Hi, I saw this thread and just wanted to add to the discussion about archive media. M-DISC is a good choice for long term archive media. They are available in DVD and Blu-ray. They are supposed to last 1000 years. They may or may not not last that long, but they are certainly a lot more durable than standard media. I have linked to the wikipedia article, and to the mdisc website. M-DISC media can be bought on Amazon, but only a few disk drives are listed to write reliably to them, so make sure you have a compatible drive to write to M-DISC.
M-DISC - Wikipedia
en.m.wikipedia.org