On 5/14/2021 3:12 PM, jerome moliere wrote:
I would like to know the best practices to migrate a mission critical Solr cluster from version 6.x to 8.x without any service shutdown. Is the double upgrade required (mandatory) ? We can introduce another temporary group of machines ro join the cluster, then we may stop the existing nodes one by one once upgrade done... In this case we have different indexes and 2 replicas per shard...
If you have an index that has ever been touched by a 6.x version, you can't use it in 8.x, even if you first upgrade it with a 7.x version. It will fail. Reindexing is required. Jumping more than one major version was iffy and not recommended before 6.x, now it is explicitly enforced as not possible. The enforcement is done by Lucene.
Is it possible to have concurently 2 versions of SolR running in the same cluster?
It would not be recommended at all to run two different major versions in one cluster. I am assuming SolrCloud here, where the nodes are always talking to each other.
Of course a full reindexing seems to be required , there is no problem we have enough time ( upgrade procedure is not required to be finished in a short time). I would like to have a summary of options available , pros & cons for each one and if possible a few tips & tricks to avoid some pitfalls...
Build the new cluster separately from the old one. They could share the same zookeeper ensemble by setting up the new cluster with a different chroot.
Create new config files for the indexes with the new version examples as starting points.
Build the indexes from scratch on the new cluster. Switch the URLs in your application to point to the new cluster. Thanks, Shawn
