CD-drives are old too, from 2006(?) or so. I wonder if like with floppy disks and drives, modern CD drives are less capable than old ones because they're no longer a premium product?
  - btrettel 5y ago
    > I wonder if like with floppy disks and drives, modern CD drives are less capable than old ones because they're no longer a premium product? When I ripped CDs I had from the 00s in 2019, I used an external Blu-ray drive from probably 2018 or so. Seemed to work okay; see [0]. I didn't have access to anything older so I can't compare but I think both new and old drives are probably good. [0] https://news.ycombinator.com/item?id=30889474 https://news.ycombinator.com/item?id=30889474
    - robocat 5y ago
      Blu-ray discs use a red laser, and CD-ROMs use an infrared laser. The drives contain two laser diodes. Skip to 5:50 in https://www.youtube.com/watch?v=h9lbrr04XBQ https://www.youtube.com/watch?v=h9lbrr04XBQ
      - neuralRiot 5y ago
        Blu-ray uses blue laser (blue-ray!) DVD uses red and CD infrared. Devices compatibles with the 3 mediums have 3 lasers on their optical pickup.
        5y ago
gotaquestion 5y ago
I have 5-1/4" floppies the early 80's that still read fine. I wonder if 3.5" floppies from 1995 would still work. I have a feeling the media was made more robustly in the early 80's because the sensors weren't that precise, so bits were written with way more field than they needed. Maybe in the 90's when so many bits were crammed on to the 3.5" that they weren't written as strong? Perhaps the same is true of optical media. Are higher density optical disks from later in the era less robust than earlier tech. Like the way Hobart mixers from the early 1900's are built like tanks and can outlast ones built today to save money.
- TacticalCoder 5y ago
  During the first lockdown I dug out my old Commodore 128 and quite a few discs were still reading fine... But not all of them. I don't remember the ratio but I'd say about 2/3rd were still working.
causality0 5y ago
Finally, optical disks are more expensive than HDDs - at least in cost per GB. A 4TB NAS branded HDD costs ~AU$160, which is ~4c/GB. My last BluRay purchase was for 3 x 50 spindles of 25GB disks costing AU$330, which works out to be ~9c/GB. For anybody with deep knowledge of the industry, is the price of discs an accurate reflection of costs or is it inflated by secondary factors such as attempts to make the media more expensive to deter piracy or Sony's desire for high profit margins on data storage? I well remember Sony's shenanigans from the 2000s when they made great hardware and then only accepted MemoryStick instead of SD cards while charging much more for their flash format. I was so excited for BluRay and then prices just never came down enough to be practical.
- 29083011397778 5y ago
  I thought BluRay was subject to the blank media levy in Australia, but apparently not! [0] Note that not every country got off without though - just a few lines down, the article notes the levy is present on BluRay discs in Finland, among others. As an aside, I'm of the impression not enough people know about this levy. It feels to me like the kind of thing that fouls up the "nothing to hide" arguments regarding privacy; that is, a law few know about, but one that affects lots of people that wouldn't necessarily agree with being charged for something they may not be doing. While I'm sure some people still pirate and rip to BluRay, I'd assume they're just as likely used for things such as home movies, format shifting (which is legal in Canada [1]), or just plain backups (which I use for important files like a keepass database or 2FA codes). While this has drifted off-course slightly, it may at least have given you an answer regarding why BluRay discs didn't fall too far in price - at least if you're based in Finland. [0] https://en.wikipedia.org/wiki/Private_copying_levy#Australia https://en.wikipedia.org/wiki/Private_copying_levy#Australia [1] https://www.michaelgeist.ca/2012/11/c-11-impact/ https://www.michaelgeist.ca/2012/11/c-11-impact/
  - causality0 5y ago
    It's bizarre to me that lawmakers can get away with corruption that blatant.
spansoa 5y ago
Worth looking into Millennium Disc or M-DISC[0]. Apparently it's media that can last 1000 years. Thinking of buying two 50GB disks and putting some backup files on them when I have a few coins to drop. [0] https://en.wikipedia.org/wiki/M-DISC https://en.wikipedia.org/wiki/M-DISC
- oskarpearson 5y ago
  The article covers m-disc extensively, not sure why you’re linking Wikipedia here?
- hlieberman 5y ago
  The author explicitly notes that he is testing M-Discs; in fact, for heat, he only tests M-Discs.
- kevin_thibedeau 5y ago
  BD M-disc is the same as a normal BD-R. The DVD M-disc is the only one worth considering for long time archival storage.
  - Wowfunhappy 5y ago
    What makes you say that? The article appeared to find a significant difference in the reliability of standard BD-R's and M-Disc BD-R's.
    - dsego 5y ago
      There are two types of BD-Rs, high to low & low to high. One is bad for long term and one is good (something something inorganic), but I forget which is which. From my research online bluray m-disc is just the better one but m-disc branded, apparently not the same stuff as the original m-disc DVD.
hlieberman 5y ago
If I am looking at a ~100 years timescale for preservation of documents, there are exactly two choices that I would consider. At the hundreds of years timescale, exactly one. Those are, in order: 1. Microfilm/microfiche 2. Ink on 100% cotton paper, or ink on vellum The properties of microfilm have been well studied. It requires no technology other than a magnifying glass to read, has a well over 500 year lifespan in studies, and has exemplars that have survived more than 150 years. Ink on paper, on the other hand, we have exemplars that are almost 1000 year old, with ink on vellum more than 2000 years old. It requires no tools whatsoever to read, and we have been working and understanding how it is best preserved for hundreds of years.
- simonebrunozzi 5y ago
  How would you "print" your backup on a microfilm?
  - formerly_proven 5y ago
    Lasers, just like normal film prints.
  - tablespoon 5y ago
    > How would you "print" your backup on a microfilm? There are services that can do that for you. You send them document images, they send microfilm back. I've never actually done it, but I've considered it, an I had this random service in my bookmarks: https://overnight-scanning.eu/microfilming-service/ https://overnight-scanning.eu/microfilming-service/
- TacticalCoder 5y ago
  I've got a printed book from 1575 here. Some pages at the beginning are in a bad shape but otherwise everything is still perfectly readable. I don't know which type of paper/ink it's using though. It's some book about plants: apparently one of the most printed book (after the bible) back in its days.
- FredPret 5y ago
  How about building a pyramid with carvings on the inside? I bet that would last. You could even encode data by the presence or absence of a pyramid
