Very Long-Term Backup (2008)
M-DISC Blu-Ray discs are still one of the few affordable options for long term storage if the amount of data you want to preserve matches the medium's capacity of 100GB per BD-XL disc. They should last 100 years or more ("up to 1000 years"). The 100GB BD-XL discs are quite expensive however (14€ each). They also seem to get harder to find.If you have less data you can go with the 25GB M-DISC Blu-ray discs (more drives can read these) or even with their DVD-R discs.Make sure to keep an external optical drive with USB-C around as well. I know that none of my PCs from the last 5 years had a builtin optical drive.If you have more data, consider LTO drives and copy them every 5-15(?) years.