Context:
My company is using Solr 7.0 in cloud mode, kept in sync by a Zookeeper ensemble; 3 Solr nodes, 3 Zookeeper nodes; 1 collection, 1 shard, 3 replicas (each replica on one of the Solr instances): collection1_shard1_replica_n1 (on Solr1); collection1_shard1_replica_n2 (on Solr2) and collection1_shard1_replica_n3 (on Solr3); all kept in AWS. This Solr setup was created many years ago.