Chaos: the paper that pushed the limits
Chaos is a graph processing system for analytics on big graphs using small clusters. Chaos builds on the X-Stream single-machine graph processing system, but scales out to multiple machines. Chaos treats the aggregate storage of all machines as a single flat disk and uses work stealing to balance the load across nodes in the cluster. It exposes the familiar scatter-gather-apply programming model.
For more details, you can find the paper here.