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I've many times heard things along the lines of:

Those CDs/DVDs won't last forever. In fact, the data will be gone/corrupted in just a few years.

Does this apply only to discs that were "burned" by consumer equipment, i. e. a disc burner in a PC?

Or does this also apply to professionally, industrially "pressed" discs? For example, a game sold in retail on CD-ROM, or a music album sold in the 1980s on CD and now in the shelf somewhere in a house, or a demo disc bundled with a computer magazine in the mid-1990s which I want to test in like 2025 or whenever I finally get a house with a room where I can build a classic PC and try it out after all these years? (I tried in emulators, but they are all garbage.)

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  • $\begingroup$ So what does last? 5 1/4" floppies? 3.5" diskettes? SCSi harddrives? USB Sticks? All storage we use is ephemeral... $\endgroup$
    – Solar Mike
    Sep 5, 2021 at 20:07
  • $\begingroup$ @SolarMike Not sure what your point is? $\endgroup$
    – Torez
    Sep 5, 2021 at 20:15

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I don't think it is a question of "consumer" vs. "professional" but really "burn" vs. "press". "Burning" a CD (or other optical media) is fundamentally different from "pressing". That is quite different from magnetic media (at least floppy disks, hard drives, tapes) where, AFAIK, there is no fundamental difference between individual production and mass production - just a big speed difference.

There are some low-volume "professional" CDs or DVDs (e.g., databases or other information distributed at high prices but low production volume) that are burned (pressing becomes more cost-effective at high production volumes - much like laser printing vs. offset printing), but generally speaking a mass-market game, music CD or movie DVD will be pressed, not burned.

With a bit of searching I found plenty of reports ranging from blogs and forums to abstracts of journal articles. But the bottom line seems to be that burned media can be expected to be reliable on the order of 20 years, though possibly much longer, and that pressed media can be expected to be reliable for hundreds of years, but sometimes less. There is a lot of variability depending on temperature ("refrigerator" temperatures seem to be the best), exposure to chemicals and other factors.

My hunch is that it is likely an order of magnitude of usable lifetime between typical burned media and typical pressed media, but with a lot of variation. What I would definitely avoid for archival purposes is any kind of rewritable media - by its nature that is going to be most susceptible to damage as it is designed to be erased.

Unfortunately, many of the problems with any digital storage media is related to size, and capacity and cost are also related to size. Punched cards are very reliable (especially if numbered so they can be put back in order and if they contain both printed and punched versions of the same data) but very expensive and bulky. Magnetic media spans a wide range but the denser it gets, the more susceptible to stray magnetic fields. Semiconductor memory (e.g., flash drives) costs less and stores more if the cells are smaller but also becomes more vulnerable to radiation and electrical problems. I suspect optical media will have similar problems in the progression from CD to DVD and beyond.

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  • $\begingroup$ You should add the difference between a pressed disc and a burned disc: a pressed disc is literally indentations into plastic that is pressed by a glass master, whereas a burned disc is a dye that is darkened by a laser. Pretty obvious which one is going to be more durable. The discs have to be sealed properly though and there's a particular variant of DVD that is made specifically for archive which should last longer (might have been DVD-RAM). $\endgroup$
    – DKNguyen
    Sep 6, 2021 at 6:03

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