When Discs Die | Hacker News Reader

When Discs Die

tedium.co

69 pointsimartin2k47 comments

Back when hard disks were expensive and CD-R(W) discs (relatively) cheap, I used to do backups and move less used stuff to CD's. A number of years later when this was no longer true (and CD's were becoming laughably small) I moved all the data back to hard drives. In the process I discovered that a fairly large fraction of the discs had developed some minor corruption. Luckily I was able to recover the vast majority thanks to GNU ddrescue ( https://www.gnu.org/software/ddrescue/ ).

The bottom line is that for long term preservation you really need to keep multiple copies, preferably on multiple mediums, and regularly check and recopy them before the medium gets so obsolete you can no longer access it.

(Yes, I realize the article touches factory pressed discs rather than CD-R's although there is a short mention of such discs too)

par2 is another alternative for redundant copies: https://github.com/Parchive/par2cmdline

It's kind of like RAID for data, and removes the uncertainty that maybe ddrescue wouldn't get an I/O error and just receive and save bad data (it happens). It'd also be capable of repairing damage, up to the redundancy level par2 archives are created at (default is 5%, can go all the way to 100% -- which would mean you don't need any of the original data assuming all par2 files are not corrupt either (which it can also handle...)).

I wonder if there is some sort of archiving software that is able to encode parity bits similar to how RAID5 works in order to help recovery in the event of corruption to part of the disk.

You can use WinRAR with zero compression and recovery volumes.

This is useful if you have a bunch of little files - you WinRAR them into a single file with recovery volumes, and then you can create a bunch of PAR2 files on top.

I'm not saying this is a sensible thing to do.

See sibling post about PAR2.

This knowledge should be more widespread imo, pretty sure there are still people out there assuming CDs are like indestructible. Once I started a job and after a couple of months I discovered there was a closet containing hundreds of CD-Rs all neatly labelled and seemingly containing things like fMRI data used in research. You should have seen the faces of colleagues and the guy responsible for the backups of their data when I told them CD-Rs where not exactly the most durable way of storing important data. (I figured this out because of the very first audio cd copies I had started to develop unexplained errors). They didn't believe me so I randomly picked a couple of discs and like the third one was completely unreadable (I/O errors on ls or so, don't remember).

Gosh I remember how many IO errors occurred on those early and / or cheap CD-Rs like 'Transonic', 'TDK', 'Maxell' and all those other dreadful light green or light blue coloured Cyanine ink based coasters. I remember trying to backup my MP3 collection many, many years ago and trying to afford tens upon tens of decent quality Verbatim or similar brand discs and burning them slower than their top rated write speeds in an effort to make them as durable as possible.

I remember getting my first 40x or 50x writer, that thing sounded like it was going to blow apart at any moment, I think I used to limit write speeds to a maximum of 16-24x at most.

And then hard disks (or hard discs which I believe is an equality technically valid spelling) started to drop in price, ended up with a pile of those quantum fireball 850's, if you had these you'll remember having to 'tap' them on the top to help them spin up as I assume the baring fluid / grease would harden enough to prevent the drives from spinning up if they'd been powered down for more than a week or so.

There are works out there where the master tapes have long since vanished that we can only enjoy today by virtue of the durability of the vinyl/shellac the original copies were pressed upon. It's scary to consider how more obscure digitally-issued releases risk evaporating entirely.

I dismissed analog purists like Steve Albini as cranky old men until recently, when I realized they have a real point w/r/t preservation.

The major film studios already do this: they create a tape print (this process is one of the only reasons Kodak still exists) of every film, including digitally shot/processed ones, and store them underground. A hard drive might die in 5 to 10 years but film is guaranteed for 100.

I bought my first CDs in 1984, and played them on the world's first CD player - the Sony CDP-101. Of the hundreds of discs in my collection, I had maybe 3-4 from that decade go bad. What worked for me was storing them in the jewel boxes on edge (not laying flat), indoors away from sunlight.

So far as "Disc Rot", as a former LaserDisc owner, I'm very familiar with it. On the 12" platters the glue between sides could fail and sometimes lift the aluminum recording surface off the plastic. Or the edge seal would fail and oxygen would turn the aluminum into aluminum oxide. Both would make a $70 movie (in 1988 dollars!) unplayable.

I'm sad to see CDs go. As has been told, they're the first recording format that was replaced by one with inferior sound. I never had many LPs, and don't have the storage space for them, but I get that they get the listener more involved - you have to consider which album to listen to and set aside 50 minutes (including the side flip). You can't just hit "random play" and walk away. So it's nice to see them make a comeback.

