ambry is a distributed object store that supports storage of trillion of small immutable objects (50K -100K) as well as billions of large objects. It was specifically designed to store and serve media objects in web companies. However, it can be used as a general purpose storage system to store DB backups, search indexes or business reports.
A 2014 paper describes the design of ambry. The 2016 announcement published when the code was released as Free Software also contains a detailed description of the architecture.
Blog entries related to storage & ambry on the Linkedin engineering web site.