I ran into a seemingly well written article today on setting up a Galera cluster with master-master replication on Ubuntu. The questions that appear unanswered to me
a. Suppose I setup a cluster with 5 servers scattered across the four corners of the globe. Will the efforts at keeping them in synch result in a significant latency issue that will be to the detriment of the system as a whole?
b. Am I write in thinking that provided I get Galera up and running properly I can pretty much leave my PHP PDO code unchanged in the blissful assumption that Galera is handling replication so well that I have a cast iron guarantee of being able to access the same data on each server?