Yeah, it took me a few tries to get it all straight in my head. Perhaps this will help. Whether or not to install Zookeeper on the same node as Solr is entirely your decision. And I'm assuming that you're NOT talking about the embedded Zookeeper BTW.
The only "problem" with running ZK on the same node as Solr is that if the node goes down, it takes _both_ zookeeper and Solr with it. If running the "embedded zookeeper", then you can't even bounce the Solr server without taking down the ZK node. Solr will run fine even with embedded ZK, you just have to be very careful when you take the node up or down. Bottom line: It's just easier, from an administrative standpoint, to run Zookeeper as an external process. That way, you can freely bounce your Solr nodes without falling below quorum. Whether or not it shares the same machine as a running instance of Solr is up to you. As long as one replica for each Solr node is running _somewhere_, and as long as a ZK quorum is present, your Solr instance will run fine. You're completely correct that having all multiple replicas on the same box (with or without Zookeeper running there) is "less robust" than running them all on separate machines. But it may be "good enough". Especially when you have big hardware, you want to make use of all that hardware so running multiple Solrs (and maybe Zookeeper) can make sense. You absolutely _do_ want to 1> have at least one replica for each and every shard on a different box 2> have each Zookeeper running on a separate box. That way, if any single box dies you have a complete collection available and a quorum of ZK nodes present. How many more machines you have and how you distribute your collections amongst them is up to you. I will add, though, that machines shouldn't die very often, so it's easy to over-think the problem. Best, Erick On Tue, Apr 28, 2015 at 3:40 AM, shacky <shack...@gmail.com> wrote: > Hi. > > I'm using Solr for 3 years and now I want to move to a SolrCloud > configuration on 3 nodes which would make my infrastructure highly > available. > But I am very confused about it. > > I read that ZooKeeper should not be installed on the same Solr nodes, > but I also read another guide that installs one ZooKeeper instance and > 2 Solr instance, so I cannot understand how it can be completely > redundant. > I also read the SolrCloud quick start guide (which installs N nodes on > the same server), but I am still confused about what I need to do to > configure the production nodes. > > I installed all my 3 nodes and runned Solr 5.1.0 on all of them, now I > have to configure ZooKeeper on all nodes and run Solr in SolrCloud > configuration. > I want a completely redundant infrastructure, with both indexing, > replication and searching available and working with the tolerance of > one node. > > Could you help me to fresh my mind, please? > > Thank you very much! > Bye
