We have an 8 node cluster with all nodes running CentOS 6.5 and elasticsearch 1.7.5. We have purchased 10 new machines and want migrate off the 8 old nodes by adding the 10 new machines to the cluster and then removing the original 8.
However we also are planning on upgrading to elasticsearch 2.4.2 in the near future and would like to get the OS up to CentOS 7.1 as well. Since upgrading the OS is much more disruptive I was thinking of installing CentoOS 7.1 on the new machines before I add them to the cluster as long as there will not be any issues with having a cluster with CentOS 6.5 and 7.1 hosts (albeit only temporarily while we migrate off the old machines). Any thoughts and/or alternate approaches?