Zookeeper in the only clustering product I’ve ever used that actively refused to start a cluster after an all-nodes stop/start.

It blows my mind that a high availability system would purposefully prevent availability as a “feature”.

Although this is oversimplifying things [0], in the face of partitions zookeeper emphasizes consistency over availability.

[0] https://martin.kleppmann.com/2015/05/11/please-stop-calling-...