How Long Will CD's and DVD's Last?

Factual Questions
21

You may be thinking of the Blu-ray manufacturing process, not CD or DVD.

It’s been quite some time since I was involved in manufacturing optical discs, but I remember that there were at least two, perhaps three widely used processes that were used for BD. Singulus had one method - Origin another, and perhaps a third that used a punched film for the cover layer of the disc, not the data layer. In some of the systems, the cover layer was created using spin coated UV lacquer, similar to the spacer layer in DVDs.

All three - CD, DVD and BD - use injection molded polycarbonate against a stamper for the data layers.

In BD, the tricky bit is protecting the data layer, and ensuring an absolutely even thickness across the surface of the data layer since this is actually the read side of the disc. Hard to do with spin coating (but cheaper), but easier with a pre-manufactured film (but more expensive).

Even trickier is adding a second data layer.

CD and DVD are manufactured now as they always have been.

Also, sorry: pits aren’t etched into the glass master - they are exposed into photoresist, developed and then metallized, similar to semiconductor manufacturing.
Then a “father,” “mother,” and a “stamper” can be grown in electroforming.

22

OK, so I have an entire collection of CDs, cassettes and VHS tapes (or what remains of it - this actually occupies only part of a shelf on a bookshelf) in the garage of my parents’ house. These have been there through five Canadian winters - at times that unheated garage can be absolutely freezing. Could that have an effect on any of these recordings? If I bothered to have them sent over to me, what are the chances that they would still be playable?

23

I have no idea, but in your position, I’d neither assume that they are nor assume that they aren’t.

24

Yes. An unheated garage with harsh winters is the worse place store any storage media. Optimum conditions for magnetic tape, optical discs, hard drives, SSDs, flash drives, SD cards and analog film is cool, constant temps, low humidity, dark (for optical discs and film).

25

BTW, I would be remiss not to include this. How long do they last in a fireproof box? Obviously the company (Sentry) claims that they will. But I do have a fireproof box. And there are some CD’s and DVD’s that I just couldn’t live without (mainly family pictures and home movies).

And rather off-topic, I have all my most important family pictures saved on photo sharing websites. I mean, what could happen to them there? Family movies though I haven’t found a separate place for (they’re rather long). So I guess I must go back to the fireproof box. :slight_smile:

26

They will last just as long in the fireproof box as they would outside the fireproof box. Unless there’s a fire. The fireproof box is not going to protect against long-term deterioration of the aluminum coating due to oxidation, humidity, temperature changes, etc.

27

“Claims they will” what? I suspect the claim is that it will protect them from fire. A fireproof box isn’t magic. You can’t put a baloney sandwich in a fireproof box and expect it to still be edible five years later.

If you just can’t live without them, you need to have backups, preferably on more than one medium (e.g. DVDs, hard drive, cloud storage). Check relatively frequently to make sure your copies are still accessible and readable, and if you find one that isn’t, make new backups.

28

Yes, that’s what I’ve always done for things. Multiple backups. Sometimes if it is small stuff more than one copy on each disc or lots of parity data in case only part of a disc is unreadable. I have files now on flash drives that have passed through floppies, CDs, and DVDs over the decades.

29

Mega.nz is a great site. Gives you a free 50 GB.

30

Oh yee of great faith in someone else’s computer, which is what cloud is.

The OVH datacenter fire in France took down millions of websites when the datacenter was destroyed. https://www.searchenginejournal.com/ovh-data-center-fire-darkens-thousands-of-sites-worldwide/398485/ Those who had unmanaged servers, i.e. they were solely responsible for the own backups, but didn’t do it, lost everything.

Even if the datacenter/website has a backup of your data, unless you’re in the top tier of their paying customers, recovery is very low on the recovery list. If a catastrophe hits a bank and you have a safety deposit box there, you valuables may still be there, but it will be a long time before it’s recovered from the rubble.

Ad supported photo sharing sites go out of business all the time, sometimes without notice. Simple reasoning, if they can’t make money off you, they’re under no obligation to retain your data.

Starting in on June 1, 2021, Google will be severely restricting use of the free Google Drive, most critically:

If you go over your storage quota

** You can no longer upload new files or images to Google Drive*
** You can’t back up Original quality photos and videos to Google Photos*

## About Google Account storage

Someone else’s computer…their house, their rules.

Each Google Account includes 15 GB of free storage quota, which is shared across Gmail, Google Drive, and Google Photos. You can add to your storage quota by purchasing a Google One membership (where available). Occasionally, you may receive free additional quota from a special promotion or related purchase. To learn more about your quota, see what items count towards your storage.

## What affects your Google Account storage

### Prior to June 1, 2021

#### The following items count against your storage quota

** Original quality photos and videos backed up to Google Photos*
** Gmail messages and attachments, including your Spam and Trash folders*
** Most files in Google Drive, including PDFs, images, and videos*

#### If you go over your storage quota

** You can no longer upload new files or images to Google Drive*
** You can’t back up Original quality photos and videos to Google Photos*
** Your ability to send and receive email in Gmail may be impacted*
** You can still sign into and access your Google Account*

How your Google storage works - Google One Help

Edit: Active and defunct photo sharing sites:

https://support.google.com/googleone/answer/9312312?hl=en

31

Remember that Mega.nz rose from the ashes of Megaupload which was abruptly shut down. Again, never put too much faith in someone else’s computer.

