The Amazon Glacier Secret is hidden in plan sight.
I think is just a virtual product. Probably unused S3 capacity, at a much lower price, not a different technology.
Maybe Glacier stores in the unused parts of S3 disk sectors, the empty part of the last sector of files that don't completely fill 512k. Takes 4-5 hours to retrieve because it has to pull without impacting dozens or hundreds of S3 drives.
