Longevity of Recordable CDs, DVDs and Blu-Rays (2020) • Hacker News Board

Re: Longevity of Recordable CDs, DVDs and Blu-Rays (2020)

#71

Post by gorbachev » Fri, Oct 07, 2022, 9:48 AM UTC

darkwater wrote: post #29

Totally anecdotal but just a month ago I opened a box from my last moving (ended 4 years ago...) and I found a CD-RW labeled "Backup 2001", which survived 5-6 relocations, even an international one. Well, I put it into an USB DVD player I have aaaand, it starts spinning and spinning and spinning, and nothing shows up in Nautilus. Looking at dmesg I see a few I/O errors on the device. Then, I try ddrescue [1], start e…

I recently got rid of all my CD-Rs I'd use for archiving back in the day. Moved everything to a NAS and dumped CDs.

The earliest CDs I had were from 1994 or so, though most were from early 2000s. They were mostly cheapest CD-Rs you could buy back then, so I was expecting most of them be completely unusable.

But most of them still read perfectly. I had maybe half a dozen (out of hundreds) that were completely unreadable, mostly due to peeling, about a dozen that were functionally unreadable, because there were so many unreadable files I couldn't save anything complete out of them, and maybe 10% that had less than 10 unreadable files on them.

I was surprised. I was really expecting almost all the early ones to be dead.

Re: Longevity of Recordable CDs, DVDs and Blu-Rays (2020)

#72

Post by brazzy » Fri, Oct 07, 2022, 9:49 AM UTC

masklinn wrote: post #37

OptionX wrote: post #20

What would one use as a media for long-long-term storage, taking only into account the resisiliance of the ability to read the data from it? For example if you wanted to store data in a time capsule for like 100 or 200 and you where ganrateed the people on the other side had a reader capable of reading whatever media, and whatever format you chose.

Paper is a good one but the media is low-density and fragile. Although pre-industrial forms of paper (e.g. cotton paper, or papyrus) might have more long-term resistance than modern wood paper. Fired clay tablets are much more resistant, but lower density (because clay), unless you use a dedicated press maybe (most of the ancient Near East clay tablets were actually fired fortuitously e.g. by a building burning down,…

> Although pre-industrial forms of paper (e.g. cotton paper, or papyrus) might have more long-term resistance than modern wood paper.

The problem is not wood paper as such, it's production processes that leave some acidic substances in the paper, which causes it to become yellow and brittle on a timescale of a few decades.

Acid-free paper will easily last hundreds of years, and is nowadays easily available.

Re: Longevity of Recordable CDs, DVDs and Blu-Rays (2020)

#73

Post by Paianni » Fri, Oct 07, 2022, 9:51 AM UTC

TedDoesntTalk wrote: post #34

Test0129 wrote: post #32

After quite a bit of research into this about a year back I decided to archive everything on archive-grade CD-Rs. 20-50 years is more than enough and realistically in the correct climate (a safe or something that humidity would have trouble getting into along with dessicants, etc) could last much longer. I evaluated magnetic tape, HDDs, and a few other options are CD-Rs are as good as magnetic tape (in longevity) and…

> Taiyo Yuden I have not been able to buy these in the last few years. Also, when I was able to buy them, one had to be careful of counterfeits. Do you have a source for them?

TY closed down their own disc manufacturing in 2015. Nowadays the CMC Pro line (with 'Powered by TY Technology' branding) is the closest you're going to get.

Re: Longevity of Recordable CDs, DVDs and Blu-Rays (2020)

#74

Post by masklinn » Fri, Oct 07, 2022, 9:52 AM UTC

mschuster91 wrote: post #49

masklinn wrote: post #37

Earlier quoted context omitted.

Paper is a good one but the media is low-density and fragile. Although pre-industrial forms of paper (e.g. cotton paper, or papyrus) might have more long-term resistance than modern wood paper. Fired clay tablets are much more resistant, but lower density (because clay), unless you use a dedicated press maybe (most of the ancient Near East clay tablets were actually fired fortuitously e.g. by a building burning down,…

> If your focus is on longevity above all else, then you can’t beat stone. Stone can degrade as well. Basalt can absorb CO2 [1], marble is vulnerable to acids [2], and generally acid rain is a huge problem for historic buildings [3], as is bird poop [4]. Probably the only material impervious to damage is diamonds. [1] https://www.geo.uni-hamburg.de/geologie/ueber-das-institut/n... [2] http://intlstoneworks.com/blog/2…

> Probably the only material impervious to damage is diamonds.

Diamonds burn, and have the same problem as precious metals: getting stolen and repurposed.

> Stone can degrade as well.

Yes, but that doesn’t mean you can beat it.

And obviously you’d pick your stone based it’s characteristics and the environment, you wouldn’t record your message to the next generation on pumice.