uniqueuid 5y ago
One option that hasn't been mentioned is tape archives. It's not for everyone, but tapes (LTO) do have a lot of technology and infrastructure behind them that is built for longevity. In particular, you can do cost-efficient archives to multiple tapes and store them in safe locations. If (and that's a big if) the base cost of the drive is tolerable. There was recently a wonderful post and discussion on LTO for "normal" nerds [1]. [1] https://news.ycombinator.com/item?id=30099540 https://news.ycombinator.com/item?id=30099540
- btrettel 5y ago
  One thing that keeps me from trying tapes is that they are still magnetic. If there's some sort of local electromagnetic event then I'd prefer to have a backup that can handle that. I keep some backup hard drives in metal boxes, which is probably enough (Faraday cage). However, optical disks can almost certainly survive a major electromagnetic event without special precautions.
  - uniqueuid 5y ago
    Interesting. Is a magnetic event more plausible for you than other types of decay? I'd expect physical damage from something like a flooding to be much more likely than some sort of magnetic interference. But that probably depends on the location you live in!
    - wtetzner 5y ago
      I think the idea is just to have different kinds of backups that have different failure modes, to make losing everything at once less likely.
    - btrettel 5y ago
      I don't know how likely some sort of electromagnetic event is. I just figure that if I'm going to diversify my backup strategies then something dissimilar/uncorrelated would probably be a better choice. My data is on magnetic hard drives, SSDs, and optical disks, each of which has different risk profiles. As wtetzner said, it's unlikely that a single event could cause all of these to fail. An EMP attack might take out my magnetic hard drives and SSDs but leave the optical disks unaffected. I've also had a hard drive fail due to impact damage that likely would not affect a SSD. Flooding is not something I've thought about before, but since my backups are located in different geographical areas, I should be covered there. Etc.
WalterBright 5y ago
I buy multi-terabyte drives when they go on sale (which is often) and copy everything forward once a year or so. I don't trust old media of any sort.
- digisign 5y ago
  Interesting because hard disks are not a particularly reliable form of backup. As long as you have enough copies.
  - WalterBright 5y ago
    I know, I've had many fail on me over the years. Quantity, though, has a quality all its own!
    - lostmsu 5y ago
      Same here. I just have a mirrored Storage Space for critical data with ReFS and checksums (though Microsoft did not make that one easy to understand so I am unsure if the data is safe that way). UPD. just searched, and found, that I needed to enable periodic scrubbing in Task Scheduler: Microsoft -> Windows -> Data Integrity Scan section. I already had data integrity streams enabled (another thing you have to do manually after creating the volume).
digisign 5y ago
Would concur. I went thru all my old optical discs in ~2020 and moved all backups to 100GB Bluray. Went from dozens of discs to about three. Then I destroyed most of the old ones. (Didn't bother with some... does anyone need a copy of Netware 3.x or 4.x anymore? Even though it was so cool at the time.) All my CDs/DVDs burned from about '97 onwards were in perfect condition. I think one deteriorated, stuff I didn't care about given to me. I never bought super-cheap ones, maybe that helped. I did save a few "mix tape" discs from the era for nostalgia purposes. Imagine 15 of the best songs from different artists on ONE disc! It was a big kick to make your own CDs at the time... would blow people's minds, when you showed them. :-D
- jbverschoor 5y ago
  About a month ago I went trough all my CD/DVDs. Factory disks were all good. But burned disks, especially the later cheaper ones mostly were either in bad condition, or not even recognized as media.
  - digisign 5y ago
    Brand? Treatment? I just grabbed one from my DJ days: TDK dated 1997-01-01: https://imgur.com/a/I7fokrx https://imgur.com/a/I7fokrx Listening to it now. We are… family ♪♫♪
    - jbverschoor 5y ago
      After '00, the market was flooded with cheap discs.. Most of the bad ones were those.
      - digisign 5y ago
        I see. My DVDs were also fine, but I did stick to known brands, if memory holds.
  - amelius 5y ago
    There are specialized companies who claim to be able to recover data from just about anything. Probably expensive, though.
nayuki 5y ago
Great article discussing the benefits of optical discs and the author's own experience of using them! I burned hundreds of discs a decade ago and read them all back perfectly, to my surprise. I strongly agree with the write-once behavior for photos and downloads. HDDs worry me in the long term because even if the platter holding the data is fine, the R/W head, mechanics, and electronics could fail, not to mention that a head crash could wipe out good data. I'm extremely disappointed that the capacity of optical disc formats are essentially frozen, topping out at 100 or 128 GB for BD XL. They're definitely not keeping up with the continual increase in storage density and decreasing cost of hard disks and flash memory. Why are new formats not forthcoming? Where's my 300 GB Archival Disc? Where's my 1 TB holographic disc? Where's Microsoft's glass optical disc that's stable for millions of years? I want to keep on burning optical discs and putting them in cold storage, but this gradually obsolete technology is not making a convincing case for me today. Previously: https://news.ycombinator.com/item?id=26038893 https://news.ycombinator.com/item?id=26038893 , https://news.ycombinator.com/item?id=29221418 https://news.ycombinator.com/item?id=29221418
- tinus_hn 5y ago
  How many people are buying these 128GB discs? Probably not a whole lot and that is the reason why nobody’s going to make the investment to create bigger discs. If you want huge local offline storage, the solution is tapes.
  - smackeyacky 5y ago
    Even lowly LTO2 is 400gb. Plus the reliability of long term storage of tape is much better researched.
  - em3rgent0rdr 5y ago
    But it is already known that magnetic tape is much less reliable in long term storage. The author is looking for long-term reliability, not just huge local offline storage.
    - tinus_hn 5y ago
em3rgent0rdr 5y ago
Could do RAID 4/5/6 with Optical Disks too for additional paranoia. Ideally there should be some machine to go through old backups and upon first detection of an error, then it could regenerate the array from the remaining discs of that array.
- tenebrisalietum 5y ago
  Use PAR2 files, like Usenet does.
- NavinF 5y ago
  That’s the biggest problem with optical disks. With no automation, it’s totally impractical for one person to maintain a full backup of everything they care about. 100TB is like 2000 discs plus parity.
