Please also note that there are two concepts here that can easily get mixed. For clarification:
* Zookeeper's wire protocol is emulated in CH-Keeper. Nice! So all clients are compatible, etc.
* Zookeeper uses a distributed consensus algorithm called ZAB. Which is not Paxos --but many believes so. CH-Keeper uses Raft, and it can do so as the consensus algorithm is not exposed directly: it is an internal property hidden behind the API and obviously the wire protocol.
It appears to be implemented with Raft, not Paxos (per https://presentations.clickhouse.com/meetup54/keeper.pdf, slide 21).