I am trying to migrate my existing active elasticsearch cluster to newer one using snapshot/restore. But facing some problem. On restoring the indices for the first time, it is okay. When I try to restore new snapshot the second time, it says either to delete existing indices or to close them. But, if I'll close any existing indices, how will I be able to make these 2 clusters in sync with each other? Because restoring takes time and so do snapshot.
Also, I have some doubts:
- Why do we need to close these existing indices even if we are not appending any new entries to the indices?
- What is the best approach to migrate elasticsearch cluster? [In both the clusters I'm using same version of Elasticsearch (6.4.0)]