"Geo-replication brings two key benefits to Web services: fault tolerance and low latency. It provides fault tolerance through redundancy: if one data center fails, others can continue to provide the service. It provides low latency through proximity: clients can be directed to and served by a nearby data center to avoid speed-of-light delays associated with cross-country or round-the-globe communication.
Geo-replication brings its challenges, however. The famous CAP theorem, conjectured by Brewer1 and proved by Gilbert and Lynch,7 shows it is impossible to create a system that has strong consistency, is always available for reads and writes, and is able to continue operating during network partitions."
This experiment shows that for this real-world workload Eiger's causal consistency and stronger semantics do not impose significant overhead.
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