On Sep 20, 2011, at 8:37 AM, Buttler, David wrote: > Wait, you do realize that you have to have a majority of zookeeper nodes > alive for zookeeper to work, right? That means that you get lower > reliability with two nodes than one node: if either node goes down, zookeeper > will give up. This also implies that you need to have an odd number of nodes > in your zookeeper ensemble.
I keep seeing this last part repeated and I believe it is a misunderstanding. There is no requirement for an odd number of nodes, although adding a node to an odd-numbered set will not increase reliability. “For this reason, ZooKeeper deployments are usually made up of an odd number of machines.” <http://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_CrossMachineRequirements> joe
