The classic problem of ZooKeeper is the client and the server upon initial startup will DNS resolve and permanently cache the IP addresses of the ZK cluster.  Thus any cluster migrations require you to restart _EVERYTHING_.<p>So running zookeeper in a dynamic environment becomes very risky.  Aka AWS.  Perhaps on GCE it&#x27;s less dangerous, because the host migration is pretty good.<p>There are other operational issues people have noted above as well.