Zookeeper hard
If the Leader and all Followers crash, leaving only 3 Observers alive, can the cluster function?
- A Yes, Observers can elect a leader.
- B Yes, in read-only mode.
- C No. Observers do not participate in Quorums. With 0 voting members, the cluster is effectively dead and cannot elect a new Leader or serve requests.
- D Yes, if configured as 'promotable'.
Answer: C. No. Observers do not participate in Quorums. With 0 voting members, the cluster is effectively dead and cannot elect a new Leader or serve requests.
Observers are passive learners. They have no voting rights. A cluster needs a majority of *Participants* (Voters) to function.
One system design question a day, with spaced repetition so the ones you miss come back.
Get the appRelated questions
- What is the primary technical function of a ZooKeeper 'Watch'?
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- By default, `forceSync` is enabled. If you disable it, what trade-off are you making?
- If the specific ZooKeeper node a client is connected to crashes, what should the client do?
- Which cluster configuration has *worse* availability: A 3-node cluster or a 4-node cluster? (Assuming simple majority quorum)
- According to the CAP Theorem, how is ZooKeeper classified?