On 10/28/2014 3:42 AM, Bernd Fehling wrote: > Thanks for the explanations. > > My idea about 4 zookeepers is a result of having the same software > (java, zookeeper, solr, ...) installed on all 4 servers. > But yes, I don't need to start a zookeeper on the 4th server. > > 3 other machines outside the cloud for ZK seams a bit oversized. > And you have another point of failure with the network between ZK and cloud. > If one of the cloud servers end up in smoke the ZK system should > still work with ZK and cloud on the same servers.
The only problem with 4 zookeepers instead of 3 is that with both situations, only one server can go down. With 3 servers, you have one less possible point of failure, so it's actually a little more stable. Might as well stick with three, or move to five where you can have two failures. > So the offline argument says the first thing I start is ZK and > the last I shutdown is ZK. Good point. > > While moving fom master-slave to cloud I'm aware of the fact that > all shards have to be connected to ZK. But how can I tell ZK that > on server_1 is leader shard_1 AND replica shard_4 ? As Markus already said, the leaders will be automatically chosen, there's very little you can do to influence the elections. This should be changing in version 5.0, though. See this umbrella issue and its dependent issues, which add the ability to choose which replicas are the preferred leaders, and force an election: https://issues.apache.org/jira/browse/SOLR-6491 Thanks, Shawn
