For a production setup, it is recommended to use a SolrCloud cluster or Solr leader/follower index replication. With Solr leader/follower index replication one Solr node - the leader - handles index updates, while one or more other Solr nodes - the followers - handle high query load. Solr followers periodically replicate index changes from the Solr leader. Such a setup allows the distribution of high query load across multiple Solr follower nodes and also provides basic fault tolerance for the query side. For replication without latency and better fault tolerance consider SolrCloud, which is described in Section 3.4, “SolrCloud”.

You can find more information about leader/follower index replication in Solr Reference Guide: User-Managed Index Replication.