Hi Is it possible for a replica to be DOWN, while the node it resides on is under /live_nodes? If so, what can lead to it, aside from someone unloading a core.
I don't know if each SolrCore reports status to ZK independently, or it's done by the Solr process as a whole. Also, is it possible for a replica to report ACTIVE, while the node it lives on is no longer under /live_nodes? Are there any ZK timings that can cause that? Shai