Has anyone considered Joyent's Manta ?
This is a distributed object storage with integrated compute.
Data is stored on a cluster of SmartOS hosts..
And processed directly on each host inside a OS container (SmartOS zone), no data movement.
Lot of APIs available: R, command-line, python, ruby, node.js etc..
Available on their cloud and as a on-premises commercial product, opensourced last November (simulteanously with smartdatacenter).