Zookeeper Experts.
The question that I am asking might be basic to you, but I am new to ZK, and I haven't mastered the tool yet so forgive me. With that in mind here is my question.
Suppose I have a ZK Cluster of 5 Servers, and I have a quorum of 3. Now this guarantees that the servers won't go into split-brain scenarios, if they are located into two physically separate DC or machines right.
However, what I want to know is if the Quorum is set to three it means that the Leader server, will need to wait until at least 2 server replicate the written data, total of 3 replicated data. But what if a client connects to the server that is not part of the Quorum any of the 2 servers, isn't that means it gets the old data ?
First, you cannot "set" the quorum. It is automatically calculated from the configuration, using
N/2+1(the majority) where N is the number of zookeeper server *.A Zookeeper server that is not part of a Quorum become unavailable and cannot server data to clients so no risk of seeing old data.