Did anyone ever figure out what Amazon Glacier uses? They only publicly talk about using custom software to "optimize the sequence of inputs and outputs"...[1]
Say a cloud vendor needs a bunch of HDD for a database workload with high IOPs. Using modern disks (4+ TiB) this leaves a lot of stranded disk storage that can only be used for low IOPs workloads.
Archive storage uniquely meets the criteria of lots of storage, yet low IOPs.
Disclaimer work for Google but have no knowledge of how AWS glacier works.
The telco equivalent was ISDN, where a single linecard with two sub-rate ports might be sold to a bank, and a domestic user. The bank could (and would) demand card reset 24/7 to restore service to their ATM, the domestic user simply lost carrier, and game state.
Though a comment on that page mentions this HN comment claiming custom low-speed HDDs: https://news.ycombinator.com/item?id=4416065
This doesn't mean that they seem simply superior, though. I imagine optical discs have way better seek times, for example, even if read/write speeds are better with tape.