I have a cluster with two 6.0 Nuxeo Nodes and a single ES node. I will upgrade to LTS 2015 with three 6.0 Nuxeo Nodes and three ES nodes (seems two ES nodes is not recommended because of split brain issue). The operation is quite heavy an I d like it to be as short as possible, of course.

First, I m asking myself what is the easiest way to setup that environnement : add the ES nodes (before / during / after) the (upgrade / setup) of new servers ?

Is the ES configuration (shards and replicas) done only on clients (each Nuxeo node having the same configuration) ?