Amazon Glacier runs on BDXL disc libraries (like a tape library). There's nothing truly expensive about producing BDXL media, there just isn't enough volume in the consumer market to make it worthwhile. If you contract directly with suppliers for a few million discs at a time, that's not an issue (you did say high-volume, right?).
https://storagemojo.com/2014/04/25/amazons-glacier-secret-bd...
For medium-scale users, tape libraries are still the way to go. You can have petabytes of near-line storage in a rack. Storage conditions are not really a concern in a datacenter, which is where they should live.
(CERN has about 200 petabytes of tapes for their long-term storage.)
https://home.cern/about/updates/2017/07/cern-data-centre-pas...
If you mean "high-volume for a small business", probably also tapes, or BD discs with 20% parity encoding to guard against bitrot.
Small users should also consider dumping it in Glacier as a fallback - make it Amazon's problem. If you have a significant stream of data it'll get expensive over time, but if it's business-critical data then you don't really have a choice, do you?