  - em3rgent0rdr 5y ago
    Yeah. Though it is not difficult to build such a machine and similar machines have been around, such as CD Jukebox players and multi-disc burners.
gandalfff 5y ago
My biggest concern with Optical Disks is obsolescence and convenience. I bought some DVD media to do some backups but so far I have only backed up a portion of my photos. Right now my files are being stored on my MacBook's internal SSD, Backblaze, Google Drive, and a Time Machine backup on an SD card that stays in the SD slot. I do full backups to external hard drives every so often. I'm too lazy for any backup method that requires an involved process like optical media. And I also find myself asking if it's even worth it. I don't think my files are that valuable, to be honest. I would be sad to lose them, but it might also be freeing in a minimalist sort of way.
tambourine_man 5y ago
I had a different experience. A good fraction of the CD/DVDs burned 10-20 years ago won’t read. At least not trivially.
yeetsfromhellL2 5y ago
RO media is great, especially when you're concerned about data integrity and may not completely trust a machine writing or verifying the media. Consider you're downloading sensitive data from the internet, or just writing sensitive data on an internet connected machine (maybe it's OS installation media, or important legal or financial docs, or you're a wall street or NSA whistleblower, or it's a Bitcoin key backup), and you're worried your machine may be compromised on account of it being connected to the internet; you may not want to stake the quality of the rest of your life on your computer not lying to you about file integrity. What do you do? Write it to RO media and take it to different computers to verify the checksum/signature. You don't need to worry about other machines, which are also potentially compromised, corrupting the data. You also don't have to worry about something like BadUSB, where the USB device's microprocessor firmware infects the host machine (or vice versa) before the data payload is even read. This means you can put the disk in your secure airgapped machine at home, even after it's been in the machine at the local library. You create a concensus of file integrity after reading and verifying the data across a range of machines. Obviously there are other attack vectors, but with the cost of these sorts of attacks (badUSB, or simply getting rooted) going down, the accessibility going up, and the potential rewards becoming more valuable and widespread, it's an attack vector to consider for important data.
SnowHill9902 5y ago
What do you people need to store so much for so long? Backups are rolled-over ever few days. Personal photos and videos?
- the_af 5y ago
  Personal photos and videos indeed, I would guess. The one piece of data you can never get back or buy back if your only copy breaks down. Also, a kind of data that takes a lot of space, compared with, say, text documents.
fghorow 5y ago
When I was in grad school back in the '80s, 9 track magtapes were the standard for lots of things: backups and long term storage being some of them. (I still have one or two tapes in a box somewhere.) About 10-15 years ago, it dawned on me that I hadn't seen a working tape drive in quite a while. Any tapes, even if the media were intact (highly doubtful, and the point of the parent article) would not be readable. Much the same comment for boxes of punch cards. (My late colleague used to tear off pieces of the cards and use them for "filters" in his roll-your-own cigarettes.) I guess my point is, even if the media are reliable (holes in cardboard? pretty foolproof from an ink-on-vellum viewpoint) the entire surrounding ecosystem needs to survive for archival purposes.
ris 5y ago
Not very actively maintained these days but https://en.wikipedia.org/wiki/Dvdisaster https://en.wikipedia.org/wiki/Dvdisaster stores error correction codes in the remaining space on an optical disk, without affecting its readability by unaware systems.
lostgame 5y ago
Extremely lucky about this ‘100% success rate’. After dealing with several valuable SEGA Saturn games that succumbed to bit rot, and are therefore worth practically nothing - (nor are they playable, obviously) - I backed up whatever optical disks I had left and have never used optical media since. I certainly never will again. I just can’t trust it anymore as an investment. I’ve got vinyl from the 50’s/60’s that still play great but after losing those SEGA games I just see those little plastic disks as ticking time bombs.
eezurr 5y ago
Here's an older article on Disc Rot, for some counter points https://www.vice.com/en/article/mg9pdv/the-hidden-phenomenon-that-could-ruin-your-old-discs https://www.vice.com/en/article/mg9pdv/the-hidden-phenomenon... [1] https://www.howtogeek.com/682807/the-cds-you-burned-are-going-bad-heres-what-you-need-to-do/ https://www.howtogeek.com/682807/the-cds-you-burned-are-goin... [2] [1] https://news.ycombinator.com/item?id=21668184 https://news.ycombinator.com/item?id=21668184 [2] https://news.ycombinator.com/item?id=23979241 https://news.ycombinator.com/item?id=23979241
msie 5y ago
5.5 TB Optical Disc: https://www.bhphotovideo.com/c/product/1549173-REG/sony_odc_5500r_us_5_5tb_optical_disc_archive.html https://www.bhphotovideo.com/c/product/1549173-REG/sony_odc_... Drive: https://www.bhphotovideo.com/c/product/1549175-REG/sony_odsd380u_optical_disc_archive_gen3.html https://www.bhphotovideo.com/c/product/1549175-REG/sony_odsd... (only about $9k)
donatj 5y ago
I personally was going through a large binder of old backups this week that's been in my parents basement away from sun for 15 years. Many CDs and later DVDs. The DVDs were all seemingly fine but a sizable portion, maybe 20%, of the CDs are flaking along the outside. I was honestly kind of surprised.
namibj 5y ago
9ct/GB for plain BD-R is a rip-off. They cost 0.08 USD a piece (if you reach MOQ on Alibaba), plus about the same as patent license fees. So 16ct/25GB, not 9ct/GB. Taking storage overhead (cases of some sort; spindles aren't well-suited to store BD long-tem) into account, the Chinese 20ct/50GB (plus patent; iirc sub-linear scaling with capacity?) option of a DL BD-R may easily be cheaper over all.
- R0b0t1 5y ago
  My costing put it as positive compared to disk even without massive discounts, but physical volume is a problem, and cheaply constructed disks are volatile. There's an open space for cheap tape drives.
codezero 5y ago
I wish I did more rigorous work on this but I managed a large Rewritable DVD backup for a satellite instrument with over 3000 DVDs stored in a filing cabinet for almost ten years. When I joined about three years in I added checksums to the backups and infrequently sampled and reburned older discs and found zero corruption after almost a decade stored in those conditions. Given there was a mix of R and RW burned discs I was actually pretty surprised there was no corruption because I had it ingrained in my mind these things shouldn’t last so long.

