Chapter 10: Running ZooKeeper
- When an ensemble has enough ZooKeeper servers to start processing requests, we call the set of servers a quorum. Of course, we never want there to be two disjoint sets of servers that can process requests, or we would end up with split brain. We can avoid the split-brain problem by requiring that all quorums have at least a majority of servers. (Note: half of the servers do not constitute a majority; you must have greater than half the number of servers to have a majority.)