Hi, I have a SolrCloud setup, running 4.10.3. The setup consists of several cores, each with a single shard and initially each shard has a single replica (so, basically, one machine). I am using core discovery, and my deployment tools create an empty core on newly provisioned machines.
The scenario that I am testing is, Machine 1 is running and writes are occurring from my application to Solr. At some point, I stop Machine 1, and reconfigure my application to add Machine 2. Both machines are then started. What I would expect to happen at this point, is Machine 2 cannot become leader because it is behind compared to Machine 1. Machine 2 would then restore from Machine 1. However, looking at the logs. I am seeing Machine 2 become elected leader and fail the PeerRestore 2015-05-24 17:20:25.983 -0700 (,,,) coreZkRegister-1-thread-4 : INFO org.apache.solr.cloud.ShardLeaderElectionContext - Enough replicas found to continue. 2015-05-24 17:20:25.983 -0700 (,,,) coreZkRegister-1-thread-4 : INFO org.apache.solr.cloud.ShardLeaderElectionContext - I may be the new leader - try and sync 2015-05-24 17:20:25.997 -0700 (,,,) coreZkRegister-1-thread-4 : INFO org.apache.solr.update.PeerSync - PeerSync: core=project url=http://10.32.132.64:11000/solr START replicas=[http://jchar-1:11000/solr/project/] nUpdates=100 2015-05-24 17:20:25.999 -0700 (,,,) coreZkRegister-1-thread-4 : INFO org.apache.solr.update.PeerSync - PeerSync: core=project url=http://10.32.132.64:11000/solr DONE. We have no versions. sync failed. 2015-05-24 17:20:25.999 -0700 (,,,) coreZkRegister-1-thread-4 : INFO org.apache.solr.cloud.ShardLeaderElectionContext - We failed sync, but we have no versions - we can't sync in that case - we were active before, so become leader anyway 2015-05-24 17:20:25.999 -0700 (,,,) coreZkRegister-1-thread-4 : INFO org.apache.solr.cloud.ShardLeaderElectionContext - I am the new leader: http://10.32.132.64:11000/solr/project/ shard1 What is the expected behavior here? What’s the best practice for adding a new replica? Should I have the SolrCloud running and do it via the Collections API or can I continue to use core discovery? Thanks.
