If you need to rename your elasticsearch cluster or you want to merge two separate elasticsearch clusters we have used the following technique to retire an elasticsearch node "into" a new elasticsearch cluster.

1. Join old node(s) to new cluster by changing their cluster name to the new cluster’s name. Verify that they joined.
2. To migrate shards off of the old nodes you have to issue curl's to the old node, e.g.

http://stackoverflow.com/questions/17268495/how-to-remove-node-from-elasticsearch-cluster-on-runtime-without-down-time

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