The default tier of AWS glacier uses tape, which is why data retrieval takes a few hours from when you submit the request to when you can actually download the data, and costs a lot.
AFAIK Glacier is unlikely to be tape based. A bunch of offline drives is more realistic scenario. But generally it’s not public knowledge unless you found some trustworthy source for the tape theory?
I love the fact that I can’t tell whether this is irony or not.