Re: Longevity of Recordable CDs, DVDs and Blu-Rays (2020)

#75

Post by brazzy » Fri, Oct 07, 2022, 10:02 AM UTC

OptionX wrote: post #20

What would one use as a media for long-long-term storage, taking only into account the resisiliance of the ability to read the data from it? For example if you wanted to store data in a time capsule for like 100 or 200 and you where ganrateed the people on the other side had a reader capable of reading whatever media, and whatever format you chose.

Get a manufacturer to make you a pressed CD using glass as a base layer and gold as the reflective layer. Glass CDs are actually a thing[1], and a gold reflective layer should not complicated the production that much.

I'd actually expect such a CD to last tens of thousands of years.

For your requirement of 100 to 200 years, a pressed (not burned) CD might well be sufficient if the storage conditions are optimal (cool, dry, no oxygen).

[1] https://www.engadget.com/2006-10-22-near-perfect-glass-cd-hi...

Re: Longevity of Recordable CDs, DVDs and Blu-Rays (2020)

#76

Post by mmwelt » Fri, Oct 07, 2022, 10:06 AM UTC

brazzy wrote: post #72

masklinn wrote: post #37

Earlier quoted context omitted.

Paper is a good one but the media is low-density and fragile. Although pre-industrial forms of paper (e.g. cotton paper, or papyrus) might have more long-term resistance than modern wood paper. Fired clay tablets are much more resistant, but lower density (because clay), unless you use a dedicated press maybe (most of the ancient Near East clay tablets were actually fired fortuitously e.g. by a building burning down,…

> Although pre-industrial forms of paper (e.g. cotton paper, or papyrus) might have more long-term resistance than modern wood paper. The problem is not wood paper as such, it's production processes that leave some acidic substances in the paper, which causes it to become yellow and brittle on a timescale of a few decades. Acid-free paper will easily last hundreds of years, and is nowadays easily available.

So, perhaps use acid-free paper and print the data as QR codes using a laser printer?

Re: Longevity of Recordable CDs, DVDs and Blu-Rays (2020)

#77

Post by kalleboo » Fri, Oct 07, 2022, 10:07 AM UTC

jl6 wrote: post #9

I used to be concerned about optical media longevity. I bought Taiyo-Yuden discs. I checked their integrity. I stored them carefully. But the format became obsolete (for me) long before the media degraded. Recordable discs are just too small for the backup use case I had. Optical drives are still available of course, but they are now rarely standard with a new PC or laptop, and soon will become specialist components,…

Just my photo library is over 1.5 TiB, there just not way to have long-term offline backups of that, you have no choice but to run and maintain a file server and cloud backups

Re: Longevity of Recordable CDs, DVDs and Blu-Rays (2020)

#78

Post by cm2187 » Fri, Oct 07, 2022, 10:08 AM UTC

As long as price per capacity / storage density increases exponentially, isn't the best solution to transfer your storage to a newer medium over and over rather than taking a bet on a long term durability of a medium that we have no way to test (and a bet on the durability and forward compatibility of the device to read it).

A single $500 20TB hard drive can contain 30,000 CD ROMS and 500 Blurays. Surely the economics are there.

Re: Longevity of Recordable CDs, DVDs and Blu-Rays (2020)

#79

Post by bibaheu » Fri, Oct 07, 2022, 10:11 AM UTC

neilv wrote: post #16

When I was using dual-layer DVD+R blanks for off-site backups, the folk wisdom on blanks I heard from someone who burnt discs a lot was: to get a particular type and brand, and make sure the unit had been manufactured in Singapore. The country/factory of manufacture was indicated on the packaging, but the SKU and UPC didn't reflect that. More recently, I looked into re-adding optical disks (this time, M-Disc at BD ca…

Hi, I do the BD M-Dics at home, with Linux, with 0 problems. What problems did you get?

Re: Longevity of Recordable CDs, DVDs and Blu-Rays (2020)

#80

Post by cm2187 » Fri, Oct 07, 2022, 10:18 AM UTC

DocTomoe wrote: post #17

yosito wrote: post #14

Earlier quoted context omitted.

"Hard drives" don't necessarily last any longer than a few years either.

Sure - but with HDDs, you tend to just move all your stuff during each update cycle, because the new generation then tends to have a multiple of the capacity you've had before. CDs/DVDs/... feel very much more like a "long-term" storage solution, even when it isn't. Maybe it's because you can put them in shelves and forget about them, much like books?

Plus your backup probably requires dozens of CDs and DVDs, and perhaps they then fit on a handful of 4TB drives, and perhaps now they fit on a single 20TB drive.

For me, my storage needs increase more or less linearly, but storage capacity increases exponentially, making every cycle easier, involving less drives.