S3 Glacier Deep Archive is probably the closest to a tape warehouse, at the standard rate it would cost $99000/month to store 100PB of data.

$0.00099 per GB per month * 100,000,000 GB = $99000

You need to account data transfer OUT if you need to get your data from S3. _If_ you could download 100PB data, it'd cost you $1M.

Hopefully it is not stored as one giant object and hopefully your retrieval would be only specific parts (small parts.)

You’d want to do some research on getting data out of glacier. I’ve read some nightmare stories about the bill from trying to get a small amount of data out of glacier. I can’t remember the details, and some of the large cost was people sort of doing it wrong. But some of the tooling makes it easy to do wrong.

When I was using glacier, we treated it sort of like a write only storage, with the understanding that if we ever needed data out, we’d have to think long and hard about the data’s value, and probably would have gotten an AWS rep on the line to make sure we didn’t do anything stupid.

Is your tape library stored redundantly across multiple data centers?

Unfortunately I don't have access to that info, sorry!