142 points by gandalfff 5y ago

rascul 5y ago

It feels weird to me to call optical media disks instead of discs.

chrisseaton 5y ago
It's American English / British English isn't it?
- rascul 5y ago
  Laser disc, compact disc, digital video disc, and blu-ray disc are (from what I understand) officially spelled with the c. I'm in the US and that is the typical way to spell it that I see, but I also see the k is generally used for hard disk and floppy disk. That said, there are a lot more instances of "disk" than "disc" used in the comments here so far.
  - theandrewbailey 5y ago
    The reasoning I've seen, is that disc is the recording media itself, whereas disk includes things like a sleeve, case, and/or IO heads.
- Wowfunhappy 5y ago
  Nope! Apple—of all companies—has a support article on this: https://support.apple.com/en-us/HT201697 https://support.apple.com/en-us/HT201697
  - chrisseaton 5y ago
    > Nope! https://en.m.wikipedia.org/wiki/Spelling_of_disc https://en.m.wikipedia.org/wiki/Spelling_of_disc > the spelling disk is more popular in American English, while the spelling disc is more popular in British English
    - rascul 5y ago
      > In 1979, the Dutch company Philips, along with Sony, developed and trademarked the compact disc using the "c" spelling. The "c" spelling is now used consistently for optical media such as the compact disc and similar technologies.
jonsen 5y ago
"(The spelling disk and disc are used interchangeably except where trademarks preclude one usage, e.g. the Compact Disc logo. The choice of a particular form is frequently historical, as in IBM's usage of the disk form beginning in 1956 with the "IBM 350 disk storage unit").": https://en.m.wikipedia.org/wiki/Disk_storage https://en.m.wikipedia.org/wiki/Disk_storage

gjsman-1000 5y ago

In my movie collection, I replaced almost every DVD I could with Blu-Ray. Not just because the quality is better - it was, as the author mentioned, the massively improved scratch resistance. When you have kids, it becomes cheaper in the long run. Also, we’re a quality over quantity family. We don’t want thousands of movies on several subscriptions. Everything we’ve ever liked fits on two four-foot-wide shelves.

ghostly_s 5y ago

I'm a bit skeptical of these conclusions without more detail on the methodology. Does "100% success rate!" mean the author was able to mount the disks and read some files off them? Or did they actually have some method to verify check-sums of every file to identify bitrot?

blueflow 5y ago
It matches my experience. Even decades-old CD-ROMs only fail when they are scratched or physically damaged, which you can prevent by keeping them in appropriate cases and always put them back after use.
- deleted 5y ago
  [deleted]
- codazoda 5y ago
  My own experience is different. I had several brands of CD media that lasted less than 10 years. Many of them you could see the damage (cracks through the shiny layer). Some were dark blue, some a light blue. Almost all of them were bad. I had them stored in a light proof zipper pouch and stored at room temperature in a closet. Maybe something special happened to them over the years but very few worked. This would have been some of the first CD-R and CD-RW media available. I opened them more than 20 years ago so the media would have been 30 to 40 years old today. Anyway, I haven’t trusted optical since then.
  - xupybd 5y ago
    Some plastics can react with other plastics you have to be careful when storing long term in plastic bags for this reason. I'm not at all sure if this played a part in your CDs but it's possible.
  - dTal 5y ago
    CD-ROM != CD-R/RW
- ghostly_s 5y ago

btrettel 5y ago

> What I didn’t realise at the time, was that all these CDs and DVDs would become a grand experiment of reliability and longevity. When I read data from these backup disks in 2021, I had a 100% success rate! My own experience is pretty good, but not 100%. I burned a lot of CDs from 2001 to 2006 or so. Most were discarded at some point, but in late 2019 I ripped all that I had (39 CDs) with (GNU) ddrescue. The vast majority (77%) had some small amount of read errors. I was able to recover 99.88% on the worst disk (a brand I'm not familiar with: "D"). That disk was about 15 years old. That's pretty good, but not 100%. This experience underlined to me the importance of having parity files in addition to the disks themselves. When I do a Blu-ray backup now (roughly once a year for the most important files), I also burn a DVD with par2 files. Back in the 00s I didn't verify checksums, but as a test I checked zip, gz, and png files on the oldest disk I had (Jan. 2001, 100% recovered). Those files have internal checksums to detect corruption. All those files passed. I should probably perform the same check on the other disks. Edit: I ran my script to check internal checksums on my disk image for my worst disk and 19 out of 635 files tested were corrupt, all png files. That is worse than the recovery percentage that ddrescue reports (97.01% valid vs. 99.88% recovered). That's roughly 0.2% lost per year.