I still have a German-made The Doors - The Doors CD with orange silkscreening and uncommon metal layer from edge-to-edge with a date of 1982.

Helloween - Keeper of the Seven Keys, 1987, original, 1987 disc. If thought it was a cheap ripoff when I bought it in ~2003, because the inlay is full of CD specs and things about CDs, only to realize the date in the disc is actually the real thing.

Still working, and I used to listen to that a lot. German as well.

> As has been told, they're the first recording format that was replaced by one with inferior sound.

What about records largely getting replaced by 8-tracks and cassette tapes?

In the long-run streaming services will move towards higher fidelity audio as bandwidth costs decline on both sides. Tidal already offers the option. I also suspect the vast majority of listeners can't even tell the difference between 320 Spotify, 256 Apple, and lossless Tidal, let alone care enough about the differences to switch services.

I don't think tapes replaced LPs so much as supplemented them. With the exception of the car-mounted record player that was an option on some Chryslers[1], the advantages of 8-track and cassette were their ability to take your music with you on the road. I still listen for the "clunk" of the 8-track player changing tracks in the middle of Rush's YYZ..

I think the bandwidth problem of providing high-quality streaming music could be solved by a peer-to-peer system (put your already-downloaded library online for others to listen to). But the record companies would strenuously object -- with good reason, even even if access were controlled via encrypted subscription.

[1] http://www.consumerreports.org/cro/news/2014/04/record-playe...

CDs had a big problem with mastering. They either have a bad sound from CD being a new format (Zappa 80s CDs suffered from this) or since the mid-late 90s are brickwalled to hell thanks to the loudness war.

Obviously there are plenty of fine CD versions of albums out there, but I heard enough poorly mastered CDs and spent enough time searching 2nd hand stores for known good versions to not be worried about the format going away.

> CDs had a big problem with mastering.

You are correct. Lots of the early releases once the goldrush started still had their RIAA equalization on them (aka "shovelware"). Even those that used original sources simply didn't sound all that good because of the mastering engineer's inexperience (first release of The Wall, I'm looking at you). There were still gems made though, like Brothers in Arms

Because of the loudness war, I've started looking for earlier releases on discogs.com. Anything listed as "Remastered" is viewed with suspicion.

https://en.wikipedia.org/wiki/Loudness_war

Few years ago I bought a new DVD drive and it came with a CD that claim to last for a 1000 years. [1]

I really wish I could test it, but I lost the disc already.

[1]:https://en.wikipedia.org/wiki/M-DISC

If there were a CD that guaranteed I would be able to use it in 1000 years, I would buy it in a minute!

This is the company that makes em. http://www.mdisc.com/

I think Stratoscope's point was the guarantee that Stratoscope could still use it in 1000 years (IOW, that they'd still be alive then).

Bingo! I would pay just about anything for that CD...

Tell us how it goes! Looks like they sell special DVD or Bluray burners for M-Discs

Set a reminder for 1000 years from now, and I will tell you how reliable they really are.

They've been around for 5 years and good quality brands support them. Maybe they won't last, but it's a better gamble than a pack of cd-r discs from walmart!

Let me be a little more explicit. Stratoscope was willing to purchase the disc on the promise that Stratoscope would personally be able to read the disc 1000 years from now.

IOW, not just that the data would be there and readable, but that Stratoscope (the person) would also have lived another 1000 years.

Ahaha that blew right over my head!

http://www.zdnet.com/article/torture-testing-the-1000-year-d...

They claim to be immune to data rot:

http://www.mdisc.com/mdisc-technology/

This is my nightmare, I spent years collecting for a full PAL Sega Saturn collection. Reading 'disc rot' in any form always reminds me I need to prioritize ripping my collection sooner rather than later.

But when I learned about this problem, I checked my several hundred discs between Sega CD, Turbo CD, Saturn, and even Dreamcast games and found DOZENS had this problem. Several expensive games I owned were mint—except when held to the light I could see one or more little white dots that proved my game had damage. Some of these I went back to play after not touching for years and found they now would occasionally lock up or not play at all. I had a few FACTORY SEALED games that I opened and found the same thing.

It has been a nerve-shattering nightmare for a collector like me.

So should I worry about my factory sealed copies of FF7 and Xenogears? Also, is there any sort of "rot" that may occur with cartridge-based items? I have some unopened NES and SNES games as well.

