Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

canada.ca

Post reply on HN
Print view View original

171–180 of 204 posts

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

#171

Post by gruez »

smarx007 wrote: post #104

Is anyone using M-disks and what's your experience so far? https://en.wikipedia.org/wiki/M-DISC https://web.archive.org/web/20130422110903if_/http://www.mdi...

There's allegedly nothing different special about blu-ray M-DISCs

>Digging further around the M-disc site, it is noted that their section on longevity testing actually features no data about the BD-R discs at all. Indeed, if there were tests, the reports were not actually featured on the site at all. Further poking around in M-Disc Technology pages shows only references to their DVD products. In fact, it seems their patented “etched in stone” material may only apply to their DVD products.

https://goughlui.com/2015/10/16/review-tested-verbatim-lifet...

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

#172

Post by j_not_j »

Beware of silent corruption in your disk arrays.

https://www.nsc.liu.se/lcsc2007/presentations/LCSC_2007-kele...

Disks didn't always write a block in the correct place. Things are better now, but still not perfect.

I would recommend that you read all your data all the time; this ensures RAID-1 or ZFS will correct the silent bitrot. Hopefully. A megabyte or two per second read rate is all you need.

See the pdf for more. There is a git archive at https://gitlab.com/fsprobe for a reader utility.

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

#173

Post by mixmastamyk »

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…

CD-R’s after 2020?

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

#174

Post by dehrmann »

loeg wrote: post #116
acomjean wrote: post #113

Earlier quoted context omitted.

Could you explain the PAR file and why that would help?

PAR files are a form of Forward Error Correction (FEC) (implemented with Reed Solomon). They can be used to repair some percentage of damaged blocks in a file or set of files. The percentage is determined ahead of time when you generate the FEC (PAR files) and imposes the same amount of storage overhead (i.e., 15% redundancy costs 15% additional disk space with Reed-Solomon). https://en.wikipedia.org/wiki/Error_corre…

CDs already use Reed Solomon, though. But yes, you can double it up.

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

#175

Post by dehrmann »

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…

What's crazy impressive is this was a CD-RW, not a CD-R.

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

#176

Post by justsomehnguy »

GnarfGnarf wrote: post #136

I can still read my backup CDs from 1998. I recently invested in M-disk DVDs and a compatible burner. Not cheap ($10/disk), I only use one every other month, I use the regular DVDs the rest of the time. BTW I calculate and write MD5 checksums on the backup DVDs, so each file can be validated years from now.

> MD5 checksums

Better do recovery records, that way you would able to recover data and not only know it was corrupted.

RAR recovery records, if storing in an archive is okay, or PAR.

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

#177

Post by vorpalhex »

gruez wrote: post #170
bitL wrote: post #156

Earlier quoted context omitted.

M-Disc are supposed to last 100-1000 years. They literally engrave data into an inorganic layer with high melting point instead of writing to a dye.

>They literally engrave data into a polycarbonate with high melting point instead of writing to a dye. Are you sure you're not talking about pressed (ie. mass produced) discs? I find it unlikely that a blu-ray/dvd burner equipped with only a laser can "engrave data into a polycarbonate with high melting point".

> Verbatim M DISC™ optical media is the new standard for digital archival storage. Unlike traditional optical media, which utilize dyes that can break down over time, data stored on an M DISC is engraved on a patented inorganic write layer – it will not fade or deteriorate. This unique engraving process renders these archival grade discs practically impervious to environmental exposure, including light, temperature and humidity.

https://www.verbatim.com/subcat/optical-media/m-disc/

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

#178

Post by bitL »

gruez wrote: post #170
bitL wrote: post #156

Earlier quoted context omitted.

M-Disc are supposed to last 100-1000 years. They literally engrave data into an inorganic layer with high melting point instead of writing to a dye.

>They literally engrave data into a polycarbonate with high melting point instead of writing to a dye. Are you sure you're not talking about pressed (ie. mass produced) discs? I find it unlikely that a blu-ray/dvd burner equipped with only a laser can "engrave data into a polycarbonate with high melting point".

See https://www.m-disc.com/technology.html

"The M-DISC engraves data into a patented rock-like layer that is resistant to extreme conditions of light, temperature and humidity"

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

#179

Post by vorpalhex »

magic_hamster wrote: post #152
bitL wrote: post #122

Earlier quoted context omitted.

100GB M-DISCs are still pretty decent archival means. All photos/videos I've ever generated are roughly 1.2TB so that's 12 of those M-Discs.

Those are BD-R. According to the linked research, those will last 5-10 years, or up to 20 years if you're using a gold metal plate. Either way, they're not close to top performers that last 50 to 100 years and more. I'd suggest creating multiple backups, including additional mediums such as hard drives and cloud storage (something like S3 Glacier Deep Archive could be relevant), and refresh the media periodically.

M-Disc is BD-R compatible but operates under a different set of principles.

Their claim is 100+ years. So far testing seems to generally support that claim but that is all simulated aging.

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

#180

Post by loeg »

dehrmann wrote: post #174
loeg wrote: post #116

Earlier quoted context omitted.

PAR files are a form of Forward Error Correction (FEC) (implemented with Reed Solomon). They can be used to repair some percentage of damaged blocks in a file or set of files. The percentage is determined ahead of time when you generate the FEC (PAR files) and imposes the same amount of storage overhead (i.e., 15% redundancy costs 15% additional disk space with Reed-Solomon). https://en.wikipedia.org/wiki/Error_corre…

CDs already use Reed Solomon, though. But yes, you can double it up.

33% parity, apparently.

https://en.m.wikipedia.org/wiki/Cross-interleaved_Reed–Solom...

Post reply on HN