Zone awareness-alike behaviour for single index


It would be cool if something like zone awareness behaviour would be easily achieved on per-index level.

Example use case here is: some older/cold indexes, that I'd like to offload to storage nodes, but still keep replica of data on faster nodes too. Unfortunately include/require/exclude allocation filters aren't really capable to achieve that (as I can only move index with all its shards).

Or maybe I'm missing something and this is possible?

It's not possible. And it doesn't make a lot of sense.

Actions against an index set (primary + replica/s) is done synchronously. So If you had the replicas on slow hardware it'd impact overall performance.