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Whether replicationFactor=2 makes sense in SolrCloud?

We are trying to building our solr cloud servers, we want to increase replicationFactor, but don't want to set it as 3 as we have a lot of data.

So I am wondering whether it makes sense to set replicationFactor as 2, and what's the impact, whether this will cause problem for replica leader election such as split brain etc?

Thanks

Solution

  • replicationFactor will not affect whether a split brain situation arises or not. The cluster details are stored in Zookeeper. As long as you have a working Zookeper ensemble Solr will not have this issue. This means you should make sure you have 2xF+1 zookeper nodes (minimum 3) . From zookeeper documentation:

    For the ZooKeeper service to be active, there must be a majority of non-failing machines that can communicate with each other.

    To create a deployment that can tolerate the failure of F machines, you should count on deploying 2xF+1 machines.

    Here are some links explaining it further:

    http://lucene.472066.n3.nabble.com/SolrCloud-and-split-brain-tp3989857p3989868.html

    http://lucene.472066.n3.nabble.com/Whether-replicationFactor-2-makes-sense-tp4300204p4300206.html