Hi - FoundationDB founder here. I'll point you to a comment thread from a previous HN discussion where my co-founder Dave Scherer addressed how we deal with partitions:

http://news.ycombinator.com/item?id=4295770

Please let us know if you have any questions this doesn't answer and we'd be happy to answer. Also, if you'd like to actually SEE us deal with a data partition, we can show you that live at Disrupt with the demo cluster we've built :)