Music. I have some data CDs I burned in the mid 2000s, that I booted up a few years ago (Linux live CDs). I don’t have any data CDs from the 90s though. IIRC, ISO 9660 does have error correction.

Edit: I just looked it up. ISO 9660 doesn’t have error correction, but the underlying system, CD-ROM Mode 1, does have error correction.

Data CDs actually use even more robust error correction since they use interleaving in addition to FEC since they don't need to scan in "real time"

High capacity SD have a miserably failure rate with regular use. In PI's and dashcams many only get a couple of years before they start having errors. USB thumb drives do better but they have heat problems. neither are great for backups unless you just do a lot of write once and store

Today? Of course. But until recently that wasn't the case. Longevity though.

We got prediction of sector failure rates on HDDs and magnetic tapes down to a science. Makes archiving really easy as you know with statistical significance how often to test, copy and move data, to preserve it virtually forever (as long as there is someone maintaining the archive).

Solid state memory can be extraordinarily dense, but the denser it gets, the more it's prone to corruption and failure. Worse still, when solid state fails, the whole storage unit becomes obsolete, and data gets nightmarishly hard to extract, maybe even gone forever. Only with very rare and specialized workshops that have the equipment to do it. On the other hand, I've seen technicians recover data from tapes that were literally in a fire, right there on the field with bog standard equipment.

When you factor in that the average cost of a terabyte of magnetic storage is less than half of the average cost of a terabyte of solid state, then a few cubic centimeters of space per unit become practically irrelevant. Corporate settings actually prefer more smaller storage units than larger, as they cause less trouble when they fail. Redundancy is a numbers game.

eBay and the 1980s may be helpful

DIY Tape Drive:

• Keep the core-rings remaining from sticky tapes that you use.
• When you are about to finish your fourth, save some tape
• Peel the remaining tape and encircle 2 of the core-rings
  • Do the same with the other 2 core-rings and remaining tape
  • You might want the amount of tape used to be same for both the pairs
• Connect core-rings to the axle of your choice