RESTBase/Table storage backend options

This page collects details on possible backends for the RESTBase table storage layer. Please add more candidates and information.

Exclusion criteria
These criteria need to be satisfied by candidates:
 * No single point of failure
 * horizontal read scaling: can add nodes at any time; can increase replication factor
 * horizontal write scaling: can add nodes at any time
 * Has been hardened by production use at scale