Are different OS versions supported in the same cluster?

[pshroads]

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?

Thanks!

[jasontedor]

Generally speaking, this should not cause you any issues. Of course you might run into some configuration issues, but as soon as Elasticsearch is up, it should be fine.

[xavierfacq]

Keep in mind that a shard created on a master 2.4.3 will not be able to be replicated on 1.7.5 node.

If I had to do that, I would:

• Install CentOS with the last version on your 10 news machines
• Install ES 2.4.3 on thoses new machines (7 data nodes, 3 master nodes)
• Add one by one your machines to your cluster (data nodes first)
• Stop old data notes
• Remove your old master node, a new master 2.4.3 will be elected

My 2 cents: test the manipulation on a test-platform