SolrCloud's choice of a leader isn't "sticky"; it can change and won't necessarily change back on its own if the original choice is eligible again. Setting "preferredLeader" on a replica and calling the REBALANCELEADERS API is how to make it sticky.[1]. Without this, a rolling restart (common-place in a cloud-native world?) will leave the last node without any leaders. That can lead to a resource usage imbalance, particularly with TLOG due to the higher differentiation of activity a leader does vs a non-leader. Make sense?
Would it make sense for collection creation to have a setPreferredLeader option or some-such boolean name? Or just let the caller/client do so if it pleases, and maybe mention this as advice in the reference guide? Or just do this by default for TLOG collection creation... although I wonder if it'd interfere with how some users manage their clusters? [1] https://solr.apache.org/guide/solr/latest/deployment-guide/collection-management.html#rebalanceleaders ~ David Smiley Apache Lucene/Solr Search Developer http://www.linkedin.com/in/davidwsmiley
