Currently working with a 4 node ELK cluster (7.6) with 10k indices, 20k Primary Shard, 12k replica shards.
To stabilise the cluster performance, I have attempted freezing and closing indices. so the number of open non-frozen indices is 160 primary + 160 replicas.
A rolling restart is currently taking 5+ hours per node and overall performance is very slow to search.
Is it expected that frozen indices do have impact on cluster performance, even if it is closed and frozen?