KennyBlanken 5y ago

Aside from the author dismissing tape because "drives are expensive" and then concluding that the primary disadvantage to optical is "the discs are expensive" (wow, big surprise...) and then he doesn't bother to actually calculate the costs of either... ...and not describing how they tested for errors... ...and not having particularly rigorous testing methodology (the DVD was apparently left for three months before he got around to checking it)... ...no organization looks at a requirement like "archive these records for 50 years" and then commands its IT department to only store the data on media that will be expected to survive 50 years. What you do is store the data in such a way that your chance of losing data per year is within acceptable margins, on the most suitable storage method at the time, and migrated periodically when that system's chance of data loss falls below acceptable margins, appears to be getting too impractical to operate/maintain, or there are improvements in reliability or practicality. That can include factors like cost, availability of knowledgeable labor (ask the IRS how finding COBOL programmers is going), parts/service availability/cost, and so on. Other comments: > HDDs, especially NAS disks, have an “always on” assumption Even in the early 2000's, commercial NASes were offering systems that could power down portions of the array that were unused. There was significant interest in minimizing opex, and that's mostly power. Nowadays unraid and other solutions allow for the same. > And if you ever wanted to take disks offline and store them on a shelf, you don’t really know how long they’ll survive - unless you plug them in every now and then. "you don't know if that HDD is gonna work if it's sitting on a shelf" is irrelevant because your backups shouldn't be sitting on a shelf for any significant period of time, regardless of the media/mechanism. See discussion above: you should be rotating your media off-site periodically, bringing it back for tests. The biggest problem with HDDs is that SATA connectors are not rated for frequent use; their connect/disconnect rating is often in the range of "hundred or so." (This can be partially addressed by using a cable that stays plugged into the drive, and replacing the cable when it is past a certain number of cycles.) > if you ever wanted to take disks offline and store them on a shelf, you don’t really know how long they’ll survive - unless you plug them in every now and then. > And yet, the expectation is, that you will be able to read the disks without problem - even with zero maintenance. Indeed, that was the outcome of my ~15 year experiment! That's not the expectation, at all? CD-Rs used to have a lifetime measured in months before they start showing failures, especially if they had an adhesive label. I don't understand how the author possibly could be reading ten year old CD-Rs. That's basically impossible. DVD-Rs faired a bit better, and bluray disks even better. The issue with HDDs is the lubrication of the motor > any NAS will automatically check for errors, and notify if problems are found. No. No. No. NO. This is probably one of the biggest myths of RAID and NAS devices. Just because you have a RAID array doesn't mean it is configured to scrub its arrays; this often has to be enabled. Just because you have a RAID array scrubbing doesn't mean you're going to find out about it. Make sure your reporting works, and ideally report on success, not just failure, and have something else that reports on failure to receive Last but not least: Just because your RAID array controller (or software) finds a parity error or unreadable block doesn't mean it does what you expect, and most people expect "beep bop boop, parity/mirror inconsistency detected. Fixed, meatsack! Pat yourself on the back for being smart in using RAID." Reality: "beep bop boop, parity or mirror inconsistency detected, so go and verify your files or restore from backup, meatsack." RAID arrays cannot self-repair mirror or parity errors because there is no way to do so. The array controller has no idea whether it's the parity bit that is wrong, or the data. In a mirror, it has no idea which drive is correct - just that one of them is bad. RAID is not for data consistency. This is why ZFS is usually the top pick for data consistency: it knows the checksum of files and metadata, in addition to the on-disk redundancy via mirrored copies or parity. If it finds an error, it can play out both scenarios to see which results in files or metadata that match their checksum.

kevin_thibedeau 5y ago

This misses the most reliable optical media which is DVD M-disc.

password4321 5y ago
No longer manufactured, I believe; only available on eBay?
- kevin_thibedeau 5y ago
  It is still made.
  - Skiiing 5y ago
    No. DVD M-disc are no longer manufactured, only blu-ray M-Disc is available. Which is a pity, because the DVD version was rated for longer longetivity.

bufferoverflow 5y ago

I have many degraded CDs and DVDs from 2000-2010. No drive would read them. Most from reputable brands. Most non-RW. All stored in dark places, indoors.

superkuh 5y ago
I have many degraded CDs from 1998-2010. In 2019 almost all of them would read, eventually, even as metal flakes came off the disks. I recovered most data from most. My CD-Rs were a mix of brands, nothing special or expensive. But my CD-drives are old too, from 2006(?) or so. I wonder if like with floppy disks and drives, modern CD drives are less capable than old ones because they're no longer a premium product?
- btrettel 5y ago
  > I wonder if like with floppy disks and drives, modern CD drives are less capable than old ones because they're no longer a premium product? When I ripped CDs I had from the 00s in 2019, I used an external Blu-ray drive from probably 2018 or so. Seemed to work okay; see [0]. I didn't have access to anything older so I can't compare but I think both new and old drives are probably good. [0] https://news.ycombinator.com/item?id=30889474 https://news.ycombinator.com/item?id=30889474
  - robocat 5y ago
    Blu-ray discs use a red laser, and CD-ROMs use an infrared laser. The drives contain two laser diodes. Skip to 5:50 in https://www.youtube.com/watch?v=h9lbrr04XBQ https://www.youtube.com/watch?v=h9lbrr04XBQ
    - neuralRiot 5y ago
      Blu-ray uses blue laser (blue-ray!) DVD uses red and CD infrared. Devices compatibles with the 3 mediums have 3 lasers on their optical pickup.
      - 5y ago

gotaquestion 5y ago

I have 5-1/4" floppies the early 80's that still read fine. I wonder if 3.5" floppies from 1995 would still work. I have a feeling the media was made more robustly in the early 80's because the sensors weren't that precise, so bits were written with way more field than they needed. Maybe in the 90's when so many bits were crammed on to the 3.5" that they weren't written as strong? Perhaps the same is true of optical media. Are higher density optical disks from later in the era less robust than earlier tech. Like the way Hobart mixers from the early 1900's are built like tanks and can outlast ones built today to save money.

