Migrating from ES 2.4 to 6.2, best approach?

[ahbruinsma (Andries Bruinsma)]

Hello,
I'm fairly new to EleasticSearch, but we've got 2 clusters already. A 2.4 cluster running on 2 nodes and a 6.2 cluster running on 4 nodes. Now we want to migrate the data on the 2.4 cluster to the 6.2 cluster, but what would be the best approach?

1. Is it possible to upgrade the 2.4 to 6.2 (using the https://www.elastic.co/guide/en/cloud-enterprise/current/ece-upgrading-v6.html topic) and just add the nodes of the first cluster to the second cluster and than later on remove the first two again?

2. Try an migrate the data using the Reindex API?

3. Something else?

With kind regards,
Andries Bruinsma

[warkolm (Mark Walkom)]

1 - ECE does a lot in the backend for you, things you'd need to do manually otherwise.
2 - Ideally, yes. This will let you update data structures and refresh mappings etc

[luxiaoxun]

We are going to do the same thing. Are you guys going to use "Java rest client" to replace "Java TransportClient"? since "Java TransportClient" will be removed from ES 7 and ES 8.