Facebook: Managing data store locality at scale with Akkio

To the best of our knowledge, Akkio is the first dynamic locality management service for geo-distributed data store systems that migrates data at microshard granularity, offers strong consistency, and operates at Facebook scale.

...wow. This is like nothing I've ever read. It delves deep into Facebook's solution for how to map a file to a datacenter, and the results are impressive:

(Akkio has resulted in a) 50 percent reduction of the corresponding WAN traffic and an approximately 50 percent reduction in perceived latency.

Facebook has written a paper on Akkio and will be presenting it at OSDI 2018.