TacticalCoder 5y ago
During the first lockdown I dug out my old Commodore 128 and quite a few discs were still reading fine... But not all of them. I don't remember the ratio but I'd say about 2/3rd were still working.

causality0 5y ago

Finally, optical disks are more expensive than HDDs - at least in cost per GB. A 4TB NAS branded HDD costs ~AU$160, which is ~4c/GB. My last BluRay purchase was for 3 x 50 spindles of 25GB disks costing AU$330, which works out to be ~9c/GB. For anybody with deep knowledge of the industry, is the price of discs an accurate reflection of costs or is it inflated by secondary factors such as attempts to make the media more expensive to deter piracy or Sony's desire for high profit margins on data storage? I well remember Sony's shenanigans from the 2000s when they made great hardware and then only accepted MemoryStick instead of SD cards while charging much more for their flash format. I was so excited for BluRay and then prices just never came down enough to be practical.

29083011397778 5y ago
I thought BluRay was subject to the blank media levy in Australia, but apparently not! [0] Note that not every country got off without though - just a few lines down, the article notes the levy is present on BluRay discs in Finland, among others. As an aside, I'm of the impression not enough people know about this levy. It feels to me like the kind of thing that fouls up the "nothing to hide" arguments regarding privacy; that is, a law few know about, but one that affects lots of people that wouldn't necessarily agree with being charged for something they may not be doing. While I'm sure some people still pirate and rip to BluRay, I'd assume they're just as likely used for things such as home movies, format shifting (which is legal in Canada [1]), or just plain backups (which I use for important files like a keepass database or 2FA codes). While this has drifted off-course slightly, it may at least have given you an answer regarding why BluRay discs didn't fall too far in price - at least if you're based in Finland. [0] https://en.wikipedia.org/wiki/Private_copying_levy#Australia https://en.wikipedia.org/wiki/Private_copying_levy#Australia [1] https://www.michaelgeist.ca/2012/11/c-11-impact/ https://www.michaelgeist.ca/2012/11/c-11-impact/
- causality0 5y ago
  It's bizarre to me that lawmakers can get away with corruption that blatant.

spansoa 5y ago

Worth looking into Millennium Disc or M-DISC[0]. Apparently it's media that can last 1000 years. Thinking of buying two 50GB disks and putting some backup files on them when I have a few coins to drop. [0] https://en.wikipedia.org/wiki/M-DISC https://en.wikipedia.org/wiki/M-DISC

oskarpearson 5y ago
The article covers m-disc extensively, not sure why you’re linking Wikipedia here?
hlieberman 5y ago
The author explicitly notes that he is testing M-Discs; in fact, for heat, he only tests M-Discs.
kevin_thibedeau 5y ago
BD M-disc is the same as a normal BD-R. The DVD M-disc is the only one worth considering for long time archival storage.
- Wowfunhappy 5y ago
  What makes you say that? The article appeared to find a significant difference in the reliability of standard BD-R's and M-Disc BD-R's.
  - dsego 5y ago
    There are two types of BD-Rs, high to low & low to high. One is bad for long term and one is good (something something inorganic), but I forget which is which. From my research online bluray m-disc is just the better one but m-disc branded, apparently not the same stuff as the original m-disc DVD.

hlieberman 5y ago

If I am looking at a ~100 years timescale for preservation of documents, there are exactly two choices that I would consider. At the hundreds of years timescale, exactly one. Those are, in order: 1. Microfilm/microfiche 2. Ink on 100% cotton paper, or ink on vellum The properties of microfilm have been well studied. It requires no technology other than a magnifying glass to read, has a well over 500 year lifespan in studies, and has exemplars that have survived more than 150 years. Ink on paper, on the other hand, we have exemplars that are almost 1000 year old, with ink on vellum more than 2000 years old. It requires no tools whatsoever to read, and we have been working and understanding how it is best preserved for hundreds of years.

simonebrunozzi 5y ago
How would you "print" your backup on a microfilm?
- formerly_proven 5y ago
  Lasers, just like normal film prints.
- tablespoon 5y ago
  > How would you "print" your backup on a microfilm? There are services that can do that for you. You send them document images, they send microfilm back. I've never actually done it, but I've considered it, an I had this random service in my bookmarks: https://overnight-scanning.eu/microfilming-service/ https://overnight-scanning.eu/microfilming-service/
TacticalCoder 5y ago
I've got a printed book from 1575 here. Some pages at the beginning are in a bad shape but otherwise everything is still perfectly readable. I don't know which type of paper/ink it's using though. It's some book about plants: apparently one of the most printed book (after the bible) back in its days.
FredPret 5y ago
How about building a pyramid with carvings on the inside? I bet that would last. You could even encode data by the presence or absence of a pyramid

uniqueuid 5y ago

One option that hasn't been mentioned is tape archives. It's not for everyone, but tapes (LTO) do have a lot of technology and infrastructure behind them that is built for longevity. In particular, you can do cost-efficient archives to multiple tapes and store them in safe locations. If (and that's a big if) the base cost of the drive is tolerable. There was recently a wonderful post and discussion on LTO for "normal" nerds [1]. [1] https://news.ycombinator.com/item?id=30099540 https://news.ycombinator.com/item?id=30099540