32

How long will my “Original Master Recording” of The Moody Blues album “Days of Future Past” last?

It’s a CD called an “Ultradisc” and apparently 24kt gold plated.

33

Just as a data point (the singular of data is anecdote) I digitized several of my Von Karajan Beethoven Symphonies a few weeks ago, those discs date to the mid-to-late 1980’s and as cheap replications of much old recordings were not made any better than average. Plus, a recording of his 9th made in Japan, the second disc I bought (1985) so old it has sub-tracks on it. None had problems reading. For the last decade and a half, these have been stored in my cool, low humidity basement; before that in my living room, mostly room temps.

And just for a side note, I can’t remember how many years since I bought a CD last. Quite a few.

34

:slight_smile: Have some of the same recordings.

I bought CD last week. But it is the same story. I bought it at a concert from the artist. Selling CDs is a way of making a bit more money, and I buy them to give the artists a bit more support. Many times the same CD is available on Apple Music, so I listen to a downloaded version for nearly free, and the actual CD stays in its case. It is easier than actually ripping the CD. My actual CD player is on a shelf in the cellar where it has languished for over a decade. It is depressing how much I paid for it.

A recent concert was selling download tokens. One bought a business card sized bit of paper with a unique code to download from Bandcamp. In the end the effect is the same.

35

For you, listening to it right now, sure. For long-term preservation, no.

From that perspective the answer to “will my CD last” is “it doesn’t matter; there were millions of those CDs distributed (or, at a minimum, thousands for the most obscure indie band).” At least one of them will last until an arbitrary amount of time. The underlying recording will never be lost.

What happens when Bandcamp goes out of business? If something is on one company’s server and you access it by streaming then there is effectively only one copy in the entire world, and when it’s gone it’s gone. Even moderately popular artists are on, what, maybe 20 servers? Apple Music has an array of disks, SiriusXM does, Amazon does, etc…however many places are selling it, that’s how many copies there are. Do we trust that any of those 20 places will last forever the way that some portion of 3000 discs in 3000 hands will?

I’m sure that the Beatles and Taylor Swift and Kanye will survive every server migration and change in audio format standards over the next 100 years. Will this be the case for artists who aren’t selling or aren’t worth negotiating extensions of the contract with? Will it be possible to listen to Heinali or Madeleine Peyroux or Julius Hemphill in 2121 without building a working CD player or turntable from old plans? Or will it be just like film where the move to the cloud has meant only the most popular content is available without seeking out physical media?

36

Online storage is a fine place for a backup. A flash drive, hard drive, or CD/DVD is also a fine place for a backup. None of these places is adequately reliable enough to host the only copy in the universe of your important files.

Working copies of my files exist on my PC, but I also update a backup on an external hard drive every month; that external drive is disconnected and powered down the rest of the time to protect from surges and hacking, but I store it near the PC for convenience, making it vulnerable to theft, fire, and tornadoes. Every six months I backup to a second external hard drive; this hard drive gets stored in a zip-loc bag inside a foam-lined hardcase inside a fireproof safe in the basement.

A good practice. When I write my new backups, I don’t delete the old backups; I have backup versions spanning several years now.

37

Especially a business run by some as shady as Kim Dotcom. Whereas there is not that great a chance of Apple, Google, Amazon or Microsoft going south anytime soon, putting one’s faith in someone with a only a passing acquaintance with business ethics is likely a trifle foolish.

There is little choice but to simply spread one’s risk. Someone else’s computer is a great idea if you can’t guarantee the safety or integrity of your own. I know of at least one person who came home to discover their computer, and all their backup disks (stored elsewhere in the house) all stolen. It pretty well ruined their business. Most people don’t have the technical wherewithal or the time to invest in managing their own resiliency. Most businesses I have dealt with run a combination of offsite archive and cloud backup.

Don’t confuse backup with archive or versioning.

I like to post this site. In the end it is a subtle avert for a backup system. But it is well done. It was created and written by a colleague of mine many years ago. He went on to make a successful company out of it.
Sadly the prose seems to have been hijacked uncredited elsewhere.

38

Versioning is easy enough to understand. But can you explain the difference between backup and archive?

39

That’s why I’m not worried about the lifespans of most of my CDs. They’ll probably last, but if they don’t, I’ll be able to buy (or otherwise obtain) new copies of those albums from somewhere.

Did you notice the word “download” in the bit you quoted? Once you download the music, it’s up to you to do whatever preservation or backup you think is called for.

40

Archive is preserving the entire state at a known time and keeping it forever. Usually (back when I did this sort of thing) this was done by pulling a full level zero (in Unix backup parlance) out and putting them in a safe store. It was a good way of forcing tapes out of the backup cycle, so you chose older tapes. Nowadays you keep that snapshot somewhere safe in some modern manner. Now you can go back even years after the event and see a snapshot of things.
It overlaps with versioning, but not much. Versioning is typically implemented at a higher level in the file system and does not protect you from some possible failures. You could in principle make an archive with a byte by byte copy of the disks.