Storage solutions for data centers.
I used to work on them about 5 years ago; back then, they were mostly 3U chassis with 1 or 2 Gb fibre and 16 x 7200 RPM SATA drives attached to some sort of converter in the caddy. Don't remember the specifics about the chassis as they were replaced as a FRU. I would think throughput would depend on what flavour RAID was configured but reasonably fast for the time since it was fibre. I think they were primarily used for nearline storage.