btrettel 5y ago
One thing that keeps me from trying tapes is that they are still magnetic. If there's some sort of local electromagnetic event then I'd prefer to have a backup that can handle that. I keep some backup hard drives in metal boxes, which is probably enough (Faraday cage). However, optical disks can almost certainly survive a major electromagnetic event without special precautions.
- uniqueuid 5y ago
  Interesting. Is a magnetic event more plausible for you than other types of decay? I'd expect physical damage from something like a flooding to be much more likely than some sort of magnetic interference. But that probably depends on the location you live in!
  - wtetzner 5y ago
    I think the idea is just to have different kinds of backups that have different failure modes, to make losing everything at once less likely.
  - btrettel 5y ago
    I don't know how likely some sort of electromagnetic event is. I just figure that if I'm going to diversify my backup strategies then something dissimilar/uncorrelated would probably be a better choice. My data is on magnetic hard drives, SSDs, and optical disks, each of which has different risk profiles. As wtetzner said, it's unlikely that a single event could cause all of these to fail. An EMP attack might take out my magnetic hard drives and SSDs but leave the optical disks unaffected. I've also had a hard drive fail due to impact damage that likely would not affect a SSD. Flooding is not something I've thought about before, but since my backups are located in different geographical areas, I should be covered there. Etc.

WalterBright 5y ago

I buy multi-terabyte drives when they go on sale (which is often) and copy everything forward once a year or so. I don't trust old media of any sort.

digisign 5y ago
Interesting because hard disks are not a particularly reliable form of backup. As long as you have enough copies.
- WalterBright 5y ago
  I know, I've had many fail on me over the years. Quantity, though, has a quality all its own!
  - lostmsu 5y ago
    Same here. I just have a mirrored Storage Space for critical data with ReFS and checksums (though Microsoft did not make that one easy to understand so I am unsure if the data is safe that way). UPD. just searched, and found, that I needed to enable periodic scrubbing in Task Scheduler: Microsoft -> Windows -> Data Integrity Scan section. I already had data integrity streams enabled (another thing you have to do manually after creating the volume).

digisign 5y ago

Would concur. I went thru all my old optical discs in ~2020 and moved all backups to 100GB Bluray. Went from dozens of discs to about three. Then I destroyed most of the old ones. (Didn't bother with some... does anyone need a copy of Netware 3.x or 4.x anymore? Even though it was so cool at the time.) All my CDs/DVDs burned from about '97 onwards were in perfect condition. I think one deteriorated, stuff I didn't care about given to me. I never bought super-cheap ones, maybe that helped. I did save a few "mix tape" discs from the era for nostalgia purposes. Imagine 15 of the best songs from different artists on ONE disc! It was a big kick to make your own CDs at the time... would blow people's minds, when you showed them. :-D

jbverschoor 5y ago
About a month ago I went trough all my CD/DVDs. Factory disks were all good. But burned disks, especially the later cheaper ones mostly were either in bad condition, or not even recognized as media.
- digisign 5y ago
  Brand? Treatment? I just grabbed one from my DJ days: TDK dated 1997-01-01: https://imgur.com/a/I7fokrx https://imgur.com/a/I7fokrx Listening to it now. We are… family ♪♫♪
  - jbverschoor 5y ago
    After '00, the market was flooded with cheap discs.. Most of the bad ones were those.
    - digisign 5y ago
      I see. My DVDs were also fine, but I did stick to known brands, if memory holds.
- amelius 5y ago
  There are specialized companies who claim to be able to recover data from just about anything. Probably expensive, though.

nayuki 5y ago

Great article discussing the benefits of optical discs and the author's own experience of using them! I burned hundreds of discs a decade ago and read them all back perfectly, to my surprise. I strongly agree with the write-once behavior for photos and downloads. HDDs worry me in the long term because even if the platter holding the data is fine, the R/W head, mechanics, and electronics could fail, not to mention that a head crash could wipe out good data. I'm extremely disappointed that the capacity of optical disc formats are essentially frozen, topping out at 100 or 128 GB for BD XL. They're definitely not keeping up with the continual increase in storage density and decreasing cost of hard disks and flash memory. Why are new formats not forthcoming? Where's my 300 GB Archival Disc? Where's my 1 TB holographic disc? Where's Microsoft's glass optical disc that's stable for millions of years? I want to keep on burning optical discs and putting them in cold storage, but this gradually obsolete technology is not making a convincing case for me today. Previously: https://news.ycombinator.com/item?id=26038893 https://news.ycombinator.com/item?id=26038893 , https://news.ycombinator.com/item?id=29221418 https://news.ycombinator.com/item?id=29221418

tinus_hn 5y ago
How many people are buying these 128GB discs? Probably not a whole lot and that is the reason why nobody’s going to make the investment to create bigger discs. If you want huge local offline storage, the solution is tapes.
- smackeyacky 5y ago
  Even lowly LTO2 is 400gb. Plus the reliability of long term storage of tape is much better researched.
- em3rgent0rdr 5y ago
  But it is already known that magnetic tape is much less reliable in long term storage. The author is looking for long-term reliability, not just huge local offline storage.
  - tinus_hn 5y ago

em3rgent0rdr 5y ago

Could do RAID 4/5/6 with Optical Disks too for additional paranoia. Ideally there should be some machine to go through old backups and upon first detection of an error, then it could regenerate the array from the remaining discs of that array.

tenebrisalietum 5y ago
Use PAR2 files, like Usenet does.
NavinF 5y ago
That’s the biggest problem with optical disks. With no automation, it’s totally impractical for one person to maintain a full backup of everything they care about. 100TB is like 2000 discs plus parity.
- em3rgent0rdr 5y ago
  Yeah. Though it is not difficult to build such a machine and similar machines have been around, such as CD Jukebox players and multi-disc burners.

gandalfff 5y ago

My biggest concern with Optical Disks is obsolescence and convenience. I bought some DVD media to do some backups but so far I have only backed up a portion of my photos. Right now my files are being stored on my MacBook's internal SSD, Backblaze, Google Drive, and a Time Machine backup on an SD card that stays in the SD slot. I do full backups to external hard drives every so often. I'm too lazy for any backup method that requires an involved process like optical media. And I also find myself asking if it's even worth it. I don't think my files are that valuable, to be honest. I would be sad to lose them, but it might also be freeing in a minimalist sort of way.

tambourine_man 5y ago

I had a different experience. A good fraction of the CD/DVDs burned 10-20 years ago won’t read. At least not trivially.

yeetsfromhellL2 5y ago

RO media is great, especially when you're concerned about data integrity and may not completely trust a machine writing or verifying the media. Consider you're downloading sensitive data from the internet, or just writing sensitive data on an internet connected machine (maybe it's OS installation media, or important legal or financial docs, or you're a wall street or NSA whistleblower, or it's a Bitcoin key backup), and you're worried your machine may be compromised on account of it being connected to the internet; you may not want to stake the quality of the rest of your life on your computer not lying to you about file integrity. What do you do? Write it to RO media and take it to different computers to verify the checksum/signature. You don't need to worry about other machines, which are also potentially compromised, corrupting the data. You also don't have to worry about something like BadUSB, where the USB device's microprocessor firmware infects the host machine (or vice versa) before the data payload is even read. This means you can put the disk in your secure airgapped machine at home, even after it's been in the machine at the local library. You create a concensus of file integrity after reading and verifying the data across a range of machines. Obviously there are other attack vectors, but with the cost of these sorts of attacks (badUSB, or simply getting rooted) going down, the accessibility going up, and the potential rewards becoming more valuable and widespread, it's an attack vector to consider for important data.

SnowHill9902 5y ago

What do you people need to store so much for so long? Backups are rolled-over ever few days. Personal photos and videos?

the_af 5y ago
Personal photos and videos indeed, I would guess. The one piece of data you can never get back or buy back if your only copy breaks down. Also, a kind of data that takes a lot of space, compared with, say, text documents.

fghorow 5y ago

When I was in grad school back in the '80s, 9 track magtapes were the standard for lots of things: backups and long term storage being some of them. (I still have one or two tapes in a box somewhere.) About 10-15 years ago, it dawned on me that I hadn't seen a working tape drive in quite a while. Any tapes, even if the media were intact (highly doubtful, and the point of the parent article) would not be readable. Much the same comment for boxes of punch cards. (My late colleague used to tear off pieces of the cards and use them for "filters" in his roll-your-own cigarettes.) I guess my point is, even if the media are reliable (holes in cardboard? pretty foolproof from an ink-on-vellum viewpoint) the entire surrounding ecosystem needs to survive for archival purposes.

ris 5y ago

Not very actively maintained these days but https://en.wikipedia.org/wiki/Dvdisaster https://en.wikipedia.org/wiki/Dvdisaster stores error correction codes in the remaining space on an optical disk, without affecting its readability by unaware systems.

lostgame 5y ago

Extremely lucky about this ‘100% success rate’. After dealing with several valuable SEGA Saturn games that succumbed to bit rot, and are therefore worth practically nothing - (nor are they playable, obviously) - I backed up whatever optical disks I had left and have never used optical media since. I certainly never will again. I just can’t trust it anymore as an investment. I’ve got vinyl from the 50’s/60’s that still play great but after losing those SEGA games I just see those little plastic disks as ticking time bombs.

eezurr 5y ago

Here's an older article on Disc Rot, for some counter points https://www.vice.com/en/article/mg9pdv/the-hidden-phenomenon-that-could-ruin-your-old-discs https://www.vice.com/en/article/mg9pdv/the-hidden-phenomenon... [1] https://www.howtogeek.com/682807/the-cds-you-burned-are-going-bad-heres-what-you-need-to-do/ https://www.howtogeek.com/682807/the-cds-you-burned-are-goin... [2] [1] https://news.ycombinator.com/item?id=21668184 https://news.ycombinator.com/item?id=21668184 [2] https://news.ycombinator.com/item?id=23979241 https://news.ycombinator.com/item?id=23979241

msie 5y ago

5.5 TB Optical Disc: https://www.bhphotovideo.com/c/product/1549173-REG/sony_odc_5500r_us_5_5tb_optical_disc_archive.html https://www.bhphotovideo.com/c/product/1549173-REG/sony_odc_... Drive: https://www.bhphotovideo.com/c/product/1549175-REG/sony_odsd380u_optical_disc_archive_gen3.html https://www.bhphotovideo.com/c/product/1549175-REG/sony_odsd... (only about $9k)

donatj 5y ago

I personally was going through a large binder of old backups this week that's been in my parents basement away from sun for 15 years. Many CDs and later DVDs. The DVDs were all seemingly fine but a sizable portion, maybe 20%, of the CDs are flaking along the outside. I was honestly kind of surprised.

namibj 5y ago

9ct/GB for plain BD-R is a rip-off. They cost 0.08 USD a piece (if you reach MOQ on Alibaba), plus about the same as patent license fees. So 16ct/25GB, not 9ct/GB. Taking storage overhead (cases of some sort; spindles aren't well-suited to store BD long-tem) into account, the Chinese 20ct/50GB (plus patent; iirc sub-linear scaling with capacity?) option of a DL BD-R may easily be cheaper over all.

R0b0t1 5y ago
My costing put it as positive compared to disk even without massive discounts, but physical volume is a problem, and cheaply constructed disks are volatile. There's an open space for cheap tape drives.

codezero 5y ago

I wish I did more rigorous work on this but I managed a large Rewritable DVD backup for a satellite instrument with over 3000 DVDs stored in a filing cabinet for almost ten years. When I joined about three years in I added checksums to the backups and infrequently sampled and reburned older discs and found zero corruption after almost a decade stored in those conditions. Given there was a mix of R and RW burned discs I was actually pretty surprised there was no corruption because I had it ingrained in my mind these things shouldn’t last so long.