In our production environment, we have Master-Slave SOLR server configuration. We have 2 SOLR slave servers and configured SOLR load balancing URLs in prod CM and CD servers. Right now we are facing intermittent issues with our custom indexes and our search is not working properly. So every time we face this intermittent issue we need to rebuild the custom indexes to get the search results.
After investigation, we found that custom indexes in one of the SOLR slave servers are getting out of sync sometimes with the master SOLR server.
Our custom indexes have primary and secondary cores which also point differently in master and slave servers as we are using SwitchOnRebuildSolrSearchIndex.
Production Environment: For production, we have one Sitecore content management server and two content delivery servers.
Solr version: 7.2.1
Sitecore version: 9.1.0
enable.master = true
enable.slave = false
enable. master = false
enable. slave = true