Flavio: I think you're missing a critical bit about SolrCloud, namely Zookeeper (ZK), see here on the SolrCloud page for a start: http://wiki.apache.org/solr/SolrCloud#ZooKeeper
You'll notice that each Solr node, when it is started, requires the address of your ZK ensemble, NOT a solr node. That allows ZK to "know" where all the nodes are in your cluster. So each of the nodes "just knows" where all the other shards are since that info is kept it ZK, so any request to any node in the cluster "does the right thing", whether update or query. So updates are forwarded to all correct leaders, queries are sent to a member of each shard etc, all automatically. Now take a look at CloudSolrServer (assuming that you're using SolrJ from your client). The constructor takes the address of ZK too. Using this info the client code has access to information about the state of the entire cluster, so you don't have to do anything, the client code will just "know" how to connect to Solr. So for 1, 2 and 3 above, don't do anything <G>. Just start up all the solr nodes with the proper zkHost (or zkRun) parameter and send requests to any node. You do NOT have to configure shards in solrconfig.xml or anything else. For <4>, I'm going to pass on the shard splitting details since I haven't had time to dive into that yet. But increasing capacity comes in two "flavors". If you simply need to get more query throughput, just add more nodes. Solr will assign them to "the right" shard (although you can control this), copy the index for that shard down and start automatically routing new requests to that node too. The second "flavor" is when your index is too big to fit on your physical hardware and you need more shards (as opposed to more replicas). Then you need to do the shard splitting thing which I'm going to skip rather than mislead you. Final note: The other thing that's confusing you I think is the distinction between SolrCloud and Solr Master/Slave. SolrCloud is the new way of doing things. Master/Slave is a situation in where all the automatic stuff you can do with SolrCloud must be done manually, things like assigning documents to particular shards, configuring solrconfig.xml with the addresses of all the other shards, all that stuff. Best Erick