Never thought about it, but if you're a collector of some sort you would be pissed to see your collection destroy itself through no fault of your own

If you backup your data (on whatever media) I'd recommend to use some kind of bitrot detection tool. For example https://github.com/laktak/chkbit

When you later restore you will at least know if/what is damaged. Multiple backups help too.

Never liked the CD/DVD physical medium.

Convenient, yes. Sounds great too. But far more prone to physical damage (scratches, etc) than tapes or records, in my personal experience. Lost count of the number of times a $20+ movie was destroyed after being in a childs hands.

Mini Disc or cassette seemed better because there were a case around the support that was making harder to damage it. If for some reason, a cassette was broken, it was still possible to move the tape to another case (tricky but not impossible, nice little hacks needed).

People got too fascinated by the shinny colorful reflection of CDs.

fascinated by the shinny colorful reflection of CDs

And then later on even more fascinated with the production of all black cd's etc. To be honest, I like those as well, probably just beacuse it's something different.

And yes there's something to say for the sturdyness of MD and the 'openness' (almost open-source like lol) of tape.

Mini Discs use a different process than burnable cds. I think its more robust, but I can't verify. My 20 (yikes) year old minidiscs all work fine, when I dug them out of storage and tried them.

Tapes can go too. Depending on the binder the tapes have to be baked to restore them. (Video and audio tapes may suffer from this).

When CDs came out people really liked them. They sounded great and didn't involve the care needed with records or tapes (cleaning records and tape pinch rollers... ug). You could skip to any track without flipping it over. Minidiscs came out many years after cds. Records probably are the most archival since its music in physical form.

Leaving a VHS in the hands of a child would've yielded similar results, with records most likely the same.

>Lost count of the number of times a $20+ movie was destroyed after being in a childs hands.

As opposed to a tape or records? I've scratched records trying to remove dust.

On the subject of discs, I just realised I can't actually remember the last time I used CD / rotational optical media of some kind, I honestly can't! If I had to guess what the reason for it might have been I'd probably go with some obscure band (music) that only had physical distribution - but generally in those cases (no pun intended) I'd most likely but the CD to support the artist then check on what.cd (R.I.P) (pun slightly intended) and saved myself the pain of finding an optical drive and ripping it into my collection. It's likely it would have been something like that I think.

Sorry for being a bit off-topic there but it was a bit of a 'oh, wow!' moment.

Thinking on the 3-2-1 backup strategy[1], the "2" refers to "two different mediums". Some say that means two different hard drives, but with articles like this I argue that it should be "two different forms of media."

Of course, that's just referring to my personal data. With media like what is covered in the article, copyright law (incl. the DMCA) comes in to play, potentially limiting your options.

[1]: https://www.carbonite.com/en/cloud-backup/business/resources...

A related question is when flash memory dies.

Replaced by what?

Memristors?

In about 5 years they start losing charge, and there is no return from there. Magnetic storage last longer usually, tapes ~20 years, but they require certain conditions and it does matter if you store them vertically or horizontally. Hard drive can last very long, but they have moving parts, which is a completely different world of potential problems if they are power off for a long time.

I dug into archiving my stuff a few months ago, ended up using single layer panasonic blu-ray. They used to be advertised as 50 years archival grade, but panasonic split it into on that's without the archival label and one with - the latter is nearly impossible to get in Europe and is very expensive. We'll see in 10-15 years.

Mdisc, mentioned earlier, could do 1000 years in clinically-proven accelerated aging tests and withstood hard weather fairly well:

http://www.mdisc.com/

http://www.zdnet.com/article/torture-testing-the-1000-year-d...

There are numerous studies and accelerated aging test on CDs and DVDs, but I couldn't find anything similar to Blu-Rays yet, though I would be interested:

http://www.thexlab.com/faqs/opticalmedialongevity.html

It might be worth mentioning that 'Archival Disk' is a thing now, with 300GB-1TB capacity from joint efforts of Sony and Panasonic, but it's completely out of the consumer pricing for now: https://en.wikipedia.org/wiki/Archival_Disc

Man... this post makes me want to go rip all my old disc-based PC games, but... I don't even have an optical drive in my PC anymore...

That's easy to fix. External drives are pretty cheap (~$25 for DVD). Or you can track down ISOs, even for fairly obscure things, various places online.

Cheap bootleg DVDs from China often experienced rapid rot because of poor quality control.

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