I have just started learning about AWS and come to know AWS S3 has several choices (example: S3 standard, S3 glacier). In general, I believe storages where we can get files faster are more expensive, and those where we can get files slower are cheaper.
I would like to know how this works in terms of technology. Why is the cost lower (probably for Amazon) if the reading speed is lower, and vice versa?
Glacier is an archival data store. It is meant to store data which is very rarely accessed, primary for backup purposes. Exact details of how AWS stores its data are unknown, but its speculated it is stored and shelved on custom tape storage, or something similar, which is much cheaper then any regular hard drives used for frequent data access. Wikipedia writes:
The Register claimed that Glacier runs on Spectra T-Finity tape libraries with LTO-6 tapes.[10][11] Others have conjectured Amazon using off-line shingled magnetic recording hard drives, multi-layer Blu-ray optical discs, or an alternative proprietary